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THESIS

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This is to certify that the

thesis entitled

THE VEGETATION HISTORY AND PALEOCLIMATOLOGY
FOR THE LATE QUATERNARY 0F
ISLA DE LOS ESTADOS, ARGENTINA

presented by

Warren Harvey Johns

has been accepted towards fulfillment
of the requirements for

Master of Science degree in Geology

Major professor

Date "i/Ma /31 / 7487/ Aurea] T. Cross

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© Copyright by
WARREN HARVEY JOHNS
1981

THE VEGETATION HISTORY AND PALEOCLIMATOLOGY
FOR THE LATE QUATERNARY OF
ISLA DE LOS ESTADOS, ARGENTINA

By

Warren Harvey Johns

A THESIS

Submitted to
Michigan State University
in partial fulfillment of the requirements
for the degree of

MASTER OF SCIENCE

Department of Geology

1981

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ABSTRACT
THE VEGETATION HISTORY AND PALEOCLIMATOLOGY

FOR THE LATE QUATERNARY OF
ISLA DE LOS ESTADOS, ARGENTINA

By
Warren Harvey Johns
Pollen has been analyzed from three cores retrieved from the
peat of Isla de los Estados, just east of Isla Grande, Tierra del Fuego.
The three resulting pollen diagrams indicate paleoecological and paleo-
climatological trends over the past several thousand years in the
southeastern-most extension of the Magellanic rain forest. Arboreal

pollen is almost exclusively from the southern beech (Nothofagus). A

 

computer program was devised in attempting to differentiate mathe-

matically the two main components of the island's Nothofaggs flora,

 

N, betuloides from N, antarctica, based upon the relative number of

 

 

apertures of the pollen grains. Four full major vegetational cycles
are detected from the pollen spectrum of the 9.6-m Bahia Crossley core,
and these may indicate the effects of long-term paleoclimatological

and paleoecological trends upon the local flora.

ACKNOWLEDGMENTS

A debt of gratitude is owed to many individuals who have made
this thesis possible. First of all, my heartfelt appreciation goes
to the chairman of my thesis guidance committee, Dr. Aureal T. Cross,
who took a special interest in me upon my first arrival at Michigan
State University in 1975 and who has provided expert guidance and keen
insights all along the way. My sincere thanks go to Dr. Ralph Taggart
and Dr. C. E. Prouty, who have also provided much-needed assistance
as members of my thesis guidance committee. A special note of apprecia-
tion goes to the Department of Botany for providing samples from Isla
de los Estados and to Dr. Taggart for his help particularly in solving

the difficult Nothofagus taxonomy. Valuable discussions with Dr. Harry

 

Imshaug, Department of Botany and Plant Pathology, Michigan State
University, and Dr. David Moore, Department of Botany, University of
Reading, are also gratefully acknowledged. And finally, a debt of both
gratitude and love goes out to my wife, who cheerfully did the pains-
taking job of typing the thesis and provided undying support and

encouragement from start to finish.

1'1

TABLE OF CONTENTS

 

Page
ACKNOWLEDGEMENTS ........................ ii
LIST OF TABLES ......................... v
LIST OF FIGURES ........................ vi
LIST OF PLATES ......................... vii
INTRODUCTION .......................... 1
Chapter
I. SUMMARY OF PREVIOUS STUDIES ON ISLA DE LDS ESTADOS . . . 3
Botanical Studies .................. 3
Geological Studies ................. 5
Meteorology ..................... lO
Palynology, Paleoecology. Paleoclimatology ..... 14
II. METHODS AND TECHNIQUES ................. 16
Collection of the Samples .............. 16
Preparation and Mounting Techniques ......... l8
Identification of the Palynomorphs ......... l9
Counting Techniques ................. 2l
Photographic Techniques ............... 22
III. RESULTS ........................ 23
Core II ....................... 23
Core III ...................... 28
Core VI ....................... 29
Comparisons between the Three Cores ......... 33
IV. DISCUSSION ....................... 36
Towards a Paleoecological Interpretation ...... 36
Interpretative Problems and Possible Solutions . . . 43
A Possible Solution to Identification of
Nothofagus Pollen ................ 52
Paleoecological Interpretation for Core II
(Puerto Cook-Puerto Vancouver) .......... 61
Paleoecological Interpretation for Core III
(Puerto Celular) ................. 68

iii

Paleoecological Interpretation for Core VI

(Bahia Crossley) ................. 71

Synthesis ...................... 78

LIST OF REFERENCES ....................... 86
Appendix

A PROCESSING AND MOUNTING TECHNIQUES .......... 91

B COMPUTER PROGRAM FOR DIFFERENTIATING NOTHOFAGUS SPECIES 93

 

 

 

 

C NOTHOFAGUS APERTURE COUNT--CORE II .......... 94
D NOTHOFAGUS APERTURE COUNT--CORE III .......... 96
E NOTHOFAGUS APERTURE COUNT--CORE VI ........... 97
PLATES ............................. 100

iv

Table

LIST OF TABLES

Geological Sequence for Tierra del Fuego ......

Temperature and Precipitation Data for S. Chile,
S. Argentina, and Argentine Islands .......

Climatic Data for Isla de Los Estados and Two
Nearby Stations .................

Pollen Zonation for Core VI, Bahia Crossley

Vegetation Formations of Isla de los Estados . . . .

Page

11

12
31
44

LIST OF FIGURES

Figure Page
1. Map of Isla de los Estados .............. 17

2. Pollen Diagram from the Peat Deposits of the
Puerto Vancouver-Puerto Cook Isthmus, Isla
de los Estados, Argentina ............. 24

3. Pollen Diagram from the Peat Deposits near
Puerto Celular, Isla de los Estados,
Argentina ..................... 25

4. Pollen Diagram from the Peat Deposits East
of Bahia Crossley, Isla de los Estados,
Argentina ..................... 26

5. Comparison of the Percentages of 7-Aperturate
Nothofagus with the Relative Frequencies of
Total Nothofagus .................. 60

 

6. Four Major Vegetational Cycles in Core VI ....... 73
7. Comparison of the Late Quaternary Paleotemperature

Trends in the High Latitudes of the Southern
Hemisphere .................... 81

vi

LIST OF PLATES

Plate Page
1. Figures 1-1 through 1-17 ................. 100
2. Figures 2-1 through 2-25 ................. 102
3. Figures 3-1 through 3-29 ................. 104
4. Figures 4-1 through 4-16 ................. 105
5. Figures 5-1 through 5-34 ................. 103
6. Figures 6-1 through 6-16 ................. 110

vii

INTRODUCTION

Isla de los Estados (Staten Island), Argentina, is located just
off the eastern tip of Tierra del Fuego at approximately 5505, 640W.
Oriented along an east-west axis, it is just over 60 km long, a maximum
of 18 km wide, and has a maximum elevation of nearly 1000 m. It is
separated from Isla Grande of Tierra del Fuego by the 30-km wide
Estrecho de le Maire to the west. The much wider Drake Passage separates
it from the Antarctic Peninsula and South Shetland Islands to the south.
The island has a very irregular coastline with numerous fjord-like bays,
some of which almost bisect the island.

Botanically, the island is located at the easternmost edge of
the Magellanic evergreen rain forest, which is the southernmost forest
in the world. This forest extends as far south as Islas Hermite at
5605, which is only about 800 km from the Antarctic Peninsula. Isla
de los Estados itself has dense, impenetrable thickets of the southern
beech, Nothofagus, thus making exploration of the island on foot very
difficult. Expeditions to the island have discovered that the best
method of collecting is landing at the many sheltered bays and
making short forays into the surrounding land area.

One such expedition, R/V Hg§g_Cruise 71-5, was designed to study
primarily the terrestrial plant life of the island, although ostracodes
and various microfauna were studied through bottom-sampling in the bays.

During that expedition, October 11 to November 14, 1971, three cores of

peat deposits were obtained and returned to Michigan State University
for pollen analysis. The cores were from the mid-eastern, central, and
far western portions of the island and can serve as a basis for the
reconstruction of the vegetation history of the island since the end

of the last glaciation.

The purpose of the present study is to report the results of
the pollen-analytical work on these three cores and to interpret the
variations in the pollen spectra in terms of paleoecological, vegeta-
tional, and paleoclimatological changes. Present-day analogs in the
form of plant communities now inhabiting the island will be used to
develOp a reconstruction of the plant successional changes during the
Postglacial period. The reconstruction will then be compared with

other reconstructions for Tierra del Fuego and southern Patagonia.

CHAPTER I
SUMMARY OF PREVIOUS STUDIES
ON ISLA DE LOS ESTADOS

Botanical Studies

The Tierra del Fuego area, of which Isla de los Estados is a
part, was visited by the first plant collector, George Handisyd, in
l690. Since then more than 200 collectors have visited the area, and
of these, 80 have published reports (Moore, l974, I975). The first to
discover Isla de los Estados were Schouten and Le Maire, who named it
Staten Island (Isla de los Estados) in 1616 after their homeland which
was Holland (Imshaug, 1972). The first naturalists to visit the island
landed in 1774 while Captain Cook's ship anchored off Islas Ano Nuevo
on his second voyage (Imshaug, 1972). However, their collections were
limited to that small group of islands which are off the north coast of
Isla de los Estados.

Other collectors to Isla de los Estados followed in succession:
Menzies in 1787, Foster in 1828, Hahn in 1882, and Racovitza in 1898
(Imshaug, 1972). Two collectors in the late 19th century had their
reports published in national museum publications: Alboff at LaPlata,
in 1896, 1897, and Spegazzini at Buenos Aires, in 1896 (Moore, 1974,
1975). The Swedish South-Polar Expedition first visited the island in

1902, and again in 1903 following the wreck of the ship Antarctica,

 

and out of these expeditions emerged the classic studies on the botany

of the island. As a result, a number of extensive monographs were

published first by C. J. F. Skottsberg, in 1906, 1913, 1916, and 1926,
and then by H. Roivainen, in 1954, most of which were in German (Moore,
1974, 1975). While minor expeditions to the island were conducted by
botanists, Hicken, in 1912 and Castellanos, in 1933-1934 (Imshaug, 1972),
the only major botanical expeditions comparable to that of the Swedish
Expeditions early in the century were the R/V ngg_cruises conducted
within the last decade.

The R/V ngg_Cruise 71-2 consisted of a survey of the vertebrates.
arthropods, and marine biota at Isla de los Estados, and this was
complemented by R/V 5339 Cruise 71-5 whose primary goal was to survey
the terrestrial plant life (Imshaug, 1972). This latter cruise in
October and November, 1971, resulted in the retrieval of the three peat
cores which served as the basis for this study.

Numerous botanical studies have been spawned by the expedition,
most of which are still in progress. The lichens are being studied
mainly by Dr. H. A. Imshaug (Michigan State University), the bryophytes
by several individuals, and the vascular plants by Dr. T. R. Dudley
(U.S. National Arboretum) and Dr. Garrett E. Crow (University of
New Hampshire). A flora for the vascular plants is being published by
Dudley and Crow (in press). Apart from the R/V ngg_studies, a more
comprehensive flora is being developed and analyzed for the entire south
Patagonian and Fuegian area under the direction of Dr. David Moore
(University of Reading, U.K.), while a flora representing Tierra del
Fuego has already been published (Moore, 1974).

As far as I am aware, no palynological studies have been done
for Late Quaternary deposits on Isla de los Estados until the time of

the R/V Hero Cruise 71-5. Dr. Ralph Taggart (Michigan State University)

has undertaken the study of the Postglacial history based on palyno-
logical analysis of the peat cores collected by that expedition. This
study serves to complement Auer's series of pollen profiles developed

from bog studies for central and eastern Tierra del Fuego (Auer, 1965).

Geolggical Studies

 

The geological surveys have not been nearly so numerous and
extensive as the botanical surveys on Isla de los Estados. Windhausen's
survey of the geology of Argentina does not refer to Isla de los Estados
in the text, although his geological map (Windhausen, 1931) does depict
the island as being bisected into two main lithological types:

I) a marine sedimentary sequence from Jurassic

to Cretaceous (Neocomian);

2) a porphyritic sequence of Triassic age.

The earlier geological reports were sketchy and at best fragmentary, so
it was not until 1943 that the first synthesis of the early reports was
published by Harrington (in Spanish), together with the results of his
own summer field work there in cooperation with the Argentine Navy
(Harrington, 1943, cited in Dalziel, gt 21., 1974). Some of Harrington's
work has appeared more recently in English (Harrington, 1956, 1962).

An even more comprehensive survey of the island was conducted
by R/V Hg§9_Cruise 72-2, which was a joint Argentine-United States
geological venture sponsored by the U. S. Antarctic Research Program.
The expedition, which took place during April and May, 1972, had the
services of geologists I. W. D. Dalziel and K. F. Palmer, of the Lamont-

Doherty Geological Observatory, and Argentine geologists R. Caminos,

F. Nullo, and R. Casanova, of the University of Buenos Aires. Like the
botanists on a previous expedition, they found it nearly impossible to
study the island extensively on foot due to the almost impenetrable
tussock grass and extremely dense thickets of southern beech in the
lower elevations. Landings could not be made at most points along the
rocky coast, but only at the more sheltered bays and fjords. In a
matter of six weeks more than 200 landings were made around the full
perimeter of the island, and several hundred rock and mineral samples
collected. The following geological studies have been published incor-
porating the data derived from the R/V ngg_Cruise: a brief preliminary
report of the expedition (Dalziel, 1972), a comprehensive report of the
conclusions reached (Dalziel, gt_al,, 1974), and other reports dealing
with the whole regional geology of the southern Andes (Dalziel, 1976;
Dalziel, gt_al,, 1975, 1977).

Most of the island is composed of silicic volcanic rocks, such
as tuffs, ignimbrites, and lavas that were deposited in a shallow
marine environment with scattered volcanic islands. Overlying the
volcanic sequence is a homogeneous sequence of black mudstones and
shales that crop out along a narrow portion of the northernmost parts of
the island and a wider area at the western end of the island, as well as
on the four islands to the north of the main island. The contact between
the volcanic and sedimentary sequences is conformable. The recent
geological studies on the island have resulted in the following revisions
of Harrington's analysis (Harrington, 1962):

l) Within the upper portion of the volcanics are often found
thin units of pure black mudstones, which lithologically are indis-

tinguishable from the mudstones of the overlying sedimentary sequence.

Harrington believed that these mudstones were all fault-bounded
outliers of the overlying sequence. The most recent studies have shown
that these mudstones were deposited at the same time as the volcanics
and are to be considered as intercalations in the transitional contact
between the volcanics and overlying mudstones and shales. There is no
evidence for faulting at the contact, which is shown to be conformable.
2) Structurally, the island is an asymmetric syncline whose
axis extends roughly east and west. Harrington considered one of the
limbs of the fold to be overturned because sedimentary rocks underlie
volcanic rocks at Puerto Roca on the north-central coast. Later
geologists have interpreted these sedimentary rocks to be merely inter-
calations in the uppermost portion of the volcanics. However, recent
studies do indicate that locally one limb of the syncline was overturned,
but that appears to be only at the easternmost portion of the island.
Harrington assigned the sedimentary sequence to the Upper
Jurassic on the basis of the belemnites which he assigned to the genus
Belemnopsis. More recent studies have verified his interpretation. The
entire volcanic and sedimentary sequences on the island are thought to
be Upper Jurassic and Lower Cretaceous deposits, which correlates well
with an identical sequence for the subsurface of Isla Grande of Tierra
del Fuego, which has been deciphered by drilling, and with surface
mapping. The macrofossils collected by the R/V ngg_Cruise include,

in addition to the abundant belemnites, some pelecypods (Inoceramus),

 

some bryozoan-like fossils, and a single brachiopod; the microfossils
include radiolarians and foraminifers, which, to my knowledge, have

not been identified and reported as yet.

The formations described to date in Tierra del Fuego are
listed in Table 1 along with their lithological and faunal characteristics
and accompanying orogenic activity. The lowest identifiable formation
of the Cordillera which extends to Isla de los Estados is the Yahan
Formation (Jurassic). The Cretaceous formations, "Capas del Hito XIX"

and Leticia, both have the pelecypod Inoceramus, which was reported also

 

from Isla de los Estados, while the latter formation is characterized
by an abundance of mollusks (Borrello, 1972). The latest orogenic
activity would be the final uplift of the Andes in the late Pliocene,
thus forming the Cordillera along the southwest edge of Tierra del Fuego
which continues as the backbone of Isla de los Estados and offers the
explanation for the mountainous aspect of the island (Dalziel, gt_gl,,
1974).

The latest series of geological studies on the island, by
Dalziel and others, have largely concentrated on the structural relation-
ships between Isla de los Estados and the Andean Cordillera to the north
and the North Scotia Arc which extends to South Georgia Island. The
author is not aware of studies dealing with the geomorphology or the
glacial history of the island. Thus, there are many gaps in our knowledge
of its geological history, especially in regards to the entire Tertiary

and Quaternary epochs.

TABLE 1
GEOLOGICAL SEQUENCE FOR TIERRA DEL FUEGOa

 

 

 

 

 

 

 

 

 

 

 

Age Grogp Formation and Orogeny, Lithology Paleontology
movimiento valaquicos
Q)
C . . .
g, "Magallanense" conglomerate, beds of lignitic
0 coal
5: é’
E T movimiento pirenaicos
:
m w 0 O O O
*- 3’ R10 Bueno Formation foraminifera
(D
75
a O O O
mov1miento laramicos
Q 0 O o 0
g Let1c1a Formation Comanchian
g 35 mollusks
8 o
g ; Policarpo Formation sandstone mollusks
ti 8
S.
Q 0 ll ' II ' '
;§ Capas del Hito XIX limestone Albian mollusks
movimiento austricos
(oreggnianosT
Beauvoir Formation orthoflysch ammonites
.2
3 movimiento diablianos
E
3
'3

Lemaire Formation

Yahan Formation eugeosynclinal,
ophiolites

 

 

aData taken from Borrello (1972)

Meteorology

 

Meteorologically, Tierra del Fuego is known as one of the
stormiest inhabitable portions of the world, being subjected to incessant
winds. The dominant climatic factor that characterizes this region is
the strong wind, which nearly always blows from a westerly direction
and which almost never ceases, either summer or winter (Miller, 1976;
Prohaska, 1976). The wind is much stronger along the coast, having a
mean annual velocity of 12 m/sec at the westernmost Islas Evangelistas
contrasted with a mean of 4 m/sec inland at Punta Arenas (Miller, 1976).
Throughout southern Patagonia the wind often peaks in gusts 3O m/sec
(Miller, 1976).

Another climatic characteristic of this region is the lack of
seasonality as evidenced by a relatively small difference between
January and July temperatures (see Table 2). Thunderstorms and hail
are rare occurrences, while below freezing temperatures can occur any
month of the year, according to the data from Ushaia due west of Isla
de los Estados (Prohaska, 1976). There is no part of Tierra del Fuego
with greater than 100 frost-free days out of 365 days.

A synthesis of climatic data has been collected from several
sources and tabulated for twelve sites between 52° and 54° S latitude,
one of which includes a station at the eastern tip of Isla de los
Estados (Table 2). It should be noted that southward along the
Argentine coast, there is a decreasing temperature difference between

the January and July means (Rio Gallegos, Rio Grande, Ushaia, Isla

10

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14

de los Estados). This is an indicator of the lack of seasonality, as
already noted. Also, the amount of precipitation increases to the
south or southwest. Isla de los Estados lies in a band of high pre-
cipitation that extends northwestward along the pre-cordillerans through
the Grupo Evangelistas Islands, which have even higher amounts of
precipitation. Generally this band has greater than 2000 mm precipi-
tation annually, and in one case (Isla Guarello, 50°23'S, 75°20'W)
precipitation reaches a phenomenal 7500 mm annually; i.e., about
20 mm daily (Young, 1972).

The more detailed meteorological data for Isla de los Estados
itself is given in Table 3, accompanied by data from Observatorio
Island immediately to the north and from Ushuaia to the west on Isla

Grande.

Palynology, Paleoecology, Paleoclimatology

No published reports of the palynology of Isla de los Estados
have appeared in readily accessible journals dealing with the Mesozoic,
Tertiary, or Quaternary. Micropaleontological studies on the Mesozoic
samples collected by R/V 5359 Cruise 72-2 have concentrated on the
foraminifera and radiolarians, not on the pollen and spores.

From nearby Isla Grande of Tierra del Fuego, several Late
Quaternary palynological studies have been generated (Auer, 1958,
1960, 1966; D'Antoni, 1980; Markgraf, 1977; Markgraf and D'Antoni,
1977), while an occasional palynological study of recent material
from Tierra del Fuego has appeared in the literature, as for example
the genera Lebetanthus (Arroyo, 1975) and ngja_(Moore and Scotter,

1976). There has been very little information on the paleoclimatology

15

of Isla de los Estados with regards to either the Mesozoic (U. Jurassic -
L. Cretaceous) or the Late Quaternary. The present study attempts to
begin filling the information vacuum for the Late Quaternary by first
reconstructing the vegetation history since the last Glacial, then by
deducing paleoecological inferences and finally paleoclimatological

inferences whenever possible from the information available.

CHAPTER II
METHODS AND TECHNIQUES

Collection of the Samples

Three cores composed of peat were obtained by Michigan State
University from the R/V ngg_Cruise 71-5, which was funded by the Office
of Polar Programs, National Science Foundation, while three other cores
have been sent elsewhere.

On 29 October, 1971 Core II was collected from a boggy heath
located on the narrow isthmus separating Puerto Cook from Puerto
Vancouver near the center of the island's eastern sector (Figure 1).

Its collectors were Dr. Karl Ohlsson and Dr. Garrett Crow, at that time
graduate students from Michigan State University. The specific location
of this 4.51 m core was about 100 m from the north shore of Puerto
Vancouver. Core I (not studied) was collected at the same locality.

Core 111 was obtained by Dr. Henry Imshaug and Mr. Karl Ohlsson,
of Michigan State University, on 1 November, 1971 from a boggy heath.
Its location was in a valley between the first two hills northeast of
a stream mouth at the head of Puerto Celular (also known as Punta
Delgado), near the center of the island (Figure 1). In drilling the
core, the collectors occasionally encountered water pockets, and at the
bottom they struck a rock (or bedrock) 3.05 m below the surface. The
last core section contained white rocky material which appears to have
been derived from the Jurassic porphyritic bedrock. Cores IV and V

were also collected at the same locality, but they were not analyzed.

16

17

FIGURE 1

MAP OF ISLA DE LOS ESTADOS

cacao—no.3.

 

ON 0. O
0
.-::oo
, DauCQE
co>aooco> -
0:03.. ___ 0500
.1
__
flunv
4\ nv
x000

0...:a

‘

o..o.u>.oaao
a_n_

O

_\r 05.0nv

>o_uoo.u
0.:un

mon<hmm
m3 mo 52.

18

On 11 November, 1971 Karl Ohlsson and Garrett Crow obtained

Core VI from a Marsippospermum meadow on the east end of Bahia Crossley

 

about one-quarter mile (.4 km) inland from Bahia Teniente Palet and
about fifty meters from the farthest dune from the shore (Figure 1).

The corer could be driven no further than 9.63 m, and the bottom section
of the core had some granular material indicating the possible presence
of bedrock just below. Certain short sections of the core contained
only water or watery peat. Core VI differs from the others in that it is
in the area of underlying Jurassic-Cretaceous sedimentary deposits
composed of shales and black muds (Figure 1). All cores were obtained
with a Davis peat sampler by alternating between two holes six inches
(15 cm) apart and bringing the peat to the surface in one-foot (.3 m)
sections. The cores were immediately frozen, and the three cores
described above, out of a total of six cores taken on the expedition,
were sent to Michigan State University wrapped in aluminum foil. The
present author was not part of the scientific team which superintended

the collection of the cores.

Preparation and Mounting Techniques

When the frozen cores reached Michigan State University, one-
inch (2.5 cm) segments were cut out from the larger one-foot (.3 m)
lengths, and a sample was removed from the center of each segment using
a 9 mm cork borer. Each slug was extruded into the sample vials and
the remaining segment inserted back into the core, re-wrapped, and
returned to the freezer. According to the field notes, Core II was to
contain fifteen one-foot lengths, but only fourteen were located in the

laboratory. All other cores were complete, except for the fact that the

19

first one-foot (.3 m) section from each drill site was not collected,
and the second one-foot (.3 m) section of Core VI came to the surface
empty.

The individual peat samples were prepared using a standard
processing procedure for peat samples as outlined in Appendix A. The

samples were processed by several experienced students1

in the Michigan
State University Palynology and Paleobotany Laboratory, under the
direction of Dr. Aureal T. Cross and Dr. Ralph E. Taggart, and records
of the sample preparation were duly registered in the log books kept
permanently in the laboratory. The processing consisted basically of
boiling the peat samples in 5% KOH in order to free the pollen from the
matrix. The mounting consisted of placing two drops of melted
glycerin jelly with residue on a coverslip, placing the slide on

the cover slip, and then on a slide warming tray to cause it

to spread evenly. Since the glycerin jelly mount is sensitive to

air and moisture, it had to be sealed off by a thin band of finger-

nail polish around the outside edge of the cover slip.

Identification of the Palynomorphs
The main reference tools utilized in the identification of the

palynomorphs were Pollen anngpores of Chile by Calvin J. Heusser (1971)

 

and Pollen Flora of Argentina by Vera Markgraf and Hector L. D'Antoni
(1978). Both of these works have keys to aid in the identification of

unknowns in addition to photographs displaying the pollen and spores in

 

1The author did not participate in the laboratory processing
and mounting of the samples, although he has had experience in the
preparation of similar samples.

20

equatorial and polar views as well as at high and median focus for
detecting diagnostic exine elements.

Because Heusser (1971) described nearly 700 pollen and spore
types and Markgraf and D'Antoni (1978) nearly 400, it was advisable to
narrow down the potential palynoflora for Isla de los Estados to those
plants found growing today on the island or elsewhere in Tierra del
Fuego. For that purpose the "Index to the Flora of Isla de los Estados"
by Dudley and Crow (unpubl. ms.) served as a framework into which the
pollen and spore flora could be incorporated. However, the peat samples
contain taxa which are not found represented on the island today, either
due to long-distance transport of pollen (such as Ephedra) or to possible
fluctuations in the phytogeographical range of certain taxa. Thus it
was necessary to widen the scope of potential taxa that could be
represented to include those whose range today extends south of the
Strait of Magellan. The "Cataloga de las Plantas Vasculares Nativas
de Tierra del Fuego" by D. M. Moore (1974) has proved most useful in
that respect as well as "The Alpine Flora of Tierra del Fuego" by
D. M. Moore (1975). Most of the genera listed by Moore are illustrated
in either Heusser's or Markgraf and D'Antoni's reference works cited
above.

For the identification of those genera not illustrated in the
above two works use was made of the modern reference collection consisting
of mounted slides in the Michigan State University Paleobotany and
Palynology Laboratory, which has pollen from many species representing
most families of flowering plants of North and South America. Generally

less than two percent of the palynomorphs had to be placed in the

21

"unknown" category. This category also includes those which were
unidentifiable because of poor preservation or because of their being
partially obscured from view by detritus. Viewed as a whole, the
actual number of rare or exotic palynomorphs which could not be
identified was less than one percent of the total. Additional aids in
the further identification of the unknowns have been Erdtman's 2911531

Morphology and Plant Taxonomy (Erdtman, 1966); Pollen Flora of Taiwan

 

 

(Huang, 1972); Key to the Quaternary Pollen and Spores of the Great

Lakes Region (McAndrews, Berti, and Norris, 1973); and Pollen Analysis

 

 

(Moore and Webb, 1978).
All identification was done on one of two similar Leitz Ortholux
microscropes (serial numbers GGZ669 and 59l962), using the 54 X and

95 X objectives requiring oil immersion for observance of maximum detail.

CountinggTechnigues

 

Generally a total of 200 pollen grains and spores were counted
from each sample, though occasionally the count was increased to 250
or 300. In a few cases the count was between 100 and 200 due to a low
pollen density in the residue. Any exceptions to the 200 count are
noted on the pollen diagrams. The count excluded spores, cysts, or other
entities from non-vascular plants, such as dinoflagellates, miscellaneous
algae, fungi, and bryophytes, although bryophyte and dinoflagellate
percentages based upon total pollen are recorded on the diagrams.

As one measure of insuring the validity of the counts, the
selection of the microscope stage coordinates to be used in counting was
done in a random fashion. First, the coverslip area was divided into

four rectangular quadrants which extended the full width; then, the

22
exact horizontal coordinate to be covered in each traverse was selected
from a "random numbers table". When the count reached 50 in one
quadrant, then a traverse in the next quadrant was selected until all
four quadrants were covered and the count totaled 200. Any palynomorph
whose geometric center passed outside of the counting zone was auto—
matically excluded from the total count.

Due to the dominance of the flora by Nothofagus, an attempt

 

was made to count the Nothofagus pollen in every sample, the exceptions

 

being those samples whose pollen density was too low for counting. In
the pollen diagrams where there is no information other than the

Nothofagus percentages for a given sample it means that the total pollen

 

and spores were counted, but not identified. In a few cases any unusual
or important taxa observed in the count are noted on the diagrams with
a plus (+) symbol. Pollen frequencies on the diagrams are relative,
i.e., they are computed in terms of percentages of the total count, and

not in terms of the absolute concentration of pollen in each sample.

Photographic Techniques

 

Photographs of selected pollen and spores were taken on a
Leitz Orthomat camera and microscope unit located in the Michigan
State University Paleobotany and Palynology Laboratory. All photographs
were taken under the two highest magnifications using oil immersion,
unless the palynomorph was too large for the field of view, such as
some specimens of Armeria. Kodak Panatomic-X film was used. This was
developed using normal darkroom procedures. Representative pollen and
spores are illustrated in Plates 1 - 5 at 1000 X magnification, unless

otherwise noted.

CHAPTER III
RESULTS

The results of this study are summarized in three pollen and
spore diagrams (Figures 2-4), which are in terms of a relative pollen
frequency based on the total pollen and spores. Seventy taxonomic
groups are represented in total on the three diagrams. However, the
total palynoflora for Isla de los Estados would be even higher if
certain of the groups, such as the Ericaceae-type and the Compositae,
were broken down into their constituent and identifiable genera. For
example, Mutisia (Plate 3, Figure 3-10) of the family Compositae is
a component of the total flora, but does not appear on the pollen
diagrams. Nassauvia (Plate 3, Figures 3-11, 3-12, 3-13) of the Compositae
makes a somewhat frequent and regular appearance in the flora, but its
presence also is not noted on the diagrams. The pollen sum excludes
the spores or cysts of non-vascular plants, although the relative

frequencies for the dinoflagellates and bryophytes do appear on the diagrams.

Core 11
The Core 11 diagram representing Puerto Cook-Puerto Vancouver
in the eastern sector is comprised of approximately 45cflearly identifiable
taxonomic types obtained from l4 samples. The sample with the highest
diversity is Pb9731 at the base of the core, while the three samples with
low diversity are Pb9694, Pb9701, and Pb9712. Low diversity does not
appear to be connected with low relative percentages for arboreal pollen

frequencies. Diversity is high in samples Pb9724 and Pb9731 where the

23

24

FIGURE 2
POLLEN DIAGRAM FROM THE PEAT DEPOSITS OF THE PUERTO VANCOUVER-
PUERTO COOK ISTHMUS, ISLA DE LOS ESTADOS, ARGENTINA

Samples with only Nothofagus frequencies given are based
upon a pollen sum which includes total unidentified pollen
and spores and excludes entities of non-vascular plants.

 

 

 

24a

PUERTO VANCOUVER, ISLA DE LOS ESTADOS, ARGENTINA

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Core ll Latitude 54°47'S Longltude 64°04‘W
FERNS AND
TREES SHRUBS AND HERBS LYCOPODS
/ . 5 #7., /
0 :13” ,6 o I 75" Q) q,
Q o \ Q 4‘ a; C: \ 8 x
9’ ‘1’ w ‘1’ 3 {V :5 $0 6 5) I1; ”7'3 45“ q 5 \"7
0 ’17 r6 “1 s37 ' b \c .mm 7 b \.o (I’D '9 Q cc) :3
Q .1, b q, \ Q1 6 (q, 0.1,me 9) 0‘3 wraervzyoo eq§\ :60 o oob°cg(~
(v x (4.00 5 093, 0” q? a} ‘27\\q7,\a amass @‘Pkk gecequ O\§ cg 2: ¢\D§IyON°.OI
Depth Sample 306'? 057°C 8* g} .5 (53K? (.9 35’ f $5§§>§§U §§m§o§§§§g§gg§§§§®§§§§§gég§g «52$ ‘3‘? §§§Q§§A§ grains Zones
\ K ,7 .\ ‘ ~ '\ . x x x ‘\ -
(cm) No. e97 e7 6 0* 0 sec? ()0 a; 0 w‘RPszPd’ §§§eeasseeqfi°sg65$sieamomma <2? G ®Q°©S°oc counted
0
3
P69694 I r _ I 100
P096135 I I I — I 200 2
Pb9696 I l
D _
100— PhQGEIB I I - I I I 200
Pb9699 I
P697 I +
PDDTD‘I I _ — 200 1
Pb9702
Pnavos L M, ,,,,,,, !,..L-. A - — ,;_!<,,__ _ W I I l _,__gg#2_00__ _
P697 7’ TTTTTTTTTTT If T’"’_ TTTTTT "‘TTT"‘T"“ 7T7 ”TTT'I— ‘ _‘
Ph9707 I I - I 200 3
200‘ PDQTOB I
my I _ l I I I - 200 C
Pb97I0 2
Pb971‘ + +
Pusm _ I - + — - I 200 1
__ ,,,,,, I ,,,,,,,,,,, .-____ ______________________________ ~E_.E__,__L_EE_,E___,EE _,EL__, __-____._
P69715 I - I I _ l I 200
Ph9716 l
_ Pb9717 I +
300 Pb9718 I I I I I I I I 300 B
' Ph9719
Pb97 I
Pb9721 - I — - F 300
Pb9722 I
Ph9723 _# f 77777777777 #4 __ #Jkfi_fi ¥ *—
P69724 I —I I I T‘I‘T—“TTT"~__‘—__0TT I ‘ - I 200 3
Pb9725
4001 P69727 — I I I _ - — l I 150 A 2
Pnsm
Pb9730 + 1
Pb9731 l_ - I I I | | l 250
m ' W] ‘m m lllrlrlrlrlrlrlrlu]rlvrrrylrlrllIllultlrtrlrfltly rr—r—r‘r—l—[rr—l—lf—I—rI—r‘r‘m—l—l—Tj
20 4o 60 so 10 20 40 60 20 4o 10 1o 30 so 10 20 4o 60 1o 30 20 40 so 10 30 10 1o 10 1o 30 1o 10
l“"l . . POLLEN SUM: TOTAL POLLEN AND SPORES
10% + Denotes pollen or spores Observed In resrdue, but not included in pollen sum
(EXCL. NON-VASCULAR PLANTS)
W. H.Johns,1981

Figure 2. Pollen Diagram from the Peat of Puerto Vancouver, Isla de los Estados

 

 

25

FIGURE 3
POLLEN DIAGRAM FROM THE PEAT DEPOSITS NEAR PUERTO CELULAR,
ISLA DE LOS ESTADOS, ARGENTINA

Samples with only Nothofagus frequencies given are based
upon a pollen sum which includes total unidentified pollen
and spores and excludes entities of non-vascular plants.

 

1.14

 

 

 

25a

PUERTO CELULAR, ISLA DE LOS ESTADOS, ARGENTINA

FERNS AND
LYCOPODS

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Core III Latitude 54°48's Longitude 64°19'W
TREES SHRUBSAND HERBS
/—'——’———'47/ .. //’_'W
“4 q’$ «z; (I? Q a;
Q o .6 (‘5’.6 q 8 lo \\ k
e ‘11 A. o S .6 \ P A. o “’0 % S ’0
c9 0) {4% Q ‘a q, ,x x K \ I: Q m, g \
s as” es“ mi” 3°53" a? are a, c° é” a” obawsii-svaio e$i§§§§§§
(0 (”a ("o sogmqpa on, 052 wk g3 owgvsmceomgqu$o§§§coogNo.ol
Depth Sample 3°04? $049 {9&3 .5001“ $5005) \ 337‘ 59,6” 6° ~° §8§§§6h§§a§b°§éa8°$o §$§§§Q~5§grainsZones
(cm) No. gs e05 go §é§q° 04.0“” $7?” 0°45 0° 3 $$§om§§o°$§$¢<694¢ 427% G$© 56‘ co tea
0 I
P129676 - - I I —-I I I 182
C
Pb9618 —
100— P179650 — I — - - - 250
P996?" — I _ —
B
I 300
200— g
_ — + I I I l - 200
‘ I 200
I 7”“ "TI-T — - - +T"T "T‘ __'_+'TT_‘ 3.06"
— A
- _ — I - I I 200
+
300 I — I _ I 300
W‘TTT‘ITFl—TTT'DI’W—TT‘ WW’WWWWWWWWWWWWTW ri-rriflrr‘rv-t
10 so 50 7o 90 20 10 so 50 70 10 1o 10 20 4o 60 20 40 7o 20 1o 10 10 m 10
POLLEN SUM- TOTAL POLLEN AND SPORES
' ‘ in in I nsum '
+ Denotes pollen orspores observed In resrdue,butnot cluded pol e (EXCL. NON-VASCULAR PLANTS)
W H..Johns,1981

|—’_l
10%

Figure 3. Pollen Diagram from the Peat of Puerto Celular, Isla de los Estados

 

26

FIGURE 4
POLLEN DIAGRAM FROM THE PEAT DEPOSITS EAST OF BAHIA CROSSLEY,
ISLA DE LOS ESTADOS, ARGENTINA

Samples with only Nothofagus frequencies given are based
upon a pollen sum which includes total unidentified pollen
and spores and excludes entities of non-vascular plants.

 

 

26a

Longitude 64"42'W

BAHIA CROSSLEY, ISLA DE LOS ESTADOS, ARGENTINA

Latitude 54°48'S

Core VI

FERNS AND LYCOPODS

SHRUBS AND HERBS

TREES

 

Depth Sample

grains Zones
counted
150

 

 

 

A

 

143

200

300
200

150

200

300

zoocg

400

200

300
300
200

200

300
200
300
300
200

 

No.

(cm)

 

 

 

 

 

 

l

_7___.._..—»_—_.—-._—.—,_.__..

 

 

___.-.____._.___.,____u._
1_I__III____,

VFW—F
20
POLLEN SUM TOTAL POLLEN AND SPORES

 

 

4__ti._T,_-u,_,V

 

 

 

 

 

 

 

 

”79737

Pb9736

+

LI7‘.«Aliu—vg7.e__I0I,_1_I_V$

——4#~~»—AI__I,_..I..-»_.____I__u,A_._1.._,____‘____I__.._.___

 

 

Pb9740

PDQ"! _

l
Pb9742 F

PDQ?“
Pb9745

P139747

“79748

”29749

Pb9750
PMTSI

Pb9752
PD9753

.I,_I,,E.-H,,,,,,L ,,___,<_,_,h,fi,,,,_

 

Pb9754

Pb9755

PDQ?“

Ph9757

”39758

 

E
s
,
E
7
_
_
E
,

 

P119759
M780
PBQIGI

PW762

PDQTE

3

u
7
m
P

Pb9785

w

7

m

—
P691“ —

PMTSI

Pb9770

”29771

 

Pbfl773
PM"!

P179775

Phone —

Pb9777

Pb9780
M781

PUBTTD

 

04

100—

200 a

400 q

500—

_
0
0
6

700—

4

 

  

 

'I’I'l'ITT‘I'l'l'l'l‘l'l'l'l'l'l'l'l'lmW—l—T—l—‘Tl’r'm
1o

10

10

10

10

10

50

30

+ Denotes pollen or spores observed in residue, but not'included in pollen sum

W. H. Johns. 1981

(EXCL. NON-VASCULAR PLANTS)

m
10%

Figure 4. Pollen Diagram from the Peat of Bahia Crossley, Isla de los Estados

 

BI

Emp
Gun‘

be {

nan:
than
Pter

Imp?

27

arboreal pollen is only 2% and 0 respectively.

The major pollen contributors fall into ten taxonomic groups,
all of which have relative percentages equal to or greater than 10% at
some point in the core. Four other taxa have percentages ranging from
2% to 9% in at least one sample, while the remaining taxa all contribute
less than 2% to the total pollen influx. Consistently, the greatest
contributor is Nothofagus, which dominates the interval from 3.6 m to
1.0 m. Second in importance are the pterophytes, followed by Compositae,
Empetraceae (including some Ericaceae and Epacridaceae), Gramineae and
Gunnera, all of which are found in every sample. Consideration should
be given to what I have called the ephemeral dominants, those taxonomic
groups which achieve dominance only temporarily and then wane to insigni-
ficance or disappear entirely from the record. The two ephemeral domi-
nants are Cyperaceae and Astelia, both of which reach maxima of greater

than 50% prior to the time when Nothofagus begins to become dominant.

 

Pterophytes clearly dominate only in sample Pb9712. although they are
important contributors elsewhere. The Compositae achieve a clear
dominance in Pb9709 and a lesser role in Pb9701. The only significant
maxima in the Ericaceae-type pollen, which includes Empetraceae, are
in zone 0, where peaks occur in samples Pb9701 and Pb9694, the latter
one being its point of greatest dominance.

A description of the pollen zones is briefly summarized here,
while the interpretation will follow in the next chapter. Zone A of
Core II is characterized by unusually low Nothofagus percentages of
O - 6%. It is subdivided into A-1 where the Cyperaceae are clearly
dominant, A-2 where Cyperaceae, the Ericaceae-type, and Blechnaceae-

Polypodiaceae are the chief contributors, and A-3 where Astelia

28

is dominant. In zone B Nothofagus has values that generally exceed 40%

 

and at one point reaches 83%, thus dominating all other taxa. Zone C

begins with Nothofagus just under 25%. It is subdivided into C-l in

 

which the Pterophyta are preeminent, C-2 in which the Compositae are

slightly dominant, and C-3 in which Nothofagus rises to a peak of 83%

 

again. The youngest and longest of the zones is D, which is subdivided

into 0-1 with a strong Nothofagus dominance accompanied by a rise in the

 

Ericaceae-type pollen, 0-2 with a Nothofagus-Gunnera association, and

 

0-3 with another rise in Ericaceae-type pollen. Zone D-2 has also a
peak of the ephemeral dominant, Astelia, which attains 18% relative
frequency.

In noting over-all trends in Core II between competing or

conjoined taxa, it is found that the trend of Nothofagus is usually the

 

inverse of Pterophyta, and the trends of the Compositae and Ericaceae-

Empetraceae are more often in tandem than in competition.

Core 111

The shortest of the three cores, Core III, which was obtained
near the geographical center of the island, has eight samples that
provide the framework for the diagram (Figure 3). Diversity of the total
flora appears to be roughly proportional to the number of samples sur-
veyed; thus, Core III has a total flora of about 30 identifiable taxa,
compared to 45 for Core II. Diversity is not always related to
arboreal pollen frequency, because the three samples, Pb9685, Pb9691,
and Pb9693, having the highest diversity with at least l3 taxa contain

contrasting high and low Nothofagus percentages. In spite of its low

 

diversity, Core 11 contains four taxa not reported from the other two

cores, Alstroemeriaceae, Armeria. Koenigia, and Podocarpus.

29

Like Core II to the east, Core 111 has the ephemeral dominant,
Astelia, at the base of the core, but unlike Core 11 Cyperaceae cannot
be considered in that category. However, Ericaceae-Empetraceae appear
to have become an ephemeral dominant in the upper portion of the core.

Core III can be readily divided into the following three major
zones: zone A characterized by values of Astelia from 43% to 62%,

zone B where Nothofagus clearly dominates with 71% to 91% of the total

 

pollen, and zone C where Ericaceae-Empetraceae are dominant with a peak
of 71%. To further define any specific trends among the individual

taxa is not possible until more samples are available.

Core VI

Core VI, has a length of 9.6 m, which is twice the length of
Core 11. This was collected from the western end of Isla de los Estados
at the eastern end of Bahia Crossley. The pollen diagram (Figure 4)
shows a total diversity of about 50 distinguishable taxonomic types
based on 45 samples, which suggests that the increase in diversity is
due to a larger number of samples than the previous two cores. The
individual samples also have a higher diversity than the average for
individual samples of Cores II and III, the one exception being Pb9731
in Core II with the highest diversity of any sample studied. Diversity
does not appear to be linked with changes in arboreal pollen percentages.
For example, high diversity occurs in sample Pb9786 where the arboreal
pollen (AP) content drops to its lowest percentage occurrence in the
entire core, 2.6%. High diversity occurs also in samples Pb9769 and
Pb9779 where total arboreal pollen reaches 48.5% and 47.3% respectively.
Diversity is also quite high in Pb9763 where the arboreal Drimy§_attains

its highest percentage and where total arboreal pollen stands at 58%.

30

The major pollen contributors fall into nine taxonomic groups,

(Nothofagus, Gramineae, Compositae, Ericaceae-type, Gunnera, Astelia,

 

 

Blechnaceae-Polypodiaceae, Gleichenia, and Hymenophyllum-Grammatis).

 

Of these, Astelia and Hymenophyllum-Grammatis should be considered as

 

ephemeral dominants, each of them having a single peak. Three taxa
contribute from 5% to 10% pollen at most to the total spectra, and the
most stable and persistent of these are the Cyperaceae. One taxon,
Samolus, peaks at 15% in Pb9762, although it attains less than 2%
frequency in all other samples. Approximately thirty-five taxa contri-
bute less than 5% of the pollen, and by far most of these contribute
less than 2%. Besides these thirty-five minor contributors, there are

other minor contributors not listed separately, such as Lebetanthus,

 

which has been included with the Ericaceae-type pollen on the basis of
its similar tetrad structure.

The over-all trends can be best described in terms of the pollen
zonation summarized in Table 4. Five major zones can be recognized,

the boundaries of which have been determined by the Nothofagus maxima,

 

or peak values. Boundaries occur just above the maxima at Pb9788, Pb9775,
Pb9763, and Pb9752 as also denoted in Figure 4. Four full zones (B—E) of

Nothofagus cycles can be identified in Core VI, in which the repeating

 

pattern is a gradual increase of Nothofagus relative frequencies to

 

maximum values followed by an abrupt decline. Each zone boundary is

determined by this abrupt Nothofagus decline.

 

Zone A is the shortest of the five zones because presumably it

may be only the upper portion of a Nothofagus cycle. It is assumed

 

that if the pollen spectrum could be extended by retrieval of further
peat samples below sample Pb9790 at the base of Core VI, it would depict

31

TABLE 4

POLLEN ZONATION FOR CORE VI, BAHIA CROSSLEY

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

_ E-3 Compositae
—~1 m
' “J E-2 Nothofagus - Hymenophyllum
P2 m g
C
N
3 m E-l Ericaceae-type dominant (some Compositae,
- Nothofagus, and Pterophyta)
D-2 c. Nothofagus
"4 m b. Compositae
‘3 a. Ericaceae-type
. d)
C
° b. Astelia
-5 m “I 0'1 a. Ericaceae-type
» C-3 b. Nothofagus
a. Compositae
t’5 m L> C-2 Gramineae - Nothofagus
r ,5 C-1 Nothofagus - Compositae
-7 m
‘ c. Nothofagus
B-2 b. Compositae
”'8 m a; a. Nothofagus
8
" N
B-l Pterophyta - Ericaceae-type (with some
"'9 m Gunnera, Compositae, rising Nothofagus)
' < A Nothofagus dominance

 

 

 

32

a gradual increase of Nothofagus percentages toward Pb9790. At least

 

a Nothofagus forest would not be apt to appear suddenly as a mature

 

forest in the pollen record. In zone A Nothofagus reaches a relative

 

frequency of 71%, which is the highest for any sample in Core VI.

Zone B is characterized by a steady increase of Nothofagus

 

relative percentages from almost a complete absence of Nothofagus 90119"-

 

Sample Pb9786, which is second from the base of zone A, has a relative

frequency of 2%, which is the lowest for Nothofagus in Core VI. The

 

top portion of this zone has a strong Compositae maximum followed

immediately above by a Nothofagus maximum.

 

Zone C begins with a Nothofagus-Compositae association which is

 

interrupted by a sharp, but brief, influx of Gramineae. The top portion

of this zone returns to an almost identical Nothofagus-Compositae

 

association that appeared previously. Zone C concludes with the rise

of Nothofagus to another maximum and the waning of Compositae.

 

Zone D begins with the rise of Ericaceae-type pollen to its
first dominance in Core VI, followed by the relatively rapid rise of
the ephemeral dominant, Astelia. The remainder of zone D is character-

ized by the presence of Nothofagus at relative frequencies from 26% to

 

57% accompanied by another influx of Ericaceae-type pollen, after which
a notable Compositae maximum occurs. The end of zone D is marked by a

Nothofagus maximum of about 40%.

 

Zone E begins with a lengthy and apparently stable period when

the Ericaceae-type dominate. It is followed by a time when a Nothofagus-

 

Hymenophyllum association is dominant, the only example in Core VI when

 

fiymenophyllum makes a strong appearance. This zone ends with the Com-

 

positae reaching their highest peak in the core with over 70% of total

33

pollen and spores.
The over-all trends can be summarized as follows:

1) Nothofagus fluctuating in cycles from maxima to minima,

 

characterized by a gradual rise to maximum values and
a relatively rapid decline to minimum values,

2) Gramineae being fairly stable at values revolving
around 10% except for sharp pulse to 46.5% in
zone C-2,

3) Compositae usually fluctuating in an inverse

relationship to Nothofagus,

 

4) The Ericaceae-Empetraceae, Gunnera, and Pterophyta
sometimes paralleling the trends of each other as in
zone B, but sometimes trending in opposite directions
as in zone E.

More than passing notice should be given to the fact that

three of four Compositae maxima (Pb9754, Pb9765-7, and Pb9777) all
occur just prior to Nothofagus maxima (Pb9752, Pb9763 and Pb9775),

 

providing added evidence for the cyclical nature of the zones. The
larger questions of why this occurs and what implications it might have
in terms of possible climatic cycles or vegetational succession will

be dealt with in the next chapter.

Comparisons between the Three Cores

 

The over-all trends of the Nothofagus percentages can be shown

 

to roughly parallel one another in Cores II and VI if we assume the base
of Core II correlates with the 9.3 m level of Core VI represented by

sample Pb9787. (This must remain an assumption until such time that

34

radiocarbon dates become available to test its validity.) Zone A of
Core 11 then correlates with zone B-I of Core VI; zone B of Core II
with zones B-2 through C-3 of Core VI; zone C of Core 11 correlates
with zone D of Core VI; and finally zone D of the former correlates
with zone E of the latter on the basis of the Ericaceae-Empetraceae
maximum values in both.

Core III correlates with Core 11 best, which may be explained
on the basis that both are much closer to each other geographically than
Cores III and VI. Zone A in both cores seems to correlate well, espe-
cially in view of the fact that the ephemeral dominant, Astelia, is
found in both while it is not found in zone A of Core VI. Zone B of
Core III seems to correspond to zones B and C of Core II, but due to
a gap the correlation cannot be defined in any detail. Zone C of
Core III correlates with zone D of Core II, since the Ericaceae-
Empetraceae reach their peak in each of the two zones.

In addition to the over-all trends of Nothofagus, the strongest

 

basis for correlation among the three cores is the Ericaceae-Empetraceae
maximum in zone D of Core II, zone C of Core III and zone E of Core VI.
Whether this peak (which is composed mainly of Empetrum of Empetraceae)
is synchronous in all three cores needs to be substantiated by radio-
carbon dating, but this study will treat the matter as a working hypo-
thesis, which can be tested by some other lines of evidence.

The Astelia peak in the mid-section of Core VI (Pb9758) is not
considered to be correlative or synchronous with greater Astelia peaks
at the base of Cores II and III because the other pollen data contem-

poraneous with that peak do not correlate. Nothofagus in Pb9758 stands

 

at 34% while at the base of Core III it is less than 10% and at the

35

base of Core II it is 2% or less. Thus, Core VI has no Astelia peak
which can be synchronized readily with that of either Core II or Core III.
The Cyperaceae maximum at the base of Core II has no counterparts
in the other cores. A sharp Gramineae peak in Core VI at sample Pb9768
may correspond to a small Gramineae peak at Pb9712 in Core II; only
radiocarbon dates could help determine whether they are correlative at
this time. This further underscores the fact that the final determinant
in palynological and stratigraphic correlation of the three Isla de los
Estados peat deposits will be radiocarbon dating; thus, any cross-

correlations proposed should be considered as tentative.

CHAPTER IV
DISCUSSION

Towards a Paleoecological Interpretation

 

The key to the reconstruction and interpretation of some of the
plant communities of the recent past is the usage of modern-day analogs,
preferably from the same geographical locality as the cores. Fortunately,
extensive studies have been done and are yet in progress in analyzing
the present-day plant communities and their constituents for Isla de
los Estados (Crow, 1975).

The forested areas of Isla de los Estados represent an extension
of the southernmost forest in the world, the Magellanic evergreen forest,
which follows a narrow belt of high precipitation along the pre-
cordillera of the southwestern coast of South America (Young, 1972). To
the east of the cordillera, which is the southern extension of the Andes,
the precipitation levels fall off dramatically, as for example at
Punta Arenas, where the mean annual precipitation is one-sixth that of
the Grupo Evangelistas of the rain forest belt of the outer islands,
even though Punta Arenas lies just a few kilometers from the rain forest.
In addition to having high rainfall, the rain forest is characterized
by very low differences between summer and winter mean temperatures,
thus having a lack of seasonality, while just to the east of the
cordillera there is a more pronounced seasonality. Extremely low sub-
freezing winter temperatures are not recorded along the rain forest belt

(which includes Isla de los Estados), but they do occur on the eastern

36

37

0eeward)side of the cordillera. This is reflected in the fact that
most precipitation comes in the form of rain rather than snow, even in
winter. The Grupo Evangelistas record a mean annual number of days with
snowfall as 20.3, while 289 days have precipitation greater than 1 mm
(Miller, 1976). Isla Observatoria just a few miles north of Isla de

los Estados records 249 days per year with appreciable precipitation,
and probably would have a comparable snowfall profile (Meteorological
Office, Great Britain, 1958).

While there are up-to-date phytogeographical maps available for
a pictorial summary of the vegetation formations of southern Patagonia
(Arroyo, 1975; Young, 1972, Heusser and Streeter, 1980), the author
has chosen to give a verbal summary based on two recent summaries, the
one for all of southern Patagonia (Moore, 1978) and the other for
Isla de los Estados (Dudley and Crow, unpub. mss.). These recent studies
are erected on the foundation laid by C. J. F. Skottsberg, whose
exhaustive treatment of the Magellanic region remains untranslated from
the German (Skottsberg, 1916, cited in Moore, 1978).

The major vegetation zones, which roughly parallel one another
and parallel the coast, are largely determined by the topography and
the unique climate. The topography is characterized by the southern
extension of the Andes along a narrow belt just east of the outer
islands of the Magallanes, and, in the southern portion, the cordillera
itself drops below sea level to form the inner islands with rugged
shorelines and an intricate system of fjord-like inlets and channels.
Geologically, the cordillera is an anticlinal fold slightly overturned

to the northeast which was formed during the main Andean uplift in

38

mid-Cretaceous times resulting in a slaty cleavage axial, that is,
planar to the fold (Dalziel gt_al,, 1974; Palmer and Dalziel, 1973).
The axial-plane cleavage has been cut by granite intrusions occurring
in post-Albian and pre-Coniacian time of the Cretaceous. In Tierra del
Fuego the batholith forms the core of the Cordillera Darwin, while to
the west the outer islands are composed of basement schists of possible
Paleozoic age. The mechanism for uplift is the collision of the
westward moving South American plate with the Antarctic plate. To the
east and north of the uplifted areas Isla Grande of Tierra del Fuego
consists of a low, flat-lying plain containing post-orogenic Upper
Cretaceous sediments as well as Tertiary sediments.

Climatologically, the outer islands are subjected to constant
rains, high humidity, strong incessant westerly winds, and comparatively
moderate temperature fluctuations about the mean, both diurnally and
annually. The moisture-laden winds rise as they cross the cordillera
and thus heavy precipitation results, which feeds the glaciers in the
high elevations. (The author is not aware of any reported existing
glaciers in Isla de los Estados, however.) To the northeast of the
cordillera, a rain shadow is formed with a steep rainfall gradient in
just a few miles, which has a profound effect on the vegetation.

The major vegetational belts, as classified by Skottsberg (1916)
and as summarized in Moore (1968, 1975, 1978, 1979) and Young (1972),
are as follows:

1) Magellanic moorland. Due to the exceptionally strong winds,

 

high rainfall and the poor drainage on the Andean diorites of the
batholith, only a plant community of dwarf heath shrubs, cushion plants,

sedges, and bryOphytes can thrive. Nothofagus is found mainly in the

 

39

sheltered coves. At various localities Astelia, Caltha, Acaena, Empetrum,

 

 

Myrteola, Oreobolus, and Marsippospermum can each be dominant or co-

 

 

dominant depending on local variables.

2) Evergreen forest. In a belt where the annual rainfall is

 

between 800 mm and 4000 mm Nothofagus betuloides assumes greater

 

importance as the precipitation rises, although it is intermingled
with Nothofagus pumilio in a mixed evergreen-deciduous forest when the
precipitation is just above 800 mm. The evergreen rain forest is unique

in that it is dominated by a single tree species, Nothofagus betuloides,

 

an evergreen member of the southern beeches. This dominance is
illustrated on the pollen diagrams by relative percentages often above

50% and even up to 92% for Nothofagus, largely that of Nothofagus

 

 

betuloides (Figures 2 - 4, especially Figure 3). The other member of

 

the evergreen forest, Drimys winteri, fills a lesser role in the under-

 

story of Isla de los Estados and is a minor contributor to the total
pollen spectrum, although in the northern reaches of the rain forest it
occupies the overstory and can become locally dominant (Young, 1972).
The evergreen forest extends from sea level to about 350 m,
while it tends to favor sheltered valleys and coves as it enters higher
elevations until at its upper limit it forms a "krumholz" of twisted,
dwarf scrub. Besides Nothofagus and Drjmy§_other constituents of the

forest are the tree fern Blechnum magellanicum, the shrub Lebetanthus,

 

and the epiphytic filmy ferns Hymenophyllum, Grammatis, and Serpyllopsis.

 

 

3) Alpine vegetation. Just above the "krumholz" of Nothofagus

 

 

antarctica the alpine vegetation in Tierra del Fuego begins. Timberline
generally lies between 550 and 600 m, although on the large mountains

it may occur as high as 700 m. Three main factors, exposure to wind, the

4O

presence of water, and the type of substrate, determine the nature of
the alpine vegetation. It is composed of the following four structural
variants:

a) The cushion heath, which can occur at elevations well below

 

timberline, is characterized above timberline by cushions of Bolax_often
over a meter high as well as by Abrotanella, Azorella, Caltha, Colobanthus,
Drapetes, and Plantago. At increasingly higher elevations the cushions
become more scattered and Bolax_loses its dominance, until at the upper

elevation limit of vegetation scattered cushions of mostly Saxifragella

 

are present accompanied rarely by Azorella or Cerastium.

b) The dwarf shrub heath often interdigitates with the cushion

 

heath and shares most of the plant species found in the cushion heath.
But along the edges of rock screes as well as on other well-drained sites
a well-defined shrub heath develops, which is dominated by Empetrum

and to a lesser extent by Pernettya and Myrteola. Species not shared

by the two associations are Cystgpteris fragilis and Senecio darwinii,

 

 

which are primarily found in the dwarf shrub heath when becoming members
of the alpine community.

c) The feldmark is located on large sections of rolling or
gently sloping ground littered with talus deposits. Most alpine plants
have a difficult time becoming established here, but it does provide the
unique habitat required by Nassauvia lagascae var. globosa and
Nastanthus spathulatus, which are found nowhere else in Tierra del
Fuego, and for ysnga, which often blankets the feldmark.

d) The alpine meadow flora is concentrated in areas where there

 

are permanent streams and seepage areas often derived from permanent

41

snow banks or glaciers. The rich and varied flora is composed of
some of the same genera found in the other alpine associations, such

as Abrotanella, Caltha, and Plantago, but it also includes some others

 

not mentioned as characteristic of the first three associations:

Acaena, Gunnera, Hierochloe, Lagenophora, Ourisia, Oxalis, Poa, Primula,

 

Tapeinia, and Viola. If the stream bank is composed of coarse soil,
then Cardamine, Epilobium, Hamadryas, and Nassauvia are likely to occur.
Poorly-drained areas flanking the streams may support a variety of

grasses and sedges (e.g., Carex, Carpha, Schoenus, and Uncinia of,

 

Cyperaceae).

4) Transitional forest. As delineated by Young (1972), this
occurs at the transition from the evergreen to the deciduous forest in
an eastward direction from the cordillera. Outwardly the transitional
and the evergreen forest resemble one another because of their dominance

by Nothofagus betuloides, but the eastern edge of the true evergreen

 

forest is demarcated by the disappearance of the shrubs, Philesia and
Tepualia, as well as the epiphyte flymenophyllum pectinatus and the

ground-dwelling Blechnum magellanicum and Gleichenia quadripartita.

 

 

Lacking these understory elements, the transition forest is characterized
by pure stands of Nothofagus betuloides of sometimes sizable proportions
and by little undergrowth and no vascular epiphytes.

5) Magellanic deciduous forest. This occurs as a narrow belt
between the eastern edge of the transition forest and the western fringe
of the steppe and sometimes penetrates into the steppe in isolated copses
along valleys. It is dominated by the summer-green beeches, flgthgf
fagus gumilio primarily and Nothofagus antarctica secondarily, in a

belt circumscribed by a mean annual precipitation from 400 to 800 mm

42

at altitudes from sea level to 600 m. At higher elevations as well

as higher latitudes Nothofaggs antarctica becomes increasingly dominant

 

because of its greater adaptive ability. Along the forest borders and

 

in clearings a shrub community of Escallonia, Pernettya, and Ribes
may develop in the moister habitats, and one occupied by Berberis,

Chiliotrichium, and Embothrium may be found in the drier sites.

 

 

6) Patagonian stegpe. The grass steppe occurs consistently
east of the cordillera and is dominated by the grasses, Festuca and
Stipa. Other graminoids associated with the community are Bromus and

Poa. Non-graminoid members are most often Acaena, Calceolaria,

 

 

Hypochoeris, Relbunium, Verbena, and Vicia. In wetter sites such

 

graminoids as Alopecurus, Carex, Deschampsia, Juncus, and Phlggm_are
found, and a dwarf shrub heath dominated by Empetrum is found on the
shallow acid soils.

Five of the six major vegetation types as outlined for southern
Patagonia occur on Isla de los Estados, the Patagonian steppe being
totally absent. The reason for its absence is readily apparent when
one examines the rainfall data. To the north Rio Gallegos and Rio
Grande, Argentine, have annual precipitation levels of 281 mm and
379 mm respectively (Chapter I, Table 2), and both are located in the
Patagonian steppe. The high precipitation levels of Isla de los Estados
do not allow for the development of steppe.

Seven vegetation formations have been recognized on Isla de los
Estados, according to the work of Dudley and Crow (unpub. ms.). In
addition to the first five described above for all of southern Patagonia,
these authors include a littoral vegetation and a maritime tussock

formation. The littoral vegetation has elements of the meadow flora

43

and the Magellanic moorland, while the maritime tussock formation

consists of a single dominant species, Poa flabellata, that fbrms large

 

tussocks on the high bluffs and headlands along the coast. The scrub
formation described by these authors appears to be the "krumholz" of the
evergreen and deciduous Nothofagus forests at the higher elevations,
thus it can be considered as a subunit of either the evergreen or the
deciduous Magellanic forest.

The seven major vegetation formations on Isla de los Estados
described by Dudley and Crow (unpub. ms) have been schematized by the
author in tabular form (Table 5). The representative flora has been
given for each formation and in some cases for each subunit of the
formation. They are listed by their generic names only, since it is
usually impossible to carry their identification to the species level
when studying them palynologically. These modern-day vegetation
reconstructions will be used as the groundwork for reconstructing the
plant communities of the past by utilizing the information collected

from a pollen-analysis of the three peat cores.

Interpretative Problems and Possible Solutions

Before a reconstruction of the plant communities for the post-
glacial period can proceed, consideration must be given to the major
gaps that exist between the present and the past and to the difficulties
involved in bridging those gaps. As long as those difficulties are kept
in mind, then the temptation to stretch the pollen data further than is
legitimate will be avoided. The investigator will not extract more
information than is available in the pollen data, and the reconstruction

of the vegetation history over the past several thousand years will not

44

TABLE 5
VEGETATION FORMATIONS 0F ISLA DE LOS ESTADOSa

Littoral vegetation

 

a. Supratidal cushion plants - taking root in soil-filled cracks
of the rocky shoreline

 

Colobanthus - two species Plantago
'Crassula Egg.

b. Peaty surface just above rocky shoreline

Apium Ranunculus
Cotula Senecio - two species
Gunnera

c. Cliff face plants - overlooking the sea

 

Azorella Crassula
Colobanthus Ourisia
Cotula Senecio

d. Shoreline shrub zone - occuring in sheltered bays

Escallonia - Dominant Ribes
Hebe

 

e. Sandy beaches

 

Acaena Hierochloe
Apium Juncus
Caltha Senecio
Cardamine

Maritime tussock formation - headlands and high bluffs overlooking
the ocean

 

Poa flabellata - single dominant species, known as tussock grass;
it forms clumps that often crowd out most other species

 

Occasionally the following are found:

Apium Cardamine
Blechnum Senecio

45

TABLE 5 (cont'd)

3. Evergreen forest formation

a.

True Magellanic evergreen rain forest - southern and eastern
portion of the island

Nothofagus betuloides - overwhelmingly dominant
Drimys winteri - other arboreal representative

 

 

 

Berberis fiymenophyllum - 2 species
Blechnum [ebetanthus
Grammatis Luzuriaga
Gunnera Senecio
Serpyiiopsis

 

Magellanic evergreen transitional forest - northwestern portion
of the island

Nothofagus
Drim 5
Few plants growing on forest floor

4. Scrub formation

a.

Nothofagus antarctica association (deciduous forest)
Pure stands of dwarfed fl. antarctica with little undergrowth
Nothofagus betuloides - Marsippospermum grandiflorum association

N. betuloides - predominant, forming impenetrable thicket
'M. grandiflorum - dominant ground cover

 

 

 

‘Berberis flymenophyllum
Cfiiiiotrichium Pernettya

 

5. Meadow formation

Marsipposgermum grandiflorum - singularly dominant, giving the
appearance of a grass meadow

 

As lenium Gunnera
Berberis Hymenophyllum
CHiliotrichium Nothofagus

 

 

Drim s Pernett a
Galium Ranuncqus

Senecio

46

TABLE 5 (cont'd)

6. Magellanic moorland formation - composed of many subunits

 

a. Empetrum rubrum association - most predominant subunit

Dominated by:

 

 

 

Empetrum

Marsipposgermum

Pernettya

Others that are present, but usually scattered in distribution:
Berberis Gunnera

Blechnum - 2 species Luzuriaga

Chiliotrichium Nothofaggs

Drimys Rubus

b. Caltha association

Caltha - 2 species dominant

 

Astelia Nanodea
Drapetes Perezia
Gaimardia Pernett a
Gaultheria Tribeles
Gunnera

c. Astelia pumila association - high elevations

 

A. pumila - almost pure stands formed

 

 

 

'Abrotanella Gaimardia

Azorella Gleichenia
Bolax Nothofagus
Caltha - 2 species Oreobolus

Drosera

7. Alpine formation - 450 m and below, lower limits variable

 

 

 

Abrotanella Nothofagus
Azorella - 2 species ‘Dreobolus
Bolax Pernettya
Caltha Poa
Drapetes Senecio

Em etrum Viola
Eymenopfiyllum

 

aSummary of the vegetation of Isla de los Estados adapted from
an unpublished manuscript by T. R. Dudley of the U. S. National
Arboretum, and G. E. Crow of the University of New Hampshire. This
is similar to, but an expansion of, the material found in Crow (1975).

47

be more precise than the precision limits inherent in palynology.
Following are the major interpretative problems (or gaps) and their
possible solutions (i.e., the ways in which the gaps can be bridged).

The lack of surface samples. One of the most important links
in spanning the gulf between the vegetation of the present and the
pollen of the past is the analysis of the pollen contained in surface
samples from the site under study. The advantage of surface sampling
is that it can be more readily determined which of the living plant
taxa are over-represented, which are under-represented, and which are
represented not at all in the pollen flora (a problem which will be
analyzed separately below). No surface samples were collected and
sent on to Michigan State University from the three coring sites.
Another method for detecting the modern pollen flora is to set up
aeropalynological stations and process the pollen from mostly anemo-
philous plants collected on oiled microscope slides over periods of
time. Since the stations must be in operation at all seasons of the
year in which flowers are in bloom, it would hardly be expected that
such stations would be set up during the short R/V flerg_cruise. It
would be advantageous for future cruises or botanical expeditions to
the island to collect aeropalynological samples, or at least to collect
samples from the surface of the substrate.

The problem of representation. If a plant ecologist were to
analyze each constituent member of the community according to its
relative contribution to the total plant biomass of the community, and a
palynologist were to analyze the modern sediments in order to determine
the relative contribution of each pollen and spore taxon to the total

palynoflora, and comparisonswere made of the two sets of data in terms

48

of relative percentages, one would find discrepancies in varying degrees
between most of the taxa. The problem is that of under-representation
and over-representation (or even non-representation) between the living
flora and the pollen flora. If the magnitude of the differences is
known between the two, then it is possible to re-interpret the pollen
diagram, so that values more representative of the actual composition
of the plant community would be given. The pioneer study along such lines
is now in progress for Argentine Patagonia. Markgraf, D'Antoni and
Ager (unpub. ms.) are relating the pollen flora from surface samples
with the existing vegetation patterns representative of the desert
regions of northern Argentina and the temperate forest and steppe regions
of southern Argentina as far south as Tierra del Fuego. A similar study
should be done for Isla de los Estados, but it will not be feasible
until such time as surface samples become available.

However, some generalized judgments can be made on representation
based upon available descriptions of the vegetation surrounding the
three coring sites. Berberis is represented at the sites of Cores II
and VI as an important constituent of the flora, but no Berberis pollen
grains were found in Core 11 and almost none were found in Core VI. This
seems to be a case of under-representation. Another example is Pernettya,
which is reported today from the vicinity of Cores III and VI, but was
rarely encountered in the cores themselves. The most outstanding

example of under-representation is that of Marsippospermum which is the

 

major component of the heath around Core III and the meadow around
Core VI's site. Only two or three palynomorphs which could be attributed
to Marsippgspermum were located in these cores. However, there may be

another problem involved here, that of preservation.

49

Another factor in non-representation or under-representation
is that non-anemophilous plants are at a distinct disadvantage compared
with anemophilous plants because they can only be represented in the
pollen record if the core penetrated the spot where the parent plant
once grew and where the pollen fell on the peat. Such is the case with
Armeria, which was found only in sample Pb9693 at the base of Core III.
Armeria should be much better represented in the pollen record based
upon its wide range today in a variety of habitats from alpine (Moore,
1975) to oceanic islands (Moore, 1968). It grows today in the vicinity
of Core 11, but its pollen has not been detected in that core, the
reason being that Armeria is self-pollinated, not wind-pollinated
(Moore and Yates, 1974).

The problem of greservation. A certain member of the plant

 

community may make a sizable contribution to the modern pollen spectrum,
but due to the biochemical composition of the exine or due to the nature
of the substrate, its pollen may become corroded or entirely destroyed

over a period of time. All of the Juncaceae, of which Marsipposgermum

 

is a member, seem to be characterized by a low durability factor

(i.e., poor preservability) perhaps due to the thinness of the exine
compared to the size of the pollen grain, or to its susceptibility to
corrosion in the weakly acidic peats. However, peat is considered to be
an excellent preserving medium for spores and pollen grains, especially
for Postglacial palynomorphs.

The problem of exotic pollen. Occasionally pollen grains appear

 

in the pollen record here which represent plants now known to grow at
considerable distance from the coring site. The answer to this problem

is not that its range once extended much wider than at present. Evidence

50

from other cores shows that its Postglacial range has differed little
from today‘s range. The probable explanation is that long-distance
transport is involved. Pollen of anemophilous plants is often lofted
into the air currents of the upper atmosphere or sometimes storms carry
the pollen far beyond their usual ranges. Ephedra has been found in just
two samples of Core VI (Figure 4), but it is not currently growing
anywhere on the island today. The nearest source area is the Patagonian
steppe of Tierra del Fuego. Thus Ephedra pollen probably was trans-
ported to the island by the prevailing westerlies, and has been detected
only in the core at the western tip of the island. It is reported in
the pollen record from several samples at the La Mision site, which is
located just north of Rio Grande of eastern Tierra del Fuego, but it

is never found in significant numbers (Markgraf, 1977).

One would expect the exotic pollen of Podocarpus to have been

 

found in several samples from Isla de los Estados, since it is found
in the majority of samples from the 9.2-m La Mision core approximately
225 km to the northwest, sometimes occurring in surprising numbers,
i.e., more than 10% of total pollen (Markgraf, 1977). It also has
been transported more than half way across the Atlantic to Tristan de
Cunha on the mid-Atlantic ridge and appears on the pollen record there

(Hafsten, 1960). However, only one grain of Podocarpus pollen has

 

been identified in the Isla de los Estados samples,being found in
Core III from the center of the island. This unmistakable example

of Podocarpus has been illustrated (Plate 1, Figure 1-15) and has

been noted on the Core III diagram (Figure 2). The reason for its
scarcity is simply that the prevailing winds there are south-westerly,

while it would take north-westerly winds to bring in Podocarpus,

 

51

which now grows north of the Magellanic Straits (Moore, 1974).

The groblem of pollen taxonomy. Pollen and spore taxonomy does

 

not reach the degree of exactness as does the taxonomy of the parent
plant, for the simple reason that the taxonomist is dealing with a
much smaller portion of the plant with an extremely small number of
diagnostic features compared to the whole-plant taxonomy. Very seldom
can the palynomorph be identified down to the level of the species.
Thus when an attempt is made to determine paleoecological associations,
a generic identification only cannot provide the information an
identification on the species level could. Some genera like Senecio,
592353, and Azorella contain species which vary from alpine representatives
to those that favor wet sites to those that tolerate drier sites;
therefore, their presence in the pollen record does not facilitate the
making of precise paleoecological and paleoclimatological interpretations.
Some palynomorphs cannot be safely identified below the level
of the family, such as Chenopodiaceae and Gramineae, thus making
paleoecological interpretations even less certain. Many of the genera
within Compositae, Cyperaceae, and Juncaceae are difficult to differ-
entiate. Therefore, they have been lumped together in their respective
families. Three heath families, Empetraceae, Epacridaceae and
Ericaceae, have very similar pollen usually occurring as tetrads, so
these have been considered as one taxonomic group on the pollen diagrams,
the Ericaceae-type. Yet the individual genera may have differing

paleo-environmental requirements, e.g., Lebetanthus of Epacridaceae

 

is usually associated with the Nothofagus forests and Empetrum of

 

Empetraceae with the Magellanic moorland heaths. Members of the

Polypodiaceae cannot usually be safely distinguished, and there is

52

possible confusion with the Gleichenaceae, so these facts must be kept
in mind when analyzing the pollen diagrams.

In order to differentiate the Magellanic evergreen forest from
the deciduous forest palynologically it would be advantageous to be

able to clearly separate taxonomically the pollen of Nothofagus

 

betuloides from that of M, antarctica, the two major components of

 

 

these forests respectively, but it is not possible to positively differ-
entiate between the two on the basis of the morphology of the grains. Heusser

(1971) suggests that the palynologist can separate Nothofggus into

 

only the two groups, the Dombeyi and Obliqua types. He states,
"Identification below the type level does not appear workable" (Heusser,

1971, p. 35). Unfortunately, fl, betuloides and M, antarctica both fall

 

 

within the same Dombeyi type. However, an attempt will be made below

to separate the two species of Nothofagus in a general fashion based

 

upon the differing ratios of the number of apertures.

In spite of these taxonomic difficulties, it is still possible
to extract a substantial amount of information from the pollen record
in making paleoecological and paleoclimatic reconstructions.

A Possible Solution to
Identification of’Nothofagus Pollen

 

The problem of the further identification of the stephano-
aperaturate Nothofagus pollen beyond the two types, Dombeyi and Obliqua,

 

may find its solution in the possibility that each Nothofagus species

 

has a different ratio of aperture numbers. According to Heusser (1971,

pp. 35, 36) fl. antarctica has 5 to 7 apertures distributed in the

 

following way: 5-3%, 6-50% and 7-47%, in contrast to M, betuloides

 

which has 4 to 7 apertures distributed as follows: 4-3%, 5-67%, 6-29%

53

and 7-1%. If one were to have a predominance of 5-aperturate

Nothofggus grains in a given sample accompanied by a scattering of 4-

 

aperturate types, then one would conclude that M, betuloides is the

 

dominant species represented in the count. Conversely, a predominance

of 6- and 7-aperturate Nothofagus almost to the exclusion of 5-

 

aperturate types would tend to confirm the identification of these as

M, antarctica. But the matter is not so clear-cut, because there is

 

generally a mixture of the two species, as indicated by contemporary
floras, and the two species occur in undetermined proportions in the
flora.

Besides fl, betuloides and fl, antarctica, the only other species

 

 

of Nothofagus currently growing on the island is M, pumilio. The

 

samples examined rarely contained fl, pumilio pollen which can be readily
identified by its more rotund appearance and its staining properties.
(It stains a deeper red color, possibly due to the susceptibility of

the exine to absorb safranin dye more easily.) For the purposes of our

 

Nothofagus differentiation, the possible effects of M, pumilio can be
ignored because of its negligible contribution (less than 2% of total

Nothofagus).

 

Dr. Ralph E. Taggart suggested that it would be possible to

differentiate the Nothofggus species mathematically based upon an

 

analysis of the numbers of apertures for all Nothofagus grains in a

 

given sample. He devised a computer program (Appendix B) for

differentiating M, betuloides from M, antarctica, and the following

 

 

step by step sequence is a description of the procedure.
The first step is to obtain an aperture count for all

Nothofagus present. Generally the Nothofaggs count had to be extended

 

 

beyond those identified in the minimum count of 200 pollen and spores.

54

Occasionally more than 1000 pollen and spores had to be counted in order

to increase the Nothofagus count to a statistically significant level

 

in a sample.
The second step is to determine the statistical probability for

a given Nothofggus pollen grain to be assignable to M, antarctica. This

 

may be accomplished only on the basis assuming that aperture ratios in
this species has remained unchanged during Postglacial time. The

aperture ratios given by Heusser, 5-3%, 6-50%, 7-47%, for y, antarctica,

 

and 4-3%, 5-67%, 6-29%, 7-1% for M, betuloides, indicate that for a

 

given 7-aperturate pollen grain, the probability is 50 times greater

that it is M, antarctica rather than M, betuloides. This means that

 

 

if fifty 7-aperturate pollen grains are counted in a given sample, only

one of those is to be attributed to M, betuloides. For all practical

 

purposes the effect of M, betuloides upon the 7-aperturate count is

 

negligible. The formula for obtaining the total fl, antarctica (TA)

 

is found by simply taking the total 7-aperturate Nothofagus count (T7)
of a given sample and dividing by 47%.
TA = T7/.47 (Equation 1)

The third step is to determine the contribution of M, betuloides

 

to the total count. This can be accomplished by analyzing statistically
the 5-aperturate count with the assumption that the ratios given by
Heusser hold true throughout Postglacial time. For a given number of
5-aperturate pollen grains the probability for the occurrence of M,
betuloides is 67:3, based upon Heusser's ratios. Here the contribution
of M, antarctica is slightly above the negligible level, and thus must
be computed. The total 3, betuloides pollen (TB) is calculated on the
basis of the total 5-aperturate count (T5) divided by 67%, after which

55

the contribution of N, antarctica is subtracted.

 

TB = T5/.67 - (TA X .03) (Equation 2)

The total N, antarctica (TA) has been derived from the previous formula

 

and is multiplied by 3% to obtain the relative contribution of N,

antarctica in the 5-aperturate count, due to the fact that 97% of

 

N, antarctica do ngt_have five apertures.

 

The fourth step is to determine how many of the Nothofagus

pollen grains cannot be attributed to either N, antarctica or N,

 

betuloides in the total Nothofagus count (TN). The total unknown

 

 

Nothofagus (UN) is derived from the total Nothofaggs (TN) less the total

 

N, antarctica and total N, betuloides.

 

 

UN = TN - (TA + T8) (Equation 3)
The figures for TA and T8 are obtained easily by the previous two
equations, and TN has been accurately tallied during the counting of

samples, being composed of all Nothofagus grains in a given sample

 

having an available aperture count. (Grains not counted in TN are those
which were partly blocked from view or which were folded.) Thus the

total of unknown Nothofagus (UN) can be easily derived.

 

To facilitate the calculations of the three equations, the
equations were incorporated into a computer program (Radio Shack TM
Level II BASIC) for use on a Radio Shack'TRS-BD Model I Microcomputer. The
computer program used in the calculations is found in Appendix B, and

the aperture data obtained from the Nothofagus counts is located in

 

Appendices C, D, and E. Much appreciation goes to Dr. Ralph Taggart,
of the Department of Botany and Plant Pathology, for writing the
computer program. The results provided by the computer tabulation are

found in Figures 2, 3, and 4 of Chapter III, where the relative

56

contributions of N, antarctica, N, betuloides, and unknown Nothofagus

 

 

 

to the total Nothofagus count are given.

 

An examination of the profiles from the three cores indicates

that N, betuloides is clearly dominant over N, antarctica. With only

 

 

three exceptions, Pb9685, Pb9687, Pb9721, from among more than 100
samples, the percentages for N, agtarctica_are less than 10%. (It
should be noted that the percentages given on the diagrams are based

upon total pollen and spores, not total Nothofagus pollen.) This is in

 

contrast to N, betuloides which reaches 50% of total pollen and spores,

 

or higher, in several samples. This disproportion between the two

Nothofagus species throughout the Postglacial period is confirmed by

 

the analysis of leaf and fruit macrofossils from the Mylodon Cave,
Ultima Esperanza, southern Chile, covering the Postglacial period
(Moore, 1978). A series of four radiocarbon dates starting with 12,496
B.P. gives the chronology of the dung deposits from the extinct ground
sloth, Mylodon, accompanied by a sequence of leaf litter deposits.
Although Ultima Esperanza is more than 400 km north of Isla de los
Estados and lies just outside the Magellanic rain-forest belt, the cave

deposits do indicate episodes of forestation with a mixed Nothofagus

 

evergreen-deciduous forest. During these episodes of forestation

N, betuloides was clearly the dominant species on the basis of the

 

presence of many more times the amount of plant remains than N, 335-
arctica. The latter reaches a small peak at mid-point in the interval
between 7803 and 5643 B.P., and an even smaller peak in the layer dated
to 2556 B.P. .N. pumilio usually fluctuates at levels midway between

the peaks of N, betuloides and N, antarctica.

 

 

The over-all patterns of variation of Nothofagus percentages

 

57

for Isla de los Estados do not correlate well with the profile at the
La Mision (Cabo Domingo) site as studied by Auer (1965, 1974). In
contrast with Ultima Esperanza and Isla de los Estados, the La Mision

diagram generally ascribes the lowest percentages to N, betuloides,

 

while the higher percentages alternate between N. antarctica and N,

 

pumilio. Auer's data may differ because he uses totally different
aperture percentages than does Heusser (Auer, Salmi and Salminen, 1955,

cf. Heusser, 1971).

One obvious result of the computer analysis of the Nothofagus

 

aperture data is that the "unknown" Nothofagus percentage in certain

 

samples is at higher levels than is desirable. As noted above, the
"unknowns" cannot all be attributed to N, pumilio, because one can

visually distinguish that pollen species from the other two Nothofagus

 

usually present. The "unknowns" would have to be attributed to N,

betuloides, N, antarctica, or to another species of Nothofagus not

 

 

 

extant on the island today. If the pore distribution has remained
relatively constant throughout the Postglacial period, and if no other
Nothofagus species has made a detectable contribution to the pollen
influx, then it is more likely that most of the "unknowns" are attribut-

able to N, betuloides because of the apparently greater contribution of

 

N, betuloides over N. antarctica according to the computer analysis.

 

However, the high levels for the "unknown" Nothofagus percentages

 

do call into question the accuracy of equations 1, 2, and 3 used for

the derivation of the N, antarctica and N, betuloides percentages. It

 

 

is thought that the equation for N, antarctica is fairly accurate because

 

it allows for low percentages of N, antarctica in comparison with N,

 

betuloides, which accords with the fact that a relatively low number

58

of 7-aperturate grains are found in the samples. Yet the number of 5-
aperturate grains does not conform with Heusser's percentages for N,

betuloides, suggesting that 67% have five apertures. In Core VI the

 

totals for the aperture counts along with their respective percentages

relative to total Nothofagus are as follows:

 

 

Four Five S15. Seven Eig t Nine Unidentified
106 2199 2081 221 9 1 336
2.3% 47.6% 45.1% 4.8% 0.2%

This represents the totals for the data found in Appendix E.

The number of Nothofagus with five apertures is less than 50%.

 

If nearly all of these are attributable to N, betuloides, then we have

 

evidence that Heusser's ratios derived from Chilean material may not
always apply. Unfortunately we have had no opportunity for analyzing
the pollen from living trees on Isla de los Estados to determine whether

the aperture percentages for N, betuloides should be modified slightly,

 

or whether the figures given by Heusser for Chile hold true for the
Island. It is possible that there has been some phenotypic variation

at differing geographical sites for palynomorphs within a given Nothofagus

 

species.

There are two means whereby we can test the accuracy of
aperture studies of fossil pollen and its application to taxonomic
identification. The first is to use the resultant data as a means of
prediction. We have determined the relative proportions of N,

betuloides and N, antarctica in our samples, especially in Core VI. We

 

 

should then be able to predict how many of the total number of pollen
grains should have a certain number of apertures. For example, the

data from Heusser would suggest that 3% of the total N, betuloides

 

59

should have four apertures. This means that of the total Nothofagus

 

in Core VI attributed to N, betuloides (4149 in all) approximately 124

 

should have four apertures. The actual total as given above is 106,
which is within the limits of statistical uncertainty. Thus the

percentages given for 4-aperturate N, betuloides by Heusser can be

 

validated throughout the last several thousand years in the Bahia
Crossley deposit.
A second means of testing the validity of the equations is to

compare the N, antarctica percentages with those of total Nothofagus.

 

 

This can be best accomplished by analyzing the relative percentages

of 7-aperturate pollen with respect to total Nothofaggs. As noted

 

previously most of the grains with 7 apertures can be attributed to

N, antarctica. A comparison between 7-aperture percentages in Core VI

 

with total Nothofagus percentages appears in Figure 5. I have reduced

 

the total Nothofagus to one-tenth the scale for the 7-aperturates. It

 

should be noted that the percentages for the 7-aperturates is based

upon total Nothofagus, while the percentages for total Nothofagus is

 

 

relative to total pollen and spores. The reason for this is that total

Nothofagus is a function of the paleoclimate, probably basically the

 

result of temperature changes. An increase in tree pollen, in this

case Nothofagus, can be correlated with an increase in temperature.

 

A close comparison of the 7-aperturate percentages with total

Nothofagus indicates that there is an inverse relationship. I have

 

reversed the direction of the 7-aperturate percentages in order to
accentuate this relationship in Figure 5. The inverse correlation
between the two sets of data is reasonable from a paleoclimatological

and paleoecological standpoint. Whenever there is a drastic decrease

Pb9733
Pb9737
Pb9736
Pb9740
Pb9741
Pb9742
Pb9744
Pb9745
Pb9747
Pb9748
Pb9749
Pb9750
Pb9751
Pb9752
Pb9753
Pb9754
Pb9755
Pb9756
Pb9757
Pb9758
Pb9759
Pb9760
Pb9761
Pb9762
Pb9763
Pb9764
Pb9765
Pb9766
Pb9767
Pb9768
Pb9769
Pb9770
Pb9771
Pb9772
Pb9773
Pb9774
Pb9775
Pb9776
Pb9777
Pb9778
Pb9779
Pb9780
Pb9781
Pb9782
Pb9783
Pb9784
Pb9785
Pb9786
Pb9787
Pb9788
Pb9789
Pb9790

60

FIGURE 5

NOTHOFAGUS ANTARCTICA PERCENTAGES

COMPARED TO

TOTAL NOTHOFAGUS PERCENTAGES IN CORE VI

7-aperturate Nothofagus (I)
l

1

Total Nothofagus (2)
SO

 

 

61

in mean temperature, as indicated by a drop in total Nothofagus, then

 

N, antarctica has an ecological advantage over N, betuloides. The

 

 

former is the hardier of the two and grows at higher elevations today,
sometimes forming low mats of "krumholz" near tree-line in the Magellanic

region. Also, it is deciduous, while its rival, N, betuloides, is ever-

 

green. A rise in mean temperature, as indicated by a rise in the total

Nothofagus percentages, gives an advantage to N, betuloides, especially

 

 

if the winters are warmer. The validity of equation 1, which proposes

a means of isolating N, antarctica as the major constituent of the 7-

 

aperturate pollen, is thus substantiated by the inverse relationship

between 7-aperturate pollen percentages and total Nothofagus pollen.

 

It is possible, therefore, to distinguish the Nothofagus pollen of Isla

 

de los Estados on the basis of a mathematical analysis of aperture

counts.

Paleoecological Interpretation for Core 11
(Puerto Cook-Puerto Vancouver)

 

 

For the paleoecological reconstruction, modern analogs will be
used based on the seven vegetation formations for the island analyzed
by Dudley and Crow (unpub. ms.). These formations are the littoral
vegetation, maritime tussock, evergreen forest, scrub, meadow,
Magellanic moorland, and alpine. Also, useful will be a detailed
vegetation analysis for the Falkland Islands (Moore, 1968), which has
a similar climatic regime, and which has many of the same plant for-
mations,such as the maritime tussock, the heaths. and the littoral
vegetation. The Falklands have a total of 163 species of native vascular
plants, compared to 170 for Isla de los Estados, but an important

difference is the absence of arboreal species on the Falkland Islands,

62

which are located 520 km east of the Strait of Magellan between the
latitudes of so°oo's and 52°3o's.

The vegetation history at the Puerto Vancouver—Puerto Cook
isthmus, the site for Core 11, begins with two distinctive, but
somewhat dissimilar, heaths found in zone A, and these are also

characterized by the virtual absence of Nothofagus. The pollen

 

diagram (Figure 2) shows first a strongly dominant Cyperaceae heath
(zone A-1) and then a strongly dominant Astelia heath (zone A-3)
separated by a transition zone (A-2) comprised of Cyperaceae, Ericaceae-
Empetraceae, Blechnaceae-Polypodiaceae, none of which achieve strong
dominance. The Cyperaceae of zone A-l is best paralleled by the

wetter subunits of the Cortaderia heath (pampas grass) association of

 

the Falklands where ngex_and Oreobolus may be co-dominant. At the
beginning of the zone, Gramineae is second in importance to Cyperaceae,
and Uncinia may be the major contributor to the Cyperaceae total, which
parallels the condition on the West Falkland Islands.

Zone A-3 is analogous to the Astelia pumila association of the

 

Magellanic moorland formation in view of the fact that it contributes

60% of the pollen sum and that the Nothofagus forest must have been

 

greatly limited. In that association Astelia is said to form dense
mats composed of almost pure stands of Astelia. It favors highly
mineral soils, especially soils freshly exposed through erosion
(D. M. Moore, personal communication). The two heaths of zone A,
which are characterized by strong dominants, thus parallel the
Magellanic heathland of the modern vegetation.

Sample Pb9731 of zone A-l has two special characteristics:

first it has the highest diversity for any sample in the three cores,

63

and second it has no Nothofagus pollen represented. Except for sample
Pb9730 which was taken just above it, no other sample out of more than

100 samples examined has a total absence of Nothofagus. To account for

 

this noteworthy absence, one could suggest that either there had been
no forests prior to that time due to the effects of the last glaciation,
or that forests had indeed existed just prior, but they had been deci-
mated and removed from the pollen record by either a single factor or
a combination of factors.

First, in consideration of the hypothesis of a deforestation
having occurred at the time of deposition of the two lowest samples
of Core 11 (Pb9730 and Pb973l), the main evidence hinges upon the
correlation of zone A here with the lowest portion (Pb9786) of zone B

in Core VI, at which point Nothofagus values are at their minimum for

 

any sample in the Bahia Crossley core, being only 2% of the pollen sum
(Figures 2 and 4). In Bahia Crossley this is clearly a case of
deforestation, because the preceding zone A has evidence of heavy
forestation. If samples Pb9730 and Pb9731 of Core II correlate with
sample Pb9786 of Core VI, then for consistency sake one would have to

argue that deforestation accounts for the lack of Nothofagus at the base

 

of Core II. In other words, at that point in time the eastern portion
of Isla de los Estados would have to be characterized by a lack of the
Magellanic forests, while the western portion must have had scattered
individuals or clumps of Nothofagus. The central portion of the island
would also have to be characterized as having had very low numbers of

Nothofagus if the base of Core 11 is correlative with the base of

 

Core III (Figures 2 and 3).

Another suggestion to account for the lack of Nothofagus pollen

 

at the base of Core 11 is that this zone depicts a flora that indicates

64

either Lateglacial or early Postglacial conditions. As noted earlier,
sample Pb9731 in this zone has the highest diversity of any sample out
of more than 100 examined in three cores. With 23 taxa represented, it
has 60% of taxa found in all the samples analyzed in Core II. In com-
parison with the three next highest samples in diversity, Pb9691, Pb9693,
and Pb9786, each of which 45% of the total taxa found in their respective
cores, there is no doubt that sample Pb9731 has the highest diversity.
The logical explanation is that this represents a pioneer community that
has entered the island relatively soon after deglaciation when competi-
tion would have been at a minimum.

Paleotemperature inferences from the pollen data of Alerce,
Chile (4l°25'S, 72°52'W) indicate that between 11,300 B.P. and 9410 B.P.
the mean January (summer) temperature was as low as 6°C below today's
mean, which was the lowest at that site for any time in the Postglacial
(Heusser and Streeter, 1980). A temperature 6°C lower than today's for
Isla de los Estados would result in a mean annual temperature slightly
below the freezing point (Table 3), preventing development of forests.

If the correlation of zone A in Core II with the 11,000 - 10,000
B.P. period of minimum temperatures inferred from the Alerce, Chile
record is valid, then it could likewise be characterized as a period
of higher precipitation than today's levels. Inferences from the
pollen data at Alerce suggest that the mean annual precipitation for
that site at 10,500 B.P. was more than twice the value of today's
annual mean of 1933 mm (Heusser, 1974; Heusser and Streeter, 1980).
The large concentration of Cyperaceae pollen at the base of Core II
would likewise support a hypothesis of increased mean precipitation.
To suggest that correlation is possible between Puerto Vancouver
and Alerce, Chile far to the north is based on the fact that both

locales today support coastal rain forests with similar climatic regimes,

65

the Alerce site being in the Valdivian rain forest and Puerto Vancouver
being in the Magellanic rain forest.

Also if our zone correlates with the time frame of 9410 -
11,300 B.P., we would expect lower sea levels than today's levels when
the Postglacial eustatic response of sea level to ice melting is
taken into account. The pollen profile for A-1 does not match that
which would be expected for littoral vegetation. For example, two

of the important littoral taxa, Colobanthus and Crassula, are not

 

represented in this zone, although they are represented elsewhere in

the core. It suggests that the shoreline was further away from the

Core II site than it is today, and makes much less plausible the idea
that the deforestation then was due to damage by salt spray. The

marine dinoflagellate evidence for this core (Figure 2) tends to fit

the hypothesis of a lower sea level because there are no dinoflagellates
represented in either zone A-1 or A-2, while they are represented further
up in the core. These dinoflagellates, which will be discussed later

in more detail, may be carried in sea spray into the peat as a result of
high wind and waves during a storm. However, the dinoflagellate evidence for
a lower sea level is not conclusive because there are other samples in
Core 11 without dinoflagellates. Nevertheless, the absence of marine
dinoflagellates in zone A-1 does indicate that storm damage was not
responsible for the deforestation.

The question should be asked, Can zone A be classified as
Lateglacial, while zone B is to be placed at the beginning of the Post-
glacial? A final answer cannot be reached until radiocarbon determina-
tions become available, but tentatively the answer is negative. This

zone possibly can be correlated with the basal portion of the La Mision

66

diagram (Markgraf, 1977), taken from a core in the Patagonian steppe
225 km northwest of the western tip of Isla de los Estados. Both cores
have high percentages of Cyperaceae near the base followed by a great

increase in Nothofagus. This basal zone is dated at 8490 t 400 and

 

9300 t 180 years B.P. by 14C; thus, it would be considered Postglacial.
Another evidence that zone A is Postglacial is that a high percentage
of the minor taxa (those having less than 2% of the total pollen count)
are non-alpine in affinity. The following taxa reported in zone A are
not found listed as regularly occurring alpine species for Tierra del
Fuego (Moore, 1975): Boopis, Chloreae, Chrysosplenium, Hebe, Jabarosa,

Littorella, Pratia, Samolus, and Triglochin. One would expect that

 

 

mostly alpine species would be represented if this were an assemblage
that arrived soon after de-glaciation of the region. The tentative
correlation of zone A with Heusser's Alerce core would perhaps place
it slightly earlier than the basal portion of the La Mision diagram.
Whichever is the case, zone A would be early in the Postglacial period.

In summary a clear understanding of zone A in Core II is
crucial because it offers the key to correlation with other Postglacial
pollen profiles, both at Isla de los Estados and at sites of higher
latitudes in the southern part of the continent. The high taxonomic
diversity and the low relative frequency for arboreal pollen offer
important clues to long-term climatic fluctuations having unique local
effects.

The upper three zones of Core 11 are generally characterized by

a substantial contribution of Nothofagus pollen. Zone 8 can be

 

described best as Magellanic rain forest probably dominated by

Nothofagus betuloides in the lowlands and along the lower slopes and

67

represented by N, antarctica probably on the upper slopes. At one

 

point (Pb9721) Cgltbg_must have flourished in the lowlands, probably
indicating very moist conditions there. It would be difficult to
distinguish edaphic factors from long-term climatic trends at this
point.

The transition from zone B to zone C is marked by the rise
of the Blechnaceae-Polypodiaceae and Gramineae and the decline of

Nothofagus. Zone C-1 may be described as a Gramineae-fern association

 

due to the fact that the ferns achieve a relative frequency of more
than 40% of the total pollen and spores. Some of these ferns are
represented by the tree fern, Blechnum, which would occupy the forests,

but others such as Gleichenia and some Polypodiaceae would occupy the

 

meadows and open slopes. Zone C-2 can be characterized as a Compositae—
fern association, although ferns are of relatively less importance than
in zone C-l. Zone C-3 is described as a Magellanic rain forest, or
more accurately as a Magellanic evergreen forest, due to the apparent

prevalence of N, betuloides over N, antarctica. This subzone is quite

 

 

similar to the subzones located at the tops of each of the major zones
in Core VI, and is known for its lack of diversity among the understory
constituents. Some of the total diversity is contributed by the

littoral elements, Crassula, Gunnera, and Senecio (which comprises a

 

portion of the Compositae) in zone C-3.

Zone 0 begins with a Magellanic evergreen forest in D-l, which
is not as dominant as the one in C-3 followed by a decline in
forestation in zones D-2 and D-3. This subzone of D-2 is of interest
because it was possibly a time when Gunnera occupied the lowlands and

Astelia the open patches in the Nothofagus forests on the slopes. An

 

68

Ericaceae—type heath association, which is almost entirely composed of
Empetrum, develops in the open places of the forest, as seen in D-1, and

much more extensively in D-3 as the Nothofagus forests decline. This

 

latter subzone is similar to the flora today at Puerto Vancouver. Field
notes accompanying the cores indicate that the isthmus is a boggy heath
dominated by Empetrum and accompanied by Marsippospermum, Astelia, and

Chiliotrichium. Of these only Marsjppospermum is not represented in

 

 

zone 0-3, apparently due to the low durability of its pollen. The

area today also has scattered individuals of Nothofggus betuloides

 

at the lower elevations and stands of N, antarctica at the higher

 

elevations, while the less prominent members of the community are
Berberis, Caltha, Drimys, Gunnera, and Myrteola. Of these latter only
Gunnera has been detected in the pollen record.

Paleoecological Interpretation for Core III
(Puerto Celular)

 

 

The vegetational history for Core III in general parallels
that of Core 11, one reason being that the two sites are only 16 km
apart and another being that they have similar terrain. Both cores have
an Astelia association of the Magellanic heath formation in zone A of each
respective core. However, the Cyperaceae association at the base of
Core II is absent from Core III, but it may be due to the possibility
that the sampling of Core III did not continue deep enough or that the
organic accumulation began at a later time. The Astelia heath in Core III
was maintained over a longer period of time than in Core II based
upon the fact that Astelia peaks are found throughout approximately
50 cm of the core.

Modern analogs can help clarify the pollen profile for zone A.

69

Herbarium notes (Michigan State University Herbarium, Isla de los
Estados collection) indicate that tussock grass (Poa flabellata) grows
today at approximately 100 m altitude on a hill overlooking Puerto

Celular, and this association is intermixed with Astelia, Caltha,

 

and Empetrum. It is possible that the maritime tussock formation is

represented in zone A. In regards to Astelia pumila,herbarium notes

 

(Michigan State University Herbarium) state the following: "Very
common, dominant plant of a dense heath, forming acres and acres of
uniform height, dense sheets on very steep (50° to 700 grade) and wet
hillsides of Mte. Celina in Puerto Celular." The altitude there is
said to be approximately 1000 ft. (300 m). Perhaps what is pictured
in zone A is an extensive growth of Astelia on the lower slopes in a

mat-like cushion heath, where normally Nothofagus would be growing.

 

There may have been periodic replacement of these Astelia heaths with

Nothofagus, followed by the reestablishment of Astelia on portions of

 

the slopes.

Herbarium notes (Michigan State University Herbarium) also shed
light on Armeria maritima which has been described as growing on a very
rocky area along the beach at the base of the sea cliffs of Puerto
Vancouver. In Puerto Celular it is possible that Armeria was a pioneer
species growing on the rocky substrate of the valley where Core III
was retrieved. The coring device struck rock at the base of the peat,
and Armeria occurs in the pollen record with several grains counted in
the lowest sample (Pb9693) of the core. More conclusive evidence that
Armeria once grew at the core site is the fact that it is ggt,
anemophilous (Moore and Yates, 1974) and that it is not likely that

stream transport would deposit its pollen at the coring site. A small

7O
hill separates the coring site from a stream emptying into the head of
Puerto Celular nearby.

Zone 8 is characterized by relative frequencies of Nothofagus

 

pollen greater than any other zone in the three cores. It is an
extensive development of the Magellanic evergreen forest, which appears

to be dominated by N, betuloides. At the base of the zone a sizable

 

influx of N, antarctica pollen seems to have occurred perhaps indicating
that the "krumholz" scrub was at a lower altitude at that time. Since
then it appears to have shifted to higher altitudes, thus raising the alti-

tude of the N, antarctica forest and making it less likely that its

 

pollen would reach the core site. The top of zone B has the development
of what may be considered as the Magellanic evergreen transitional forest
(Dudley and Crow, unpub. ms.), which is located today at the northwest

corner of the island and which consists of Nothofagus, Drimys and a

 

few plants growing on the forest floor. The pollen of the arborescent

Drimys winteri achieves the highest relative frequency for any sample

 

in the core at Pb9680. In addition the Nothofagus parasitic plant,

 

Myzodendron, reaches here a much higher relative frequency than in any
other sample, and this also accords with the suggestion of heavy
forestation. In addition only a small number of plants must have
covered the forest floor, mainly a few Compositae, Empetrum, and ferns.
Zone C appears to have a development of an Empetrum heath
which can be designated as Magellanic moorland formation and which may
be linked with similar developments in the uppermost portions of the
other two cores. Zone C is generally similar to the modern flora, the
main difference being that I have characterized it as an Empetrum

heath in contrast with the modern habitat which has been described as

71

a boggy Marsippospermum heath. The lack of durability for Juncaceae

 

pollen would account for this basic difference, although some Juncaceae
pollen is found in zone C. Field notes accompanying the core describe
the present vegetation as being composed of abundant Empetrum, some

Pernettya, and an occasional Chiliotrichium. The hillsides today contain

 

Astelia, Blechnum, Caltha, Drimys (occasionally). Myrteola, Nothofagus

 

 

betuloides, and Pernettya. N, antarctica has not been described from

 

the modern flora at that site, and it is interesting that N, antarctica

 

is absent from zone C, although it appears to be present in all the

other samples of Core III.

Paleoecological Interpretation for Core VI
(Bahia CrossTey)’

 

The longest of the three cores, Core VI, preserves the most
detailed account of the Postglacial vegetational and paleoecological
changes for Isla de los Estados. From the pollen record it is not
always possible to separate the local or edaphic factors from the
regional or paleoclimatic factors that account for the changing flora.
In fact, most changes in the pollen spectrum are due to both local
and regional factors interacting with one another in a very complex
fashion.

Local or edaphic changes in the pollen spectrum can be
detected on occasion when the relative frequency for one taxon changes
dramatically while concurrently the frequencies of most of the other
taxa do not shift dramatically. The closest example of this is in
sample Pb9768 where the Gramineae are dominant. Although Gunnera,
Compositae, and the Ericaceae-type pollen also decline somewhat, the

remaining taxa remain relatively stable. It is possible that there was

72

extensive dune formation at that time between the coring site and
Bahia Crossley, which are approximately 0.4 km apart, and that these
dunes were covered with Gramineae. According to the herbarium notes
of the Isla de los Estados collection (Michigan State University

Herbariun0,Hierochloe redolens is the "dominant grass of the sand

 

dunes" of the island, so it may have been the major constituent of the
Gramineae peak. Today the dunes extend to approximately 50 m frOm the
coring site. Another possibility is that extensive stands of tussock

grass (Poa flabellata) developed on the headlands overlooking Bahia

 

Crossley. Unfortunately it is impossible to differentiate Hierochloe

 

pollen from 392,
Another example of a more localized change in the pollen spectrum
is the influx of Astelia in sample Pb9758. Possibly there may have

developed a break in the Nothofagus forests on the slopes opening the

 

way for the growth of Astelia mats. It is also possible that extensive
wind damage, erosion, or storm activity may have developed these forest
openings. Dinoflagellate cysts reach their highest concentration of
any sample up to that point in the core, and this could be indicative
of intensive storm activity. On the other hand, that part of the world
is noted for its almost continuous storminess, so other factors could
have been involved.
The long-term paleoclimatic trends in Core VI are dominated

by four major climatic cycles which are reflected in four major cycles
of pollen sequences. The four uppermost pollen zones define the limits

of the four pollen sequences. It appears that three taxa, Nothofagus,

 

Compositae, and the Ericaceae-type are involved in the four major

pollen cycles, and these are diagramed in Figure 6. Each zone boundary

73

FIGURE 6
FOUR MAJOR VEGETATIONAL CYCLES IN CORE VI

Nothofagus Compositae Ericaceae-type

Zone E

 

Zone 0

 

Zone C

 

Zone B

 

 

(Taken from Figure 4)

74

is defined as the transition from relatively high Nothofagus percentages

 

to relatively low percentages. For the duration of each zone Nothofagus

 

gradually increases from minimum values to maximum. The transition
from maximum back to minimum values is relatively rapid when contrasted
with the gradual increase to a maximum. Zone A does not show a gradual
increase in Nothofagus because the sampling ended at its base, but it
is presumed if the sampling zone could have been extended to a lower

level it might indicate a decrease in Nothofagus values below the present

 

sample levels.
The Compositae and Ericaceae-Empetraceae cycles are out of

phase with one another and with those of Nothofagus, but the length of

 

each cycle is of approximately the same duration as the length of the

corresponding Nothofagus cycle. The peak for each Compositae cycle

 

is reached below the peak for each Nothofagus cycle. 0n the other

 

hand the peak for each Ericaceae—Empetraceae cycle, although not having
as great an amplitude, occurs above the corresponding peak of the

Nothofagus cycle. It becomes immediately clear that we can infer from

 

the pollen data of Core VI four major successional cycles. The

succession follows the order of Nothofagus, Ericaceae-Empetraceae, and

 

Compositae, this sequence being repeated at least four times during the
Postglacial period. The following table designating the zone or

subzone where each peak occurs illustrates the successional nature of

these cycles as shown in Figures 4 and 6:

 

 

 

Nothofagus Ericaceae-type Compositae
Zone A B-l B-2
B-2 C-1 C-3
C-3 D-l D-2

D-2 E-l E-2

75

The four vegetational cycles can be described in terms of the
major plant formations found on the island today. At the tops of

zones B,C, and D Nothofagus reaches a maximum development, and this

 

can be characterized as Magellanic evergreen forest. The main constituent

of this forest appears to have been N, betuloides accompanied by a

 

relatively small proportion of Drimys winteri. According to the computer

 

analysis of Nothofagus, N, antarctica maintains an amazingly consistent

 

 

pattern of relatively low percentages of total pollen, usually between

2% and 8%. This would seem to indicate that N, antarctica probably has

 

existed in its usual stands of scrub at higher elevations continuously
over a large portion of the Postglacial period. This also corresponds to
the modern vegetation summary for the habitat surrounding the core

site. N, antarctica is said to exist today on the higher slopes with

a few scattered individuals along a nearby stream. Drimys winteri

 

also has very few representatives in the valley, but it becomes more

abundant on the lower hillsides. Today some scrub N, betuloides

 

occupies the meadow and the stream side, and an abundance of this
evergreen southern beech occurs on all the surrounding slopes. It
would seem that during the maximum development of the evergreen forest,
.fl- betuloides must have spread more extensively into the meadows

surrounding the core site more so than its present destination.

The second component of the vegetational cycles, the Ericaceae-
Empetraceae, can be correlated best with the Empetrum association of
the Magellanic moorland formation. This stands in contrast to the
present-day picture because the field notes accompanying the core do
not mention the presence of Empetrum. The third and fourth cycles of
the Empetrum heath development are noted for their higher relative

76

frequencies of pollen than do the first two. The last cycle is
especially Significant in terms of the extent of heath development both
spatially and temporally. It must have been a strong dominant over the
other vegetation formations for a considerable period of time due to

its representation in more than a meter of the core. The four Ericaceae-

types, Empetrum, Gaultheria, Lebetanthus, and Pernettya, have been

 

 

 

identified in the pollen record here, and all appear to be members of

this heath, which must have occupied the meadow as well as the slopes.
The third component of the vegetational cycles, the Compositae,

achieve a peak that is usually quite dominant prior to the time when

Nothofagus reaches it maximum. In the modern flora the composites

 

Chiliotrichium diffusum and Senecio smithi are listed as being present.

 

 

It is difficult to assign this part of the cycle to any particular
vegetation formation because the composites are so numerous and diverse
in their ecological requirements that one would not want to limit them
to any one habitat. One that possibly would fit the pollen profile is

the meadow formation, which is dominated by Marsippospermum. Both

 

Chiliotrichium and Senecio are members of this formation, which is the

 

dominant formation around the core sight today.

The question can be asked, At what point does the present-day
surface intersect the climatic and vegetational cycles? Definitely
the modern vegetation does not represent the Ericaceae-Empetraceae
heath formation because Empetrum does not appear to be a member of the
modern flora. Also the highest sample in the core (Pb9733) has less

than 2% of that type of pollen. The Nothofagus forest does not seem

 

to have reached its maximum development, otherwise sample Pb9733

should have much more Nothofagus pollen than it does have. In addition,

 

77

the unforested meadow around the core site today would allow for a much

more extensive development of the Nothofagus forests. The evidence is

 

strongest that the present flora represents an intersection with the
maximum development of the Compositae portion of the cycle. As already
noted, the Compositae achieve their greatest dominance in sample Pb9733.
Unfortunately, no samples higher in the core than that are available for
analysis.

The larger question and more speculative one is this, Can we use
these inferred paleoclimatic and paleoecological cycles as a means of
prediction? It lies outside the scope of this study to answer that
question because it would depend on many contingencies, the main one
being whether the cycles are repetitive in the same order of succession.
Another is the question of the duration of the cycles, especially the
question of how variable are the lengths of the cycles.

The Compositae and Ericaceae-Empetraceae components of the
cycles usually fluctuate in an inverse relationship to one another.

This can be noted by a careful comparison of the adjacent columns for
each on the diagrams (Figures 4 and 6). The question should be raised
as to whether they are competing taxa. The Ericaceae-Empetraceae do
not always compete with the Compositae for the same ecospace, for the
maximum development of the former do not always result in the decline
of the latter. However, competition may be in the other direction,

the Compositae competing for the ecospace of the Ericaceae-Empetraceae.
It should be noted that whenever the Compositae reach their maximum
development the Ericaceae-Empetraceae decline to very low percentages,
or in the case of one sample (Pb9777) the latter disappears from the

record entirely. The competition between these two taxonomic groups

78

may help to explain in the future the nature of these paleoclimatic

cycles.

Synthesis

In making over-all comparisons between the paleoecological
interpretations of the three cores, one prominent feature is the
development of heavily dominant Empetrum heaths as indicated in the
t0p portion of all three cores. From this it can be concluded that
during a period of several centuries, or perhaps longer, Isla de los
Estados was blanketed by a major vegetational formation in the lower
elevations, that of a Magellanic heath with a dominant Ericaceae-type
association. This same phenomenon has occurred across Tierra del Fuego
as depicted on Auer's pollen diagrams for southern Patagonia (Auer,
1958). The pollen diagram from La Mision shows an Empetrum peat at
3.0 m in the 9.2 m core and the continued presence of Empetrum (Mark-
graf, 1977). However, its values are much lower than those on Isla
de los Estados, rising to just over 5% relative frequency at its
maximum. Even though the La Mision site cannot be characterized as
having an Empetrum heath due to its classification as Patagonian
steppe formation, it does indicate that conditions were more favorable
for the growth of Empetrum at the 3 m level than perhaps at any other
point in the Postglacial period. The pollen diagrams from Isla de los
Estados and other parts of Tierra del Fuego can be justifiably used to
determine certain paleoclimatic trends during the Late Quaternary.

For Isla de los Estados a climatic factor readily derived from
the pollen profiles is that of temperature. The arboreal pollen

percentages of the three cores are thought to be directly correlated

 

 

79

with temperature changes. There appears to be a cyclicity of fluctua-
tions from high to low AP percentages, which could not be explained on
any other climatic basis, such as, storm damage or precipitation

changes. As already noted previously, the arboreal pollen percentages,

which are composed basically of Nothofagus with an occasional 1% or

 

2% of Drimys, correlate well with the varying fluctuations between N,

antarctica and N, betuloides.

 

 

If the arboreal pollen percentages, which are essentially the

Nothofagus percentages, are temperature-dependent, then we should

 

expect to find a degree of correlation with the other temperature
curves for southern South America. Unfortunately most of the 00119"
diagrams for this part of the world have not been translated into
temperature curves. Auer (1974) interpreted his diagrams more in
terms of sea level fluctuations than in terms of temperature changes.
Markgraf (1977), in reinterpreting Auer's La Mision diagram on the
basis of sampling again the entire section, found in the pollen record
evidences of humidity as well as temperature changes, although her
study does not report a temperature curve. In northern South America
some of the Late Quaternary pollen diagrams have been interpreted in
terms of vegetational zones changing altitudinally, lake levels
fluctuating synchronously with zone shifts, and sea levels fluctuating,
all of which are related to temperature changes (Van der Hammen, 1974a,
1974b).

The best and most detailed temperature curve for the Late
Quaternary of southern South America has been produced by Heusser
and Streeter (1980), covering the last 16,000 years. They first

derived a set of regression equations from modern pollen rain in

80

various parts of Chile by which pollen data can be directly correlated
with mean January (summer) temperature. Then they applied these
equations to the pollen data found in a radiocarbon-dated core
obtained from the lake bottom at Alerce, Chile. The temperature
curve for the Postglacial time at Alerce, Chile, describes an over-
all pattern having similar ties with the arboreal pollen curve at
Bahia Crossley, Isla de los Estados, Argentina (Figure 7). Unfortunately,
we do not have radiocarbon dates for a more precise comparison with
the Chilean data.

In addition to the temperature curve, Heusser and Streeter
(1980) prepared a precipitation curve described as mean annual precipita-
tion for the Alerce area. With some exceptions the precipitation curve
is the inverse of the temperature curve. A comparison between the
precipitation curve of Alerce with the arboreal pollen curve at Bahia

Crossley indicates that the Nothofagus fluctuations of Isla de los

 

Estados should be viewed indeed as directly correlated with temperature,
not precipitation changes.

The Isla de los Estados temperature curve also has been
compared with the re-interpreted La Mision diagram (Markgraf, 1977;
D'Antoni, 1980). Figure 7 suggests that the two curves are not as
closely parallel to each other as the Bahia Crossley and Alerce
diagrams are. This at first appears strange in view of the fact that
the first two are separated by only about one degree latitude, while the

Bahia Crossley and Alerce sites are separated by 13° latitude. The

apparent anomaly of how two widely separated geographical areas could
have closer pollen and temperature patterns than two geographically

close sites is clarified by an examination of the present climatic

81

FIGURE 7

CMPARISON OF THE LATE WATERNARY PALEOTEMPERATURE

TRENDS IN THE HIGH LATITUDES OF THE SOUTHERN

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82

regimes in each. Alerce and Bahia Crossley are both in areas of high
precipitation and relatively moderate differences between summer and
winter mean temperatures, thus they support a rain-forest vegetation.
The main differences are that the former lies in the Valdivian rain
forest and has a higher mean temperature, and the latter is found in
the Magellanic rain forest. The precipitation for Alerce today is 1933 mm
annually (Heusser, 1974), while for Isla de los Estados it is 1701 mm
annually (Table 3). This stands in contrast with La Mision, which
today lies outside of the Magellanic rain forest and which has an
annual precipitation of less than 500 mm (Markgraf, 1977). It lies
within the vegetation province known as Patagonian steppe. It appears,

then, that the Nothofagus curve from La Mision diagram may be a

 

reflection as much of precipitation changes as of temperature. Once
the mean annual precipitation in the past exceeded 800 mm, then enough

moisture would be present for a Nothofagus forest to begin to develop.

 

When precipitation levels dropped to that of the present level,

Patagonian steppe would be the natural result. The Nothofagus curve

 

of La Mision iNOUId not be expected to closely parallel that of Isla

de los Estados.

Besides temperature data derived from the Nothofggus curve of

 

the Bahia Crossley core, it is possible to derive precipitation data.

It appears that the percentage changes in the Ericaceae-like taxa
(Empetraceae, Epacridaceae, Ericaceae) are dependent upon precipitation
changes. The dominant species in the southern oceanic wet—heathlands

is Empetrum rubrum (Moore, 1979), and the dominant Ericaceae-type pollen

in all three cores is Empetrum rubrum, the only species of Empetrum

 

in the Magellanic region. The precipitation in the heathland or

83

Magellanic moorland varies in annual values from 5000 mm on Isla
Wellington, Chile, to 600 mm on the Falkland Islands (Moore, 1979).
Although many factors, such as cloud cover, soil run-off, exposure to
prevailing winds, can be responsible for variations in heathland
composition, one major factor in the development of the heathland is
precipitation.

Besides temperature and precipitation, another important
climatic factor which has had an effect on the vegetation history of
Isla de los Estados is that of wind. As mentioned earlier, the wind is

a major factor in the formation of the Nothofagus "krumholz". Generally

 

the effects of wind would be nearly impossible to detect from an

analysis of the pollen profiles, but the three Isla de los Estados cores

offer the unusual possibility of ascertaining the wind effects by means

of marine dinoflagellates, which are found almost continuously throughout

the core samples. They are roughly in two different sizes and are

illustrated in Plate 6 (Figures 6-13, 6-14, and 6-15). The smaller

sized dinoflagellates definitely outnumber the larger ones, possibly

due to the fact that the wind would have transported the smaller ones

greater distances and due in part to smaller forms being in near shore waters.
Most likely the marine dinoflagellates have been transported to

the three core sites by means of wind rather than by flooding of the

peat deposits. There is no evidence of marine transgressions as there

is for the La Mision site to the northwest on Isla Grande (Auer, 1974;

Markgraf, 1977). As wind squalls would pick up moisture from the

ocean surface or as the wind would scatter the salt spray created from

the wave action on the rocky shore, dinoflagellates could easily have

been carried in the sea water droplets and deposited at their present

84

location inland. It is theorized that an increase in their relative
numbers may indicate an increase in storm or wind activity. All three
core sites are in sheltered areas at the end of narrow bays, so the
presence of dinoflagellates becomes all the more remarkable and attests
to the force of the wind. The isthmus between Puerto Vancouver and
Puerto Cook has the lowest relative percentages, and zones 0 and E of
Core VI at Bahia Crossley have the highest. Bahia Crossley has an
exposure only to the northwest, Puerto Celular has an exposure only

to the south or southeast, and Puerto Vancouver-Puerto Cook has an
exposure both to the north and to the south.

Ultimately it may be possible to compare the temperature profile
of Isla de los Estados with those which are being obtained from Antarctic
ice cores by means of oxygen isotope ratios (Johnsen, et_gl,, 1972;
Robin, 1977; Lorius, gt gl., 1979). With the present technology, the
ice cores cannot be dated with radiocarbon, and their ages have to be
estimated using complex methods. The only ice-core climatic record
which has been correlated with the radiocarbon time scale is the one
obtained from Dome C, which is nearly 2000 km from the South Pole in the
direction opposite to that of South America (Lorius, et_gl,, 1979).

The resulting temperature curve from Dome C can be compared with the
pollen curve from Bahia Crossley (Figure 7), but much more work needs

to be done at both sites before any cross-correlations are attempted.

It may be possible that the Antarctic oxygen isotope studies will help
to clarify the enigmas surrounding the four major paleoecological cycles
in the Bahia Crossley pollen diagram.

Future studies of the Late Quaternary palynology of Isla de

los Estados should concentrate on tying the vegetatiOn history firmly

85

with the radiocarbon time scale, converting the pollen profiles into
temperature and precipitation values, correlating surface samples and
present-day pollen rain with the pollen data, correlating variations

in aperture numbers of Nothofagus pollen from fossil samples with those

 

from living Nothofagus, determining the cause and the timing for the

 

four major paleoclimatic cycles as inferred from the Postglacial pollen
record, constructing the fluctuations of vegetation patterns throughout
the island within the larger context of vegetation changes for all of
southern South America, and testing the feasibility of correlating
paleoclimatic pattern changes between southern South America and

Antarctica.

LIST OF REFERENCES

LIST OF REFERENCES

Arroyo, S., 1975. Lebetanthus, genero austoamericano de Epacridaceae
y sus diferencias con el genero Prionotes de Tasmania.
Darwiniana, 19:312-330.

 

Auer, V., 1958. The Pleistocene of Fuego-Patagonia. Part II. The
history of the flora and vegetation. Ann. Acad. Sci. Fennicae,
Ser. A, III, 50:1-239.

, 1960. The Quaternary history of Fuego-Patagonia. Proc.
Royal Soc. London, Ser. B, 152:505-516.

 

, 1965. The Pleistocene of Fuego-Patagonia. Part IV. Bog
profiles. Ann. Acad. Sci. Fennicae, Ser. A, III, 80:1-159.

 

, 1966. Climatic variations in Fuego-Patagonia. Ig_
D. I. Blumenstock, ed., Pleistocene and Post-Pleistocene
Variations in the Pacific Area, pp. 37-55, Bishop Museum
Press, Honolulu.

 

, 1974. The isorhythmicity subsequent to the Fuego-Patagonian
and Fennoscandian ocean level transgressions and regressions

of the latest glaciation. Ann. Acad. Sci. Fennicae, Ser. A,

III, 115:1-188.

 

, Salmi, M., and Salminen, K., 1955. Pollen and spore types
of Fuego-Patagonia. Ann. Acad. Sci. Fennicae, Ser. A, III,
43:1-25.

 

Blumenstock, D. 1., ed., 1966. Pleistocene and Post-Pleistocene
Variations in the Pacific Area. Tenth Pacific Science Congress,
Honolulu, Hawaii, 1961. Bishop Museum Press, Honolulu.

Borrello, A., 1972. Cordillera Fuegina. In A. Fl. Leanza, ed.,
Geologia Regional Argentina, pp. 741L753, Acad. Nac. Ciencias,
Cordoba.

Crow, G. E., 1975. Vegetation of Isla de los Estados, Argentina.
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Dalziel, I. W. D., 1972. Structural studies in the Scotia Arc: Isla

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86

87

Dalziel, I. W. D., 1976. Structural studies in the Scotia Arc: "base-
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U. S., 11(2):75-77.

, Caminos, R., Palmer, K. F., Nullo, F., and Casanova, R.,

 

1974. South extremity of Andes: Geology of Isla de los
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, Dott, R. H., Winn, R. D., and Bruhn, R. L., 1975. Tectonic

 

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, Elliot, 0. H., Thomson, J. W., Thomson, M. R. A., Wells,

 

N. A., and Zinsmeister, W. J., 1977. Geologic studies in the
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D'Antoni, H. L., 1980. Neuvos datos para la historia vegetacional del
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Dudley, T. R., and Crow, G. E. Index to the flora of Isla de los
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The vegetation (of Isla de los Estados). Unpublished
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Erdtman, G., 1966. Pollen Morphology and Plant Taxonomy. Angiosperms.
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Hafsten, U., 1960. The Quaternary history of vegetation in the South
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Harrington, H. J., 1943. Observaciones geologicas en las Isla de los
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, 1962. Paleogeographic development of South America.
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Heusser, C. J., 1971. Pollen and Spores of Chile. 167 pp., Univ. of
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, 1974. Vegetation and climate of the southern Chilean lake
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88

Heusser, C. J., and Streeter, S. S., 1980. A temperature and precipi-
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Huang, T. C., 1972. Pollen Flora of Taiwan. National Taiwan Univ.,
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Imshaug, H. A., 1972. R/V Hero Cruise 71-5 to Isla de los Estados.
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Johnsen, S. J., Dansgaard, W., Clausen, H. B., and Langway, C. C., 1972.
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APPENDICES

(3)

(4)

(5)

(6)

(7)

(8)

APPENDIX A
PROCESSING AND MOUNTING TECHNIQUES

Place approximately 50 ml of 5% KOH in a small glass beaker and add
the peat sample.

Heat the KOH to the boiling point in a water bath and stir peat
mixture into the KOH using a glass stirring rod to break up and
disperse the peat mass. Allow the sample to boil very gently for
several minutes until the peat is completely dispersed. The KOH
solution should be dark brown.

Pour the contents of the beaker through a fine screen and collect
the filtrate and fine residue in a second beaker. Carefully wash
the residue remaining on the screen, using a wash bottle, to extract
additional fine material. Discard the coarse material remaining

on the screen.

Transfer the contents of the second beaker into 90 ml glass centri-
fuge tubes and centrifuge at 1550 RPM for 5 minutes.

Alternately wash with distilled water and centrifuge the contents

of the tube 3 times.

After the third wash in distilled water transfer the contents of the
tube into a sample vial using a smgll_amount of distilled water.
Spin down the contents of the vial using a clinical style centrifuge
for 2 minutes.

Remove excess water using the aspirator and add 3 drops of safranin
O stain. Shake the vial to mix the contents and allow to stand for

20 minutes.

91

(.9)

(10)

92

APPENDIX A (cont'd)
Fill the vial with water, mix thoroughly and centrifuge for 2
minutes. Aspirate the supernatant liquid. Repeat this process
until the supernantant liquid shows no trace of stain.
Add an amount of melted glycerin jelly appropriate to the volume
of residue; shake the vial to mix the contents, cap securely and

store.

Mounting residue on microscope slides:

(l)

(2)

(3)

(4)

(5)

Place the vial containing the residues in hot water bath until the
glycerin jelly will flow easily.

Put two drops of the residue on glass cover slip 22 mm round or
square. Use No. l or No. l% thickness glass (ll-l7 micrometers).
Center a properly labeled standard 25 x 75 mm microscope slide on

the cover slip and turn over assembled slide to an upright position.
Place the mounted sample on a warming table to cause the glycerin
jelly to spread evenly.

Seal the sample permanently by applying clear enamel (such as finger-

nail polish) around the edges of the cover slip.

Rad

110
120
130
140
150
160
170
180
190
200
210
220
230
240
250
260
270
280
290

APPENDIX B

COMPUTER PROGRAM FOR DIFFERENTIATING NOTHOFAGUS SPECIES

 

io Shack TM Level II BASIC for the TRS-80 Model 1 Microcomputer

CLS:PRINT"NOTHOFAGUS IDENTIFICATION PROGRAM"
PRINT"ISLA DE LOS ESTADOS POLLEN STUDY"
PRINT

INPUT"SAMPLE NUMBER";S$

INPUT"TOTAL POLLEN";TP

INPUT"TOTAL NOTHOFAGUS";TN

INPUT"TOTAL 7 PORED NOTHOFAGUS";T7
INPUT"TOTAL 5 PORED NOTHOFAGUS";TS
CLS

LPRINT".":LPRINT".":LPRINT”SAMPLE: ";S$
A7=.47

A5=.03

B5=.67

TA=T7/A7:TA=INT(TA)

T5=T5-(T5*A5)

TB=T5/B5:TB=INT(TB)

IF (TA+TB)>TN THEN TB=TN~TAzTX=OzGOT0200
IF (TA+TB)=TN THEN TX=O:GOT0200
TX=TN-(TA+TB)
LPRINT"TAXON","TOTAL","PERCENT"
LPRINT"N. ANTARCTICA",TA,(TA/TP)*IOO
LPRINT"N. BETULOIDES",TB,(TB/TP)*IOO
LPRINT"UNK. NOTHOFAGUS",TX,(TX/TP)*100
LPRINT"ALL NOTHOFAGUS",TN,(TN/TP)*1OO
CLS

INPUT"ANOTHER SAMPLE (Y/N)";R$

IF R$="Y" THEN CLS:GOTO 40

IF R$="N" THEN END

CLS:GOTO 260

93

APPENDIX C
NOTHOFAGUS APERTURE COUNT--CORE II

 

 

 

 

 

Sagble Number of apertures: Total Total
Numger 4 5 6 7 8 Nothofagus Pollen
9694 10 10 20 100
9695 3 25 23 51 200
9696 9 2 1 12 100
9698 58 6O 7 125 200
9699 2 28 16 1 47 90
9700 15 15 1 31 100
9701 5 33 28 1 67 200
9702 2 23 14 39 100
9705 3 55 37 3 98 200
9706 1 48 34 83 100
9707 76 74 3 153 200
9708 1 28 31 1 61 100
9709 1 26 15 1 43 200
9710 2 14 13 29 100
9711 18 26 1 45 100
9712 1 24 23 1 49 200
9715 2a 46 54 4 106 200
9716 24 28 1 53 100
9717 2 17 12 1 1 33 100
9718 7 6O 61 7 135 200
9719 1 29 43 73 100

 

aIncludes one Nothofagus grain with three apertures.

94

 

95

APPENDIX C (cont'd)

 

 

 

Nfifiglg 4 Numzer °fzpert"r:s‘ 8 Nolfigfggus PSIIln
9720 1 24 57 1 83 100
9721 5 7o 87 18 3b 183 300
9722 19 37 2 58 100
9723 2 15 1 44 100
9724 3 1 4 200
9725 3 3 150
9726 3 3 6 100
9727 1 1 2 150
9728 1 1 2 84
9731 o 250

 

bIncludes one grain with nine apertures.

APPENDIX D
NOTHOFAGUS APERTURE COUNT--CORE III

 

 

 

 

 

Saggle Number ofggpertures: Total Total
Number 4 5 6 7 8 Nothofagus Pollen
9676 1 10 7 18 182
9680 4 106 66 2 178 250
9681 48 4O 2 90 100
9683 150 172 6 278 300
9685 41 25 13 79 200
9687 49 122 11 182 200
9688 7 7 14 200
9691 6 10 1 17 200
9693 3 3 1 7 200

96

APPENDIX E
NOTHOFAGUS APERTURE COUNT--CORE VI

 

 

 

 

135E: 4 °‘° 8 $2112..
9733 9 14 2 3 28 150
9736 1 9 11 1 22 124
9737 2 25 26 2 1 56 142
9740 1 12 9 I 1 23 150
9741 14 22 3 1 40 200
9742 17 11 3 31 188
9744 1 18 16 3 1 39 600
9745 6 12 5 23 200
9747 3 15 14 4 2 38 150
9748 1 27 18 2 6 54 200
9749 22 12 34 200
9750 3 45 17 3 68 250
9751 1 20 11 3 35 200
9752 4 38 34 2 1 79 200
9753 2 51 54 3 5 115 200
9754 2 13 22 3 40 150
9755 1 35 19 1 56 100
9756 5 78 90 9 2C 5 189 400

 

aUN refers to unknown Nothofagus, i.e. Nothofagus whose precise
aperture count is unavailable.

b

 

 

TN refers to total Nothofagus, including the UN count.

 

cIncludes one grain with nine apertures.

97

98

APPENDIX E (cont'd)

 

 

 

Pb
Sample Number of apertures: Total
Number 4 5 6 7 8 UNa TNb Pollen
9757 46 41 5 2 94 200
9758 1 39 25 3 68 200
9759 1 12 27 9 3 52 300
9760 3 11 10 3 27 300
9761 3 48 39 2 3 95 400
9762 5 67 76 8 7 163 600
9763 6 123 93 4 4 230 400
9764 7 97 69 5 4 182 300
9765 3 22 15 1 2 43 200
9766 46 43 4 7 100 200
9767 1 36 26 6 7 76 300
9768 1 45 26 1 5 78 200
9769 9 92 63 13 15 192 400
9770 2 3o 36 6 3 77 200
9771 26 49 6 14 95 300
9772 2 36 29 4 5 76 200
9773 3 36 27 3 1 5 75 200
9774 2 17 21 6 2 48 200
9775 2 54 38 5 33 132 200
9776 3 31 42 3 18 97 200
9777 13 1o 2 2 27 200
9778 1 59 47 5 1 17 130 200
9779 2 62 68 9 141 300

APPENDIX E (cont'd)

99

 

 

 

Saggle Number of apertures: Total
Number 4 5 6 7 8 UNa TNb Pollen
9780 4 128 143 10 3 50 338 500
9781 . 1 43 49 6 2 101 200
9782 3 102 71 11 5 192 800
9783 2 57 7O 7 3 139 400
9784 4 56 77 8 1 8 154 1300
9785 1 43 82 10 2 12 150 600
9786 14 2 16 700
9787 4 56 51 3 6 120 500
9788 43 84 10 19 156 300
9789 2 68 45 8 19 142 200
9790 ___1_ __8_7_ ___75 __3 _ __1_1_ __1_7_7_ 300

TOTAL 106 2199 2081 221 10 336 4953

PLATES

100

 

 

 

 

 

 

 

 

PLATE 1
Figure Coordinates
PTERIDOPHYTA
l Aspidiaceae: Polystichum sp. Pb9726 V+7.7 X H+lO.6
2 Gleicheniaceae: Gleichenia sp. Pb9699 V-4.9 X H+20.4
3 Hymenophyllaceae: Hymenophyllum sp. Pb9762 V+6.9 X H+l9.2
4 Hymenophyllaceae: Hymenophyllum sp. Pb9719 V+2.4 X H+l5.4
5 Lycopodiaceae: Lycopodium magellanicum Pb9730 V+2.l X H+ll.5
6 Lycopodiaceae: Lycopodium magellanicum Pb9730 V+2.l X H+ll.5
7 Lycopodiaceae: LycopodiUm fuegianum Pb969l V-4.8 X H+20.0
8 Lycopodiaceae: Lycopodium fuegianum Pb969l V-4.8 X H+20.0
9 Lycopodiaceae: Lycopodium sp. Pb97l5 V-4.5 X H+23.l
l0 Ophioglossaceae: Botrychium sp. Pb9784 V-9.7 X H+23.l
ll Polypodiaceae Pb97ll V+4.9 X H+7.0
l2 Polypodiaceae Pb9739 V+5.8 X H+5.0
l3 Polypodiaceae: Blechnum sp. Pb9724 V-9.4 X H+23.8
l4 Polypodiaceae: Blechnum sp. Pb969l V-5.8 X H+27.8
l5 Podocarpaceae: Podocar us sp. Pb9685 V-6.3 X H+24.4
l6 Ephedraceae: Epfiedra sp. Pb9757 V-2.9 X H+l7.3
l7 Alstroemeriaceae: cf. Alstroemeria Pb9693 V-8.9 X H+22.3
haemantha

All illustrations lOOOX. Coordinates given in terms of mm of horizontal
(H) or vertical (V) movement in an upward (+) or downward (-) direction
from reference point.

101

PLATE

 

0L

 

102

PLATE 2

Figure Coordinates

ANGIOSPERMAE, MONOCOTYLEDONAE

 

 

 

 

 

 

 

 

 

 

 

l Centrolepidaceae: Gaimardia australis Pb973l V-6.5 X H+5.6
2 Centrolepidaceae: Gaimardia australis Pb973l V-6.5 X H+5.6
3 Cyperaceae: cf. Carex sp. Pb9753 V-l.4 X H+ll.3
4 Cyperaceae: cf. Cyperus sp. Pb969l V+7.4 X H+l4.2
5 Cyperaceae: cf. Scirpus sp. Pb977l V-6.7 X H+22.3
6 Cyperaceae: cf. Uncinia sp. Pb973l V-5.6 X H+7.l
7 Gramineae Pb9693 V+6.2 X H+ll.l
8 Gramineae Pb972l V+4.8 X H+16.2
9 Gramineae Pb977l V+O.6 X H+4.8
l0 Iridaceae: Tapeinia sp. Pb973l V+4.3 X H+l6.l
ll Juncaceae: Marsippospermum sp. Pb9731 V+4.7 X H+lB.4
12 Juncaceae: Patosia sp. Pb969l V-2.l X H+27.l
l3 Juncaginaceae: Tetroncium magellanicum Pb9709 V-5.9 X H+ll.3
l4 Juncaginaceae: Tri lochin sp. Pb9685 V-4.5 X H+l0.3
lS Liliaceae: Astelia gumila P6969l V+O.9 X H+22.3
l6 Liliaceae: Astelia gumila Pb9724 V+2.2 X H+19.7
l7 Orchidaceae: cf. Chloraea magellanica Pb9731 V+4.6 X H+l4.l
ANGIOSPERMAE, DICOTYLEDONAE
l8 Callitrichaceae: Callitriche sp. Pb9685 V+ll.0 X H+l8.7
l9 Calyceraceae: Boopi , cf. 8, gracilis Pb973l V+4.7 X H+l5.9
20 Caryophyllaceae: Colobanthus sp. Pb9727 V-6.6 X H+24.4
21 Caryophyllaceae: Cerastium sp. Pb9737 V-5.4 X H+7.7
22 Caryophyllaceae: Cerastium sp. Pb9737 V-5.4 X H+7.7
23 Caryophyllaceae: Spergularia marina Pb9730 V-l.l X H+2l.5
24 Celastraceae: Maytenus disticha Pb9755 V-6.I X H+12.4
25 Celastraceae: ngtenus disticha Pb9755 V-6.l X H+l2.4

 

All illustrations lOOOX. Coordinates given in terms of mm of horizontal
(H) or vertical (V) movement in an upward (+) or downward (-) direction
from reference point.

103

PLATE 2

 

Figure

C‘U‘l-DQJNH

All illustrations lOOOX.

104

PLATE 3

ANGIOSPERMAE, DICOTYLEDONAE

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Chenopodiaceae: cf. Suaeda sp.
Chenopodiaceae: cf. Suaeda sp.
Compositae: cf. Adenocaulon sp.
Compositae: Ambrosia sp.
Compositae: Ambrosia sp.
Compositae: cf. Baccharis sp. or
Gutierrezia sp.
Compositae: cf. Chiliotrichium sp.
or Cotula sp.
Compositae: cf. Chiliotrichium sp.
or Cotula sp.
Compositae: cf. Hypochoeris sp.
or Senecio sp.
Compositae: Mutisia sp.
Compositae: Nassauvia sp.
Compositae: Nassauvia sp.
Compositae: Nassauvia sp.
Compositae
Compositae
Compositae
Crassulaceae: Crassula moschata
Crassulaceae: Crassula moschata
Cruciferae: Cardamine sp.
Cruciferae: Draba magellanica
Cruciferae: Draba magellanica
Droseraceae: Drosera uniflora
Empetraceae: Empetrum rubrum
Empetraceae: Empetrum rubrum
Empetraceae: cf. Empetrum rubrum
Ericaceae: Gaultheria antarctica
Epacridaceae: Lebetanthus myrsinites
Ericaceae: Pernettxa sp.
Escalloniaceae: Escallonia sp.

Pb9755
Pb9755
Pb9749
Pb9690
Pb969O
Pb9706

Pb9765
Pb9765
Pb9785

Pb9721
Pb9724
Pb9786
Pb9786
Pb973l
Pb973l
Pb9733
Pb97ll
Pb9695
Pb9767
Pb9700
Pb97OO
Pb9721
Pb9784
Pb9695
Pb9730
Pb977l
Pb9691
Pb9737
Pb9751

Coordinates
V+l.l X H+7.5
V+l.l X H+7.5
V+4.l X H+8.9
V+8.5 x H+ll.2
V+8.5 X H+ll.2
V-7.9 X H+21.4
V+l.7 X H+9.2
V+l.7 X H+9.2
V-2.5 X H+20.3
V-7.2 X H+26.2
V-6.6 X H+l4.3
V-3.l X H+l7.3
V-3.l X H+l7.3
V+6.0 X H+9.l
V+6.0 X H+9.l
V-2.7 X H+8.5
V-l0.l X H+13.0
V+7.5 X H+2l.4
V+5.l X H+23.2
V+7.8 X H+21.4
V+7.8 X H+2l.4
V-6.l X H+9.9
V-3.4 X H+7.l
V+4.0 X H+23.7
V-9.0 X H+l8.3
V+7.6 X H+3.8
V-6.5 X H+l3.0
V-5.6 X H+6.l
V-7.7 X H+27.0

Coordinates given in terms of mm of

horizontal

(H) or vertical (V) movement in an upward (+) or downward (-) direction
from reference point.

105

PLATE 3

 

106

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

PLATE 4
Figure
ANGIOSPERMAE, DICOTYLEDONAE
l Euphorbiaceae: Euphorbia
cf. E, portulacoides
2 Fagaceae: Nothofaggs betuloides
3 Fagaceae: Nothofagus antarctica
4 Fagaceae: Nothofagus obliqua
5 Fagaceae: Nothofagus pumilio
6 Gunneraceae: cf. Gunnera lobata
7 Gunneraceae: Gunnera magellanica
8 Gunneraceae: Gunnera magellanica
9 Gunneraceae: Gunnera mggellanica
l0 Gunneraceae: Gunnera magellanica
ll Gunneraceae: Gunnera magellanica
l2 Haloragaceae: Nyriophyllum
cf. N, elatinoides
l3 Leguminosae: Adesmia sp.
l4 Lentibulariaceae: Pinguicula
antarctica
l5 Plumbaginaceae: Armeria maritima
(750X)°
l6 Plumbaginaceae: Armeria maritima
(75OX)

Pb97l7

Pb9719
Pb9724
Pb9719
Pb969l
Pb9762
Pb9786
Pb969l
Pb969l
Pb9786
Pb9721
Pb9693

Pb9694
Pb9761

Pb9693
Pb9693

Coordinates
V-6.9 X H+25.3
V+2.3 X H+l3.l
V+l.5 X H+6.7
V+3.3 X H+15.4
V-2.0 X H+l7.8
V-0.2 X H+l0.5
V-l.4 X H+2l.8
V-2.5 X H+9.8
V-2.5 X H+9.8
V-3.3 X H+l4.4
V+0.l X H+23.9
V+6.l X H+27.8
V+5.7 X H+22.l
V-6.2 X H+lS.4
V+3.l X H+26.0
V+3.l X H+26.0

All illustrations are lOOO magnification, except for Figures l5 and l6

which are 750 magnification.

Coordinates given in terms of mm of hori-

zontal (H) or vertical (V) movement in an upward (+) or downward (-)

direction from reference point.

107

PLATE 4

 

 

Figure

homNCDU‘I-hOON—J

3T

32
33
34

108

PLATE 5

ANGIOSPERMAE, DICOTYLEDONAE

Lobeliaceae: Pratia repens
Myrtaceae: Myrteola nummu aria
Myrtaceae: Myrteola nummularia

Myrtaceae: cf. Amomyrtus sp.
Myzodendronaceae: Myzo endron sp.
Plantaginaceae: Littorella australis

 

 

 

 

Plantaginaceae: Planta 0 sp.
Polygonaceae: Koenigia islandica
Primulaceae: Samolus spathulatus
Ranunculaceae: Caltha sp.
Ranunculaceae: Caltha sp.
Ranunculaceae: Hamadryas sp.
Rosaceae: Acaena sp.
Rosaceae: Acaena sp.
Rubiaceae: Nertera depressa
Rubiaceae: Nertera gepressa
Saxifragaceae: Chrysosplenium
macranthum
Saxifragaceae: Chrysosplenium
macranthum
Saxifragaceae: Chrysosplenium
macranthum
Saxifragaceae: Ribes magellanicum
Scrophulariaceae: Calceolaria sp.
Scrophulariaceae: Hebe elliptica
Solanaceae: Jabarosa sp.,
cf. 9, magellanica
Thymelaeaceae: Drapetes muscosa
Thymelaeaceae: Drapetes muscosa
Umbelliferae: Azorella sp.
Umbelliferae: Azorella sp.
Valerianaceae: Valeriana sp.,
cf. N, carnosa
Violaceae: Viola sp.
Winteraceae: Drimys winteri

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

UNKNOWNS

Unknown A, cf. Calceolaria or
Weinmannia

Unknown 8, cf. Tropaeoieum

Unknown C

Unknown 0, cf. Asclegjadaceae

 

 

 

All illustrations lOOOX.

Coordinates
Pb9724 H+12.5
Pb9724 H+5.5
Pb9724 H+19.3
Pb9699 H+19.0
Pb9788 H+l3.4
Pb973l H+13.0
Pb973l H+5.5
Pb9688 H+8 5

Pb976l
Pb97ZI
Pb9722
Pb9779
Pb9786
Pb9692
Pb9740
Pb9740
Pb9692

Pb973l
Pb9731

Pb9727
Pb974l
Pb9786
Pb9724

Pb9712
Pb9712
Pb973l
Pb973l
Pb9738

Pb9698
Pb968l

Pb9692

Pb9685
Pb969l
Pb9767

Humour: Chub \1 \1' .bcnmwo-bwhmootoowbw—uo
><>< ><><><><>< ><><><>< x x ><><><><><><><><><><><><><><><><><

woo

01-901 (D
><><>< ><

H+25.l
H+26.0
H+l4.3
H+l4.0
H+23.7
H+l7.3
H+9.3

H+9.3

H+l8.7

H+l7.7
H+l7.7

H+l8.6
H+7.3

H+l6.2
H+ll.4

H+20.8
H+20.8
H+8.9

H+l2.4
H+l0.5

H+5.0
H+l4.l

H+l8.5

H+lO.7
H+l4.3
H+24.5

 

 

109

PLATE 5

I

16' inwg‘u
f. . , xx
. ’ .

110

PLATE 6
Figure Coordinates

MISCELLANEOUS AND UNKNOWNS

 

 

l Unknown E, cf. Araucaria Pb9729 V+6.2 X H+25.l
2 Unknown F Pb9780 V-7.3 X H+8.8

3 Unknown G P09690 V-3.l X H+l7.8
4 Unknown H, cf. Cupressus semgervirens Pb9730 V+6.2 X H+10.9
5 Unknown I Pb9745 V-4.7 X H+21.3
6 Unknown J, cf. Cyperaceae Pb973l V+7.3 X H+l3.4
7 Unknown K Pb9691 V-2.0 X H+17.5
8 Unknown K P09691 V-2.0 X H+l7.5
9 Unknown L Pb9749 V-l.7 X H+18.0
10 Unknown M, cf. Higpuris vulgaris Pb9692 V+l.6 X H+l7.6
11 Unknown N Pb9691 V+l.9 X H+8.7
12 Sphagnaceae, S ha num sp. Pb9786 V-9.4 X H+10.7
13 Marine dinoflageliate Pb9692 V-4.9 X H+l4.9
14 Marine dinoflagellate Pb9691 V-3.3 X H+19.0
15 Marine dinoflagellate Pb9685 V-l.7 X H+27.l
16 Hepaticales Pb9770 V-l.9 X H+8.2

All illustrations lOOOX. Coordinates given in terms of mm of horizontal
(H) or vertical (V) movement in an upward (+) or downward (-) direction
from reference point.

111

PLATE 6