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UNIVERSITY OF ILLINOIS LIBRARY AT URBANA-CHAMPAIGN

L161 — 0-1096

CARNEGIE INSTITUTION OF WASHINGTON

Publication No. 381

UNIVtni.

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1 .3

1927

PRESS OF J. B. LIPPINCOTT COMPANY
PHILADELPHIA, PA.

A GEOLOGICAL COMPARISON OF SOUTH
AMERICA WITH SOUTH AFRICA

ALEX. L. DU TOIT, D.Sc., F.G.S.

WITH A PALAEONTOLOGICAL CONTRIBUTION

F. R. COWPER REED, M.A., Sc.D., F.G.S.

Published by the Carnegie Institution of Washington

Washington, 1927

- .

CONTENTS

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PAGE

Chapter I. Introduction . i

Chapter II. Geological Framework of the South Atlantic . 6

Section A. The western side of Africa . 6

Section B. The Falkland Islands . n

Section C. South America . 13

Section D. Generalized comparisons between the two continents. 1 5

Chapter III. Argentina and Bolivia . 18

Section E. The sierras of the District of Buenos Aires . 18

Section F. The southern pre-cordilleran region . 27

Section G. The pre-andine belt of northern Argentina and of

Bolivia . 55

Chapter IV. Pre-Gondwana Basement of Eastern South America . 59

Section H. The Devonian system . 59

Section I. The Early Palaeozoic beds . 62

Section J. The pre-Cambrian formations . 64

Chapter V. Gondwana System in Brazil, Uruguay, and Paraguay . 66

Section K. The Parana Basin . 66

Section L. The northeastern region of Brazil . 94

Section M. Eastern Brazil . 95

Section N. The Cretaceous of the interior . 96

Chapter VI. Geological History of the Afro-American Land-mass . 97

Chapter VII. Bearing on the Displacement Hypothesis . 109

Chapter VIII. Conclusion . 118

Bibliography . 121

Appendix. Upper Carboniferous Fossils from Argentina . 129

Triassic Fossils from Rio Claro, Parana, Brazil . 150

Index . 151

ILLUSTRATIONS

Plates I to XVI follow page 158

Geological map of part of South America . In pocket at end of volume

TEXT-FIGURES PAGE

1. Succession on the northeastern side of the Sierra de la Ventana . 20

2. Geological sketch-map of a small area along eastern base of the Sierra Chica de

Zonda to the south of San Juan . 29

3. Section, about 75 meters in height, in ravine north of the Rio Grande, Sierra

Chica de Zonda . 30

4. An infolded patch of tillite in Palasozoic beds close to Leoncito Encima, Barreal 33

5. General succession at Potrerillos . 49

6. Section, 10 km. in length through Taquara, Rio Grande do Sul, showing the

Triassic volcanics resting on an undulating surface of the false-bedded Rio do
Rasto sandstones . 91

7. Suggested continental restoration under the Displacement Hypothesis . 116

A GEOLOGICAL COMPARISON OF SOUTH AMERICA

WITH SOUTH AFRICA

Alex. L. Du Toit, D. Sc., F. G. S.

With twelve plates, one map, and seven text-figures

■

CHAPTER I

INTRODUCTION

With the passing of time and the growth of knowledge there has
come about a fuller realization of the extremely prominent part
played by the ancient continent of ‘ ‘ Gondwanaland ” in the past
history of this earth. It does not detract from its importance that
owing to lack of data the limits set to the land-masses during the
various epochs are not always properly known, or, more correctly,
the limits as seen in the relics preserved in the existing continental
masses of the globe.

We are, on the other hand, still forced to speculate as to how these
various sections, as we now find them, were bound together at the
beginning of the Mesozoic and how they ultimately came to be
parted by thousands of kilometers of ocean.

During the early part of the century and with the limited
knowledge available, it sufficed to assume that the fragments, as
we see them in South America, Africa, Madagascar, India, Australia,
and Antarctica, were linked together at some periods in the late
Palaeozoic and in the Mesozoic by equally extensive land connections,
or else by relatively narrow “land bridges,” which at later stages
became submerged by the ocean. Geological and geophysical
researches within the past decade have, however, rather severely
shaken our confidence in such orthodox views, which until then had
commended themselves by their very simplicity. Astonishing simi¬
larities — stratigraphical, lithological, and palaeontological — between
regions now parted by ocean came to obtrude themselves, becoming
all the more striking in that the fossil remains contained in these
formations were not marine, but entirely terrestrial. Almost identical
climatic vicissitudes and sequences could be deduced for the several
sections — glacial to start with and arid toward the close — though
impossible to explain under current theories, followed by volcanicity
on a truly enormous scale. Major tectonic structures found their
homologues across the wide intervening seas. Furthermore, the
marine Tertiary deposits fringing the present continental masses not
only indicated how different must have been the distribution of land
and water during that late era, but hinted at an unexpectedly recent
date for the origin of the existing oceanic basins.

The hypothesis of “continental disruption” or the “displace¬
ment hypothesis, ” brought forward independently by F. B. Taylor1
and A. Wegener,2 that the present continents have owed their posi-

1 Taylor (1910).

2Wegener (1912).

2 GEOLOGICAL COMPARISON OF SOUTH AMERICA WITH SOUTH AFRICA

tions in great part to the breaking-up of much larger land-masses in
the Cretaceo-Tertiary through the “drifting apart” of the crustal
fragments, has on the contrary helped to bring numerous other
irreconcilable facts into harmony and would almost seem to have
provided us with the key to the riddle of the structure of the earth
and more particularly of the history of “Gondwanaland. ”

In 1916, 3 though in ignorance of the details of Wegener’s doctrine,
the writer put forward an hypothesis somewhat different from those
of Taylor and Wegener, the outcome of the study mainly of the
glacial deposits of the Karroo system, supplemented by a personal
acquaintance with their Australian equivalents. Later developments
having seemingly rendered these ideas more and more worthy of
serious consideration, it became one of his aims to visit South Amer¬
ica in the hopes of being able, while gathering information about the
Gondwana deposits of that continent, to discover any evidence
favorable or adverse to the “displacement hypothesis. ”

Following the sympathetic representation by Dr. Fred. E.
Wright, of the Geophysical Laboratory of the Carnegie Institution
of Washington, and Dr. Reginald A. Daly, of Harvard University,
the president (Dr. John C. Merriam) and trustees of the Carnegie
Institution of Washington, appreciative of the scientific importance
of such a mission, most generously offered a grant in aid, and, making
use of my six months of leave from official duties, fortunately then
available, I was enabled to cross the Atlantic and spend five months
in Brazil, Uruguay, and Argentina. To the Carnegie Institution of
Washington, in thus promoting research in the Southern Hemisphere,
I am accordingly under the deepest of obligations, while I have fur¬
ther to thank them also for their generosity in publishing the results
of these investigations, rather unfortunately delayed by reason of
pressing official and other duties.

Taking into account the enormous size of the region traversed
and the time necessarily consumed in traveling, the opportunities
for original investigation were naturally limited, and it was often
with keen regret that a particular line of research had to be dropped
just as it was disclosing results of consequence. Nevertheless, the
knowledge so acquired has permitted the copious scattered literature
to be read with a certain amount of discrimination and has enabled a
closer comparison of the Gondwana system of South America to be
made with that of South Africa than has hitherto been possible.
Papers in the English language on the geology of any part of South
America are relatively few, while those in Spanish or Portuguese
dealing comprehensively with any one of its republics are equally
rare. Consequently, instead of limiting this account to the points
investigated personally, the opportunity has been taken, although at

* Du Toit (1916).

INTRODUCTION

the risk of undue length, of reviewing in addition the geology of
South America in so far as it may have a bearing on the problem of
Gondwanaland and of a former connection between Africa and the
New World. The extraordinarily divergent conclusions reached on
many vital questions by various eminent South American geologists
is eloquent proof indeed as to the need of such a summary for
the benefit of English-speaking persons. Furthermore, the notable
advances made in recent years have rather impaired the value of that
monumental work by Suess, The Face of the Earth, which even the
French edition with its new maps and copious references to recent
literature just fails to restore.

In this, the first comprehensive summary of the geology of the
eastern part of South America, considerable liberty has been taken
in the interpretation of the accounts of areas which naturally could
not be visited, and doubtless there will be found not a few statements
or conclusions to which the local geologists can and will take excep¬
tion. It is nevertheless hoped that such differences in the presenta¬
tion and interpretation may not be of too violent a character; for
such the insufficiency of the data, even for the better known parts
of this enormous territory, must in part be held responsible. Con¬
siderable difficulty was experienced in the preparation of the accom¬
panying geological map ; drastic alterations are required to Branner’s
map of Brazil,4 while that by Leme,5 though more up to date, is on a
smaller scale and not sufficiently detailed; Walther’s map of Uru¬
guay 6 is valuable, but there is no general map of Argentina, while
much of Paraguay, Bolivia, and the adjacent part of Brazil are
geologically unexplored.

I found my South American confreres keenly interested in the
problems herein discussed, though the size of their countries, the
smallness of the staffs, the pressure of economic work, and the lack of
coordinated effort between the geological surveys of the various
republics and states have hindered the carrying out of any compre¬
hensive scheme of work thereon. Furthermore, no one had any
first-hand acquaintance with any of the other countries possessing
Gondwana beds. I have reason to believe that interest in these
problems has been appreciably stimulated as the consequence of
this visit. While immediate results therefrom could hardly be
expected, attention might be drawn to a paper by Professor
Walther7 on the Borings for Coal in Cerro Largo, Uruguay, and
one by Senor E. T. Arocena8 on the Glacials in the Department of
Durazno as the outcome of certain observations made by the writer
in that republic.

In order to aid comparisons with the African continent, a brief

4Branner (1919). 6 Walther (1919). 8Arocena (1926).

6 Leme (1924). 7 Walther (1924).

4 GEOLOGICAL COMPARISON OF SOUTH AMERICA WITH SOUTH AFRICA

account is given of the geological features of its western side, the
literature thereon being rather scattered, with much uncertainty
pertaining to the territories from Angola northward, while a sum¬
mary of the geology of the important Falkland Islands has also been
introduced for reasons that will appear in the sequel.

The schematic representation embodied in Figure 7 will assuredly
be subjected to active and probably to hostile criticism on the score
of the fantastic and apparently improbable character of the dis¬
placement theory, but a close and impartial study thereof is invited,
so that the numerous congruences and '‘coincidences” in the stra¬
tigraphy, structure, etc., of the two great land-masses now parted
by the South Atlantic may be duly scrutinized and pondered over,
the weaknesses of the arguments advanced duly pointed out, and
more reasonable alternatives suggested in explanation of the facts or
their interpretation.

Leaving Cape Town on June 12, 1923, Rio de Janeiro was reached
a fortnight later, where the director of the Geological Service,
Dr. Euzebio Paulo de Oliveira, with the permission of the Brazilian
government, kindly detailed Dr. L. F. Moraes Rego to act as my
guide and instructor, under whose able direction a tour was made of
nearly six weeks’ duration, the department obligingly providing
rail transport. The program embraced a short visit to Ouro Preto,
Bello Horizonte, and Diamantina to inspect the ancient formations
of Minas and the Boa Vista Diamond “pipe.” The journey from
Sao Paulo to Ityrapina and Bauru provided sections of the Triassic
“traps” and the Cretaceous of the interior, while a trip through
Ponta Grossa, Iraty, Roxo Roiz, Marechal Mallet, Rio Claro, Porto
Uniao, and Rio Negro to Curityba enabled the Devonian as well as
the full succession of the.Gondwana system to be studied. Taking
the steamer from Paranagua to Porto Alegre, Taquara, Cachoeira,
Ferreira, Santa Maria, and Sant’ Anna were visited, enabling good
sections of the Triassic sediments and volcanics to be inspected.

In Uruguay the director of the Section of Geology and Water
Boring, Senor E. Terra Arocena, generously placed his records at my
disposal, while Dr. Karl Walther, professor of Geology at the Insti¬
tute of Agronomy, Montevideo, kindly supplied me with valuable
information. Fraile Muerto provided confirmation of the existence
of Carboniferous glacial beds, originally reported therefrom by
Guillemain, while Melo, Paso del Cerro, Santa Rosa, and Sauce were
also visited.

In Buenos Aires, through the courtesy of the Minister for Mines,
the director of the Geological Survey, Dr. J. M. Sobral, whole¬
heartedly detailed several of his staff to accompany me in turn on a

INTRODUCTION

tour of nearly two months, namely, Dr. Franco Pastore, Dr. Augusto
Tapia, and Dr. Juan J. Nagera, the government defraying the cost
of rail transport. The route lay through Villa Dolores, Bajo de Velis,
Cordoba, La Cumbre, Capilla del Monte, Marayes, San Juan, Men¬
doza, Cacheuta, Uspallata, Barreal, and across the Andes to Val¬
paraiso in Chile and back to Buenos Aires ; this enabled the various
horizons in the Gondwana system to be inspected. Trips were made
to Olavarria, Sierra de la Ventana, and La Plata to study the equiva¬
lents of the “Cape Fold ranges. ”

The return journey was made by Montevideo, Santos, Sao Paulo,
Rio de Janeiro, and Pernambuco. Through the kindness of Dr.
Miguel A. de Lisboa, director of Irrigation, a rapid journey was
made by rail to Campina Grande and thence to the irrigation dams
under construction at Gargaleira and Parelhas in Rio Grande do
Norte, every facility being placed at my disposal by the Brazilian
government through the agency of Doctor Netto. The voyage there¬
after was made via|Madeira| arriving at Cape Town on December
io, 1923.

Among the numerous other persons to whom I have been particu¬
larly indebted are Drs. T. H. Lee, Paulino F. de Carvalho, and
Axel Lofgren, of the Brazilian Geological Service, Dr. Joviano A.
Pacheco, head of the Geographical and Geological Commission
of the State of Sao Paulo, Drs. Pablo Groeber, Roberto Beder, Juan
Rassmuss, Anselmo Windhausen, Ricardo Wichmann, and Hausen,
of the Geological Survey of Argentina, Dr. Juan Keidel, formerly
director of that survey, Dr. H. Schiller, of the Museum of La Plata,
Dr. C. Hosseus, of the University of Cordoba, and Mr. H. J. Hawley,
geologist to the Standard Oil Company. To my former South African
friends, Mr. Bernard W. Ritso, M.I.C.E., late director of the Section
of Water Boring in Uruguay, Mr. David Draper, F.G.S., manager of
the Boa Vista Diamond Mine, to Mr. F. W. Scott, M.I.C.E., engi-
neer-in-charge at Gargaleira, and Mr. B. H. Heatlie, of Buenos Aires,
I am under great obligations. Furthermore, to Mr. L. S. Goldsmith,
of the Geological Survey, Pretoria, is due the lettering on the Geo¬
logical map.

My thanks are due to Dr. R. S. Bassler, of the United States
National Museum, Washington, for his opinion on the invertebrate
fossils collected in Brazil and Argentina, whilst, finally, I am exces¬
sively indebted to my friend Dr. F. R. Cowper Reed, of the Sedgwick
Museum, Cambridge, England, for his labors on these collections,
the results of which are embodied in the valuable Appendix to this
report. His noteworthy discovery of the Triassic affinities of the
Estrada Nova mollusca was, however, only made while this work was
in the press, and it has been found impossible at this late stage to do
full justice thereto and avoid some minor inconsistencies in the text.

CHAPTER II

GEOLOGICAL FRAMEWORK OF THE SOUTH ATLANTIC
SECTION A. THE WESTERN SIDE OF AFRICA

For convenience we may divide this region into two portions:

(i) that from the extreme south of the Cape up to the Cunene
River, of which the geology is now firmly established, while forma¬
tions younger than the Triassic are scarcely represented, and (2)
that from the Cunene River northward, for which reliable data are
often ’wanting, while the coastal strip, just as in the opposed section
of Brazil, is made up largely of marine Cretaceous and Tertiary
deposits.

(1) The southern section ,9 embracing part of the Cape Province
and Territory of Southwest Africa (formerly German Southwest
Africa), displays a great stretch of Archaean rocks from the Cunene
River southward to Van Rhynsdorp, having a northeasterly strike
in the Swakopmund-Windhoek region. Younger, though probably
of Cambrian or pre-Cambrian age, is the Nama system, with a basal
series of conglomerates and quartzites reposing unconformably on the
crystallines, followed by limestones, dolomites, and shales, and these
by red sandstones, red and green shales, and gray and red quartz¬
ites. Though nearly flat -lying inland, e.g., at Kuibis, this formation,
on approaching the coast, suddenly displays folding along axes
following the ocean margin closely, from Liideritz to the mouth of the
Olifants River continued with a south-southeasterly to southeasterly
strike through the Western Province of the Cape. These crumplings ,
which were accompanied by intrusions of granite, are of pre-
Devonian age, but in the south a renewal of movement took place
along them in late Carboniferous times.

Upon a worn-down surface of these rocks was deposited the
triply-divided Cape system some 3,300 meters in thickness, widely
distributed over the southern third of the Cape Province. The
Lower Devonian Table Mountain sandstone at the base, some 1,600
meters thick, is composed of unfossiliferous, whitish, hard sandstones
and grits characterized by tiny pebbles of white or gray vein-quartz
and sometimes of red jasper, while current-bedding is conspicuous.
An important feature is the occurrence of a fine glacial horizon some
700 meters above the base, the material having been derived from
some locality lying out in the present Atlantic.

Then follows the Bokkeveld series of shales and sandstones, with
its Lower-Middle Devonian “Austral” invertebrate fauna and above

• For fuller details see Du Toit (1926).

GEOLOGICAL FRAMEWORK OF THE SOUTH ATLANTIC

it the Witteberg series (upper Devonian-lower Carboniferous) of
white quartzites, with some poorly preserved plant remains. The
source of all these Palaeozoic sediments lay in the north and north¬
west. In the neighborhood of the Olifants River mouth these beds
are lying nearly flat, but on proceeding southward folding is dis¬
covered that follows the much older south-southeasterly directed
crumplings, while near Ceres a second series of foldings appears with
a general west-east trend continuing to the Indian Ocean ; the moun¬
tainous belt thus formed is known as the “Cape Fold ranges. ”

South of latitude 33 ° the Witteberg passes up without a break
into the upper Carboniferous glacials of the Dwyka series, which
constitutes the lowest member of the Karroo system, and which, par¬
taking in the above-mentioned foldings, possesses a thickness of
over 400 meters and seems to have been largely deposited in standing
water by ice-sheets originating in the north. North of the thirty-
third parallel the tillite is found undisturbed, but transgresses across
the Cape system and older groups to rest upon the Archaean, while
the floor beneath it becomes uneven and in good exposures reveals
typically striated roches moutonnZes . The horizontal tillite is a true
ground-moraine and can be traced through Calvinia and Bushman-
land to appear again beyond the Orange River, whence it con¬
tinues northward in Southwest Africa up the Fish River Valley to
Mariental, but has not yet been recognized north of that point.

The succeeding beds, sometimes sharply defined, but often
carrying small erratics, compose the upper Dwyka Shales and pass
up into a zone of white-weathering carbonaceous and pyritic shales
with occasional casts of the small reptile Mesosaurus , and, together
•with some dolomite and chert, constitute the horizon of the “White
band, ” the thickness of these post-glacial beds being from 150 to 160
meters, approximately. These strata are recognizable from Robert¬
son in the south to Mariental in the north, but fragments of Meso¬
saurus have been obtained from the Kaokoveld in latitude 20° 45'.
All this is instructive when comparison is being made with the almost
identical Iraty shales of Brazil with this similar zone fossil. No coals
occur in the Dwyka shales, though the Brazilian seams appear to be
on the corresponding horizon.

The White band passes up in the southern Karroo into the Ecca
series, a thick group of greenish, bluish, and sometimes purplish
shales and flagstones with calcareous nodules and dark-green or gray
sandstones that have yielded silicified wood and the Gangamopteris
flora, but to the northeast and to the north entirely different facies
in the series have been developed. For instance, in Calvinia the
group is composed almost entirely of dark-bluish, soft shales, while
in the southern Kalahari and to the northeast of Keetmanshoop the
strata are now largely red, the formation consisting of deep-red and

8 GEOLOGICAL COMPARISON OF SOUTH AMERICA WITH SOUTH AFRICA

green-blue shales with brown-weathering calcareous bands and soft
yellowish and reddish sandstones, a facies closely comparable with
the second and third stages of the Paganzo system of western Argen¬
tina and also somewhat like the Estrada Nova group in Uruguay. In
the Transvaal, on the other hand, the overlap of the several sub¬
divisions of the Dwyka and Ecca has taken place on to the thin
glacial conglomerate or else on to the pre-Karroo rocks, while a
fluviatile and thinner phase of the Ecca has led to the production of
the Transvaal and Natal “Coal Measures,” a group of pale grits,
conglomerates, arkoses, and sandstones, with dark micaceous shales
and seams of coal often from 2 to 8 meters in thickness. The flora is
the ‘ ‘ southern ’ ’ one, allied to that of the Karharbari of India or the
Greta stage of New South Wales, but with some “northern” ele¬
ments, a Lower Permian age being indicated.

The succeeding Beaufort series, well over 1,000 meters thick, in
the southwest, is made of greenish mudstones and shales, often varie¬
gated and carrying calcareous concretions, together with yellowish
felspathic sandstones, the beds being conspicuously red and maroon
near the top. Small local depositional unconformities are common
and the beds are decidedly of the “interior basin” type. A fairly
abundant reptilian and amphibian fauna and a scanty flora allied to
that of the Damuda of India and Newcastle of New South Wales,
collectively indicate an age covering the upper Permian and lower
Triassic. This formation is unrepresented to the northeast in the
central Transvaal and to the northwest in Southwest Africa.

The Stormberg series embraces the plant- and coal-bearing
Molteno group of grits, sandstones, and gray and blue shales, the
striking deeply-colored group of the Red beds and massive contrasting
cream or pink Cave sandstone and finally the Drakensberg volcanics,
the whole assemblage representing the upper Triassic, Rhaetic, and
just possibly the Liassic. While conformable to the Beaufort in the
south, this series transgresses across the Ecca or even the pre-Karroo
rocks in the Transvaal, Southwest Africa, and Southern Rhodesia, so
that the Red beds, Cave sandstone (and its equivalents, the Bushveld
and Forest sandstone) and basalts come to cover wide tracts without
the intervention of the Molteno or older groups, a feature paralleling
the conditions to be found in South America in the case of the Trias-
Rhaetic beds. The series is well developed in the Kaokoveld, where
it makes the coast-line for quite a considerable distance.

The Molteno flora with its characteristic genus Thimifeldia, is
extremely like that of the “Rhaetic” of western Argentina, though,
the vertebrates ( saurischia and pseudosuchia ) of the Red beds and
Cave sandstone confer an age not younger than Rhaetic for these
succeeding sediments. The Basaltic lavas cover broad areas and
must have had a much wider extension formerly; they exceed 400

GEOLOGICAL FRAMEWORK OF THE SOUTH ATLANTIC

meters in depth in each of the main areas, the maximum thickness
known being about 1,300 meters. Dolerite sills and dikes, closely
related to the lavas, are most abundantly represented in the Karroo
beds from Sutherland and Beaufort West in the south right up into
Southwest Africa, a feature closely paralleled in the Parana Basin
in Brazil.

Cretaceous (Neocomian-Wealden) beds and Tertiaries (Eocene-
Pliocene) are represented within the Coastal Belt of the south of the
Cape, but no undoubted marine Cretaceous is known along the
Atlantic shore south of the Cunene River nor directly opposite in
South America.

(2) In the less known northern area Cretaceous and Tertiary
beds, largely marine in origin, fringe the coast from Lobito Bay in
Angola up to French Congo, widening out where traversed by the
Cuanza and Congo Rivers, while in the former region the strata are
actually flexed along axes concave towards the west and are also
faulted. Dipping beneath them in places are the Dombe sandstones
and in the Congo section the “Gres sublittoraux ” of Fourmarier,10
which have been regarded by Choffat as Lower Cretaceous, but by
others as of Triassic age. The Albian of Benguella is of importance
because of the presence of certain forms common or allied to the
Sergipe Cretaceous of Brazil, as pointed out by Kossmatt, Newton,
Gregory, and others.

The plateau to the east of Benguella, formed of crystallines and
belts of ancient sediments, is crowned with the Bihe sandstone,11
which is probably merely the fringe of the Lubilache series that
covers such an enormous area within the Congo Basin, with its
western boundary passing through Leopoldville northward to the
borders of the Cameroons, a distance of over 1,500 km. This forma¬
tion, several hundred meters thick, is composed' of horizontal friable
white, yellowish, or reddish sandstones, often displaying curious sur¬
face silicification. On the eastern side of this immense basin they
repose upon, but quite possibly to some extent pass laterally into,
the shales and sandstones of the Lualaba series. The age of these
groups, as determined from some fish and crustacean remains, is
Triassic or Rhaetic and they correspond therefore with the Stormberg
series farther to the south. In the west the Lubilache generally rests
with unconformity upon the slightly folded strata ascribed to the
Kundulungu series, a group of deep-red shales and micaceous flag¬
stones alternating with gray or light-red sandstones and becoming
more felspathic and coarser toward the summit. There are serious
differences of opinion as to the age of this formation as seen in the
Lower Congo or in French Congo, which can not be settled, owing

10 Fourmarier (1924). 11 Gregory (1916), p. 523.

10 GEOLOGICAL COMPARISON OF SOUTH AMERICA WITH SOUTH AFRICA

to the absence of fossils, but a Permian or Carboniferous age is just
possible, and if so, the group would correspond to the lithologically
similar Estancia beds of Bahia and Sergipe.

The Kundulungu in turn rests disconformably upon the system
“ Schisto-calcaire, ” a group unconformable to the pre-Cambrian
complex, having a basal conglomerate stated by Delhaye and Sluys 12
to be largely of glacial origin, followed by over 1,000 meters of lime¬
stones and dolomites, occasionally oolitic, but as yet not proved
fossiliferous. They either correspond with the Otavi dolomite
(Nama) of Southwest Africa — probably Proterozoic — or are of early
Palaeozoic age and hence possibly comparable with the Bambuhy
series of eastern Brazil. These beds display strong foldings directed
nearly north-northwest, crossed by a set at right angles thereto,
along the latter of which a renewal of movement occurred probably
in the Permian as well as in still later times.

From Cameroons the coast of Africa turns abruptly westward
and a region13 is reached displaying many points of similarity with
the Pernambuco-Maranhao territory of Brazil. Along the low-lying
coast, extending from Cameroons to Accra, with a tongue reaching
into northern Nigeria, is a curving belt of marine Tertiaries, in which
zones so far back as the Eocene are to be found, resting upon either
Cretaceous or ancient formations and passing beneath younger
deposits. Bituminous shales and lignites are known from the earlier
tertiaries in several areas and can be compared with the Eocene
bituminous shales with fish remains in Alagoas and perhaps Maran-
hao. Much of the western part of Africa was inundated by the
Cretaceous ocean, and wide tracts of the hinterland are covered by
marine beds belonging to various stages of that epoch, just as is so
marked a feature of Ceara, Piauhy, and Maranhao. On both sides of
the Atlantic these strata have locally been affected by post-Creta¬
ceous movements.

Among the older formations might be mentioned the Buem series
on the eastern side of the Volta River in Togoland, composed of con¬
glomerates, arkoses, quartzites, and shales, of which certain con¬
glomerates have been regarded as of morainic origin by Koert and
hence of Permo-Carboniferous age ; Lemoine classes them, however,
in the Devonian. Conspicuous is the tectonic line of the Atacora
Range south of the Niger in Dahomey — the “Saharides” of Suess —
in which a belt of folded quartzites and schists, flanked by crystal¬
lines, ascribed to the Silurian, but probably older, strikes north-
northeastward from the Gold Coast and thence at intervals into the
Sahara, where the folds now trend more nearly northward ; associated
is the Tarkwa series in Gold Coast Colony with northeastward strike
and certainly pre-Palasozoic.

12 Delhaye and Sluys (1921).

13 Lemoine (1913).

GEOLOGICAL FRAMEWORK OF THE SOUTH ATLANTIC

This brings us to the consideration of the undoubted Palasozoic
rocks of western Africa and central Sahara. On the borders of Sierra
Leone and French Guinea, resting unconformably on schistose rocks,
is an undulating sandstone formation carrying Silurian (Wenlock)
graptolites,14 apparently the beginning of the huge area of horizontal
sandstones on the upper Niger building up the plateau of Homboi
(“Bandiagara sandstone”) and south of the great bend of the Niger,
but which have not as yet been proved fossiliferous. To the north¬
east the Silurian of Tuareg and Air is folded and overlain by gently
dipping Lower Devonian possessing a fauna including in addition to
European forms, not only some from North America, but certain
from the Bokkeveld as determined by Haug.15 Future work will
doubtless add largely to the known area of Palaeozoics in this part of
Africa. Of great importance too is the occurrence of the Middle
Devonian in a small down-faulted block at Accra on the Gold Coast,
with a “Hamilton” fauna,16 while slates, provisionally placed in the
Lower Carboniferous because of certain poorly preserved mollusca —
but possibly Devonian — are known at Sekondi to the west of Accra.

Undoubted pre-Mesozoic marine beds have not yet been found to
the southeast in Cameroons, and the presence of this wide, though
interrupted belt extending from Sierra Leone into the Sahara, in
which marine Palaeozoic beds have been developed, is of immense
importance, inasmuch as it shows correspondence with the broad,
shallow syncline of marine Silurian, Devonian, and Carboniferous
strata within the lower Amazon Valley in which similar faunal ele¬
ments are actually present.

SECTION B. THE FALKLAND ISLANDS

These remarkable islands, of which a brief geological sketch can
not be omitted, constitute a most striking link between South Africa
and South America, despite the fact that they are situated only a few
degrees from Patagonia and well down below the fiftieth parallel.
Our knowledge concerning them has been enormously extended
through the work of Andersson 17 and after him Halle,18 with H. A.
Baker 19 just recently, while the Devonian molluscan fauna has been
discussed by J. M. Clarke20 and the Gondwana flora described by
Halle, Seward and Walton.21

The dominant Devono-Triassic succession has been affected by
two main tectonic structures. The more important of these, marked
by strong folding and some faulting, traverses the northern part of
East Island, trending west to west-northwest and curving more to the

14Dixey (1925), p. 213; Lecointre and Lemoine (1925).

16 Haug (1905).

16Kitson and Morley Davies (1925). 19 Baker (1923).

17 Andersson (1907). 20 Clarke (1913)* P- 55» P* 32^.

18 Halle (1912). 21 Seward and Walton (1923).

12 GEOLOGICAL COMPARISON OF SOUTH AMERICA WITH SOUTH AFRICA

northwest through the northern side of West Island, with some
parallel subsidiary flexuring in the center of that land; the other
structure crosses nearly at right angles, striking south west ward along
both shores of Falkland Sound. In the southern side of East Island
and the southwestern side of West Island the beds, on the contrary,
undulate slightly or are flat.

The lower Devonian sandstones are restricted to the southwestern
side of West Island, resting unconformably upon crystallines at
Cape Meredith and having a thickness of many hundred meters.
The series is extraordinarily like the Table Mountain sandstones of
the Cape Province, consisting of a group of unfossiliferous, pale,
false-bedded sandstones and quartzitic sandstones with some red
micaceous shales at the very base, while small pebbles of white vein-
quartz are common, making in places conglomerates. It passes
beneath a group of slaty rocks, shales, flagstones, and sandstones that
has yielded a typical “austral” Devonian fauna, overlain by similar
beds with lepidodendroid plant remains and thus like the Bokkeveld
series of the Cape. Of the mollusca, some 20 species are common
to the latter and some 2 5 to the equivalent Devonian of South Amer¬
ica, including in each case several trilobites, besides other closely
allied forms. This group is succeeded by quartzites and quartzitic
sandstones and interlaminated shales that correspond with the
Witteberg series. Baker has pointed out these surprising resem¬
blances with the Cape system, not only lithologically, but in regard
to thickness as well, so far as such can be made out in the folded
ranges of East Island.

The Gondwana beds are referred to as the Lafonian system,
having a thickness of possibly over 3,000 meters and occupy the
southern half of East Island, but are brought down by folding in a
few localities in West Island. At the base are glacial boulder-beds
about 650 meters thick, identical in their characters with those of the
, Dwyka tillite, usually folded and cleaved, with striated erratics often
traversed by regular jointing; underneath them Baker has discovered
some quartzite surfaces with striations running from north to south,
presumably glaciated floors. Some passage beds with small inclu¬
sions lead up into the Lafonian sandstone, and this in turn into
“banded siltstones, ” apparently seasonally banded “varve” rocks
representing glacial material deposited in fresh water.

Next comes a huge group of alternating brown, yellow, gray, and
green mudstones, shales and similarly colored sandstones and hard
greenish sandstones in which occur members of the Glossopteris
flora. The form identified by Halle as Gangamopteris is regarded by
Seward and Walton22 as more probably a Glossopteris , with which
occur G. browniana, G. indica, Voltzia , and several species of

22 Seward and Walton (1923), p. 324.

GEOLOGICAL FRAMEWORK OF THE SOUTH ATLANTIC

Phyllotheca and Dadoxylon, evidently an Ecca-Beaufort flora. The
highest beds, exposed on the eastern side of Falkland Sound, have
yielded Neocalamites carrerei (Zeill.), suggestive of a Triassic age.

Dolerites, just like those injected into the Karroo system at the
close of the Rhaetic, pierce the strata at a number of places, signifi¬
cantly avoiding the northern folded belt, but frequently possessing a
northeast-southwest trend. Not improbably the westerly to north¬
westerly directed foldings correspond in age with those striking
nearly east-west in the Cape, which we know were initiated at the
very close of the Palaeozoic, but were renewed in mid-Cretaceous
times, and from which dolerite is absent. The Western Province
of the Cape displays in addition another set of foldings trending
southwest or west-southwest.

The precise place of the Falkland Islands, stratigraphically,
lithologically, and structurally, with reference to the Cape and to
Argentina, will be discussed at a later stage (Chapter VI), when it
will be shown that they display characters consistently intermediate
between those of the two countries, though somewhat more closely
allied with the former.

SECTION C. SOUTH AMERICA23

Commencing in the north, the outstanding feature is the great
syncline of Lower Pakeozoics, much covered by Tertiary and Quater¬
nary deposits, in the Amazon Valley, trending eastward from Manaos
to Para, in which direction its axis deviates towards east-northeast.
In this trough marine strata of Silurian, Devonian, and Carbonif¬
erous ages are all involved, resting upon the Archaean, which bounds
the structure for immense widths, both to north and south.

Eastward in Maranhao, Piauhy, Ceara, Parnahyba, and Pernam¬
buco there is a wide fringe of Tertiaries, and no Palaeozoics are known
to occur, if we ignore the rather doubtful series of Serra Grande, while
inland in the first two States Permian and Triassic Gondwana sedi¬
ments spread over a wide area, reposing mainly on crystallines. In
Alagoas, Sergipe, and the adjoining part of Bahia undoubted Permian
and possibly upper Carboniferous form belts rest on the (probably)
pre-Devonian basement and display a certain amount of folding.
Save for them and the similar patch in the southern end of Bahia,
Gondwana beds do not reach the coast of Brazil, except in the neigh¬
borhood of Torres.

Inland from Bahia is an extensive trough of folded lower Palaeo¬
zoic beds — mainly slates and limestones, probably Ordovician — as
well as much older formations, striking southwestward from near the
great bend in the Rio Sao Francisco, following up the valley of that
river almost to the boundary of Minas, which feature is continued

23SeeBranner (1915) (1919).

14 GEOLOGICAL COMPARISON OF SOUTH AMERICA WITH SOUTH AFRICA

beyond with similar trend through Sao Paulo and Parana in the more
closely folded and altered condition to reappear in Uruguay. This
lengthy tectonic structure, running approximately parallel to the
Atlantic coast, has been termed the “Brasilides” by Keidel.

Occupying the whole of the Upper Parana drainage area is the
great but shallow “Parana Basin,” made of Gondwana beds, called
the Santa Catherina system, deposited upon a platform of crystal¬
lines and folded Ordovician, but in parts of Parana and Matto
Grosso upon nearly horizontal lower Devonian strata like those of
the Cape; its boundaries have been determined by erosion on all
sides except to the west of the Paraguay and Lower Parana Rivers,
where the beds disappear beneath the geologically recent Neogene
formations. A large part of east-central Brazil is, furthermore,
covered by horizontal Cretaceous and perhaps Tertiary sandstones
of continental type, in places concealing the Santa Catherina beds.

Passing over the wide stretch in Eastern Argentina, beneath
which these Gondwana strata have been proved by deep borings,
those beds reappear in the west at intervals within a huge region from
Bolivia southward to Cordoba and Mendoza, where they, together
with Palaeozoics beneath and Cretaceo-Tertiaries above, have been
involved in the Andine movements, with general strike either north
or a little east of north ; here they are known as the Paganzo system.
Farther to the south similar strata, from Devonian to Permian in
age, build the ranges between Buenos Aires and Bahia Blanca with
southeasterly trend, structures termed the “ Gondwanides ” by
Keidel24 and regarded by him as the continuation of the Southern
Fold ranges of the Cape, involving as they do precisely similar
and equivalent formations.

The equivalent systems of Santa Catherina and Paganzo gener¬
ally begin with a glacial formation, which corresponds with the
Dwyka tillite of South Africa and is followed by plant- and often
coal-bearing lower Permian beds with the “ Glossopteris flora” and by
higher Triassic and Rhaetic rocks, but an important intraformational
break exists, extending perhaps over most of the region. At the top
come the enormously widespread basaltic effusions of Parana,
though not restricted to that region, being also represented in
Maranhao and in certain of the remnants in the pre-Cordillera as
well as in Patagonia, where, however, the bulk of the volcanics
appear to be of acid composition, largely overlain by nearly flat
lying Cretaceous and Tertiary beds.

The western limits of Gondwanaland are not exactly known, as
the Andine belt is largely composed of Mesozoic marine beds and
volcanics, all intensely folded and injected with igneous matter.

24 Keidel (1916 and 1922).

GEOLOGICAL FRAMEWORK OF THE SOUTH ATLANTIC 15

SECTION D. GENERALIZED COMPARISONS BETWEEN
THE TWO CONTINENTS

Confining attention in each case to a strip some 45 degrees in
length by 10 in breadth, we shall now proceed to compare the two
stretches, namely, the tract extending from Sierra Leone to Cape
Town on the one side with that from Para to Bahia Blanca on the
other ; furthermore, whenever the direction of any structural feature
has to be mentioned, such will be given with reference not to the
meridian, but to the coast-line near at hand.

In each continent:

(1) The foundation rocks consist of crystallines of pre-Cambrian
age and certain belts of infolded pre-Devonian sediments of various
though mostly undetermined ages, but generally corresponding
lithological characters,

(2) In the extreme north, marine Silurian and Devonian beds,
only slightly disturbed, rest unconformably upon this complex,
occupying a broad syncline trending obliquely to the coast-line,
namely, between Sierra Leone and Gold Coast and underlying the
estuary of the Amazon.

(3) Farther to the south, belts of Proterozoic and early Palaeo¬
zoic strata, mainly quartzites, slates, and limestones, strike nearly
parallel to the coast, being gently flexed in the north, but becoming
more disturbed toward the south, where they are invaded by granitic
masses, for example, in the region between Liideritz and Cape Town
and that between the Rio Sao Francisco and Rio La Plata.

(4) Corresponding to the nearly flat-lying Devonian of Clan-
william is its all but identical counterpart in Parana and Matto
Grosso.

(5) More to the south we find the Devono-Carboniferous of the
southern Cape paralleled by the terrain appearing a little to the north
of Bahia Blanca, passing up conformably into the Carboniferous
glacials and Permian sediments, both successions having been
intensely crumpled under Permo-Triassic and Cretaceous move¬
ments that display similar orientations.

(6) Traced northward, the tillites in each case become horizontal
and transgress across the Devonian to rest upon a glaciated pene¬
plain formed by these and by older rocks ; farther to the north they
fail.

(7) The glacials are in each case overlain by continental Permian
and Triassic strata with the “ Glossopteris flora, ” covering enormous
areas, followed by vast outpourings of basalts and penetrated on an
extensive scale by dolerites of presumed Liassic age.

(8) These Gondwana beds extend northward from the Southern
Karroo to the Kaokoveld and from Uruguay to Minas Geraes.

(9) Further great detached areas occur in the north, in each case

16 GEOLOGICAL COMPARISON OF SOUTH AMERICA WITH SOUTH AFRICA

some distance inland, in the Angola-Congo and the Piauhy-Maran-
hao regions.

(io) An intraformational break is widespread, though commonly
there is no angular unconformity between late Triassic and early
Permian beds. In certain areas, however, the former may rest with
visible discordance on tilted Permian or pre-Permian formations.

(n) Tilted Cretaceous beds occur on the coast only in the Ben-
guella-Lower Congo and Bahla-Sergipe areas.

(12) Horizontal Cretaceo-Tertiary, both marine and continental,
cover great extents between Cameroons and Togoland and in Ceara,
Maranhao, and also more to the south, while the extensive deposits
of the Kalahari can roughly be paralleled with the Neogene and the
Quaternary Pampean of Argentina.

(13) In setting down this generalized summary, the important
link constituted by the Falkland Islands must not be overlooked.
Their folded Devono-Carboniferous succession is all but indistin¬
guishable from that of the Cape, while the Lafonian closely parallels
the Karroo system. Strati graphically and structurally the Falklands
have their place with the southwest of the Cape and not with Patagonia
(Chapter VI) .

(14) From the palaeontological viewpoint, attention should be
focussed on: ( a ) the “austral facies” of the Devonian of the Cape,
Falklands, Argentina, Bolivia, and Southern Brazil, in contrast to
the “boreal facies” of northern Brazil and central Sahara; ( h ) that
unique reptilian genus Mesosaurus from the Dwyka shales of the
Cape and Iraty shales of Brazil, Uruguay, and Paraguay; ( c ) the
Gangamopteris-Glossopteris flora, with a small admixture of northern
forms within the Lower Gondwana beds in the south of each country ;
(d) the Thinnfeldia flora of the Upper Gondwana of the Cape and
Argentina; ( e ) the Neocomian (Uitenhage) fauna in the south of the
Cape and northwest of Neuquen in Argentina; (/) the Northern or
Mediterranean facies of the Cretaceous and Tertiary faunas north
of the Tropic of Capricorn; and (g) the South Atlantic- Antarctic
facies of the Eocene (San Jorge formation) of Patagonia.

(15) The geographical outlines of Africa and South America are
amazingly similar, not only in the main, but even as to detail ; more¬
over, excepting in the north, the fringe of Tertiaries is of small width
and the presence of those beds of little moment therefore.

On following the various groups embraced between the Devonian
and the Rhaetic of the two continents in a direction away from the
Atlantic shores an amazing generalization shows itself, namely, that
the variation in facies of these several formations commonly dis¬
closes greater divergences within distances of say from 5 to 1 5 degrees
of arc than those actually noticed on comparing the developments

European equivalents

Cape Province

Falkland Islands

Sierra de la Ventana

Liassic.

’ Basalts.

Rhaetic.

Cave sandstone.

Red beds.

Triassic.

-4— 1

k Molteno beds.

Beaufort.

•

4-J

’ Sandstones and
shales.

Permian.

Ecca.

C/3

a *
a

• H

Shales, clay-
stones, etc.

Pillahuinc6 beds.

Upper Carboniferous.

Dwyka

' White band.

Upper shales.

Glacials.

Shales, sand¬
stones, etc.

. Glacials.

Shales.

Glacials.

Lower shales.

Middle and lower

Carboniferous and
middle Devonian.

Lower Devonian and
uppermost Silurian.

Cape system

_ /V _ _ _ _ _ _ _ _

Witteberg quartzites
and shales.

Bokkeveld beds (fossil -
iferous) .

Table Mountain sand¬
stones.

Quartzites, sand¬
stones, and shales.

Fossiliferous shales
and sandstones.

Barren sandstones.

Greywackds.

Fossiliferous slates.

Sierra de la Ventana
quartzites.

Paganzo system

European equivalents

Cape Province

Falkland Islands

Sierra de la Ventana

Liassic.

1-4

Basalts.

Rhaetic.

Cave sandstone.

Triassic.

+->

Red beds.

. Molteno beds.

Beaufort.

4-»

Sandstones and
shales.

Permian.

Ecca.

-*->

a ■

Shales, clay-
stones, etc.

Pillahuinc6 beds.

P-t

Upper Carboniferous.

White band.

Upper shales.

'£

Shales, sand¬
stones, etc.

Shales.

Glacials.

. Glacials.

Glacials.

Lower shales.

Middle and lower

Carboniferous and
middle Devonian.

Lower Devonian and
uppermost Silurian.

4->

< V

Witteberg quartzites
and shales.

Bokkeveld beds (fossil-
iferous) .

Table Mountain sand¬
stones.

Quartzites, sand¬
stones, and shales.

Fossiliferous shales
and sandstones.

Barren sandstones.

Greywackds.

Fossiliferous slates.

Sierra de la Ventana
quartzites.

Table I. — Strati graphical Table Showing the Devono-Lias Succession in South America and South Africa

(The wavy line indicates an unconformity.)

San Juan — La Rioja

V. Red conglomerate,
etc.

IV. “Rhaetic.”

III. Stage.

1 1. Stage.

Shales, etc.
Glacials.

Cardiopteris beds.
Glacials.

Barreal

V. Red conglomerate.
IV. “Rhaetic.”

’G

g Glacials.

Marine beds with Produc-
tus and Spirifer.

Slates, greywack6s, and sandstones.

• ’ — i

Northern Argentina and
Southern Bolivia

Marls.

Limestone and Dolomite.

Upper sandstones (Macha-
reti).

Mandiyuti.

Oquita.

Materal.

Productus beds.

Sica-sica beds.
Huamampampa sandstones.
Conularia and Crinoid beds.
Ida sandstones.

.£

4-5

Parand Basin

Serra Geral volcanics.
Botucatti sandstone.

Rio do Rasto.

Estrada Nova.

(upper part)

Estrada Nova.

(lower part)

Irat£.

f Palermo.
<u i

11:

'g r

jg j Glacials.

Bonito.

Ponta Grossa shales.
Furnas sandstone.

P-,

Maranhao

.|3 f Basalts.

*2 I Red sandstones.

(?)

Southwest Africa

North

g ( Basalts.

•M

Kaoko beds.

{Shales and sand¬
stones with
Psaronius.

South

Basalts.

Ecca.

White band.
Upper shales.
Glacials.

Transvaal

1-4

Basalts.

Bushveld sandstone
Bushveld marls.

Coal measures.

stf r
44

b 1 Glacials.

GEOLOGICAL FRAMEWORK OF THE SOUTH ATLANTIC

nearest the two opposed shores, although the ocean between is no
less than from 40 to 70 degrees in breadth. This observed arrange¬
ment is considered to constitute the most telling argument in favor
of the conception that the two continental masses were in the past
geographically closer to each other , which is actually the keynote of
the Displacement or Disruption Hypothesis. Evidence for this
momentous assertion will be found in the following pages and the
problem reviewed in Chapter VII.

For convenience, the accompanying correlation table has been
introduced at this stage to indicate the stratigraphical succession in
the type areas to be dealt with in detail below.

CHAPTER III

ARGENTINA AND BOLIVIA

SECTION E. THE SIERRAS OF THE DISTRICT OF BUENOS AIRES

Rising out of the plain of Pampean deposits (late Tertiary to
Quaternary), here close upon 200 meters above sea-level, are the two
well-known chains of ancient rocks lying to the south and southwest
respectively of Buenos Aires.

(1) The Sierra de Tandil25

The first of these stretches from Mar del Plata on the Atlantic
coast in a direction a little to the west of northwest past Tandil to
Olavarrfa — a distance of over 300 km. with a mean breadth of about
50 km. — being composed of a series of small chains and isolated
hills with frequent interruptions and nowhere exceeding an altitude
of 450 meters. The features displayed are those of a buried and
partially exhumed mountain chain, and along its margins the belt is
bordered by inkers of the hard rocks projecting through the soft
mantle of the plain.

! The formation consists largely of pre-Palasozoic granite, on which
rests unconformably a basal quartzitic member followed by dolomite,
quartzite, slate, white limestone, etc., to a thickness of fully 150
meters. In contrast to the distinctly younger beds of the Sierra de la
Ventana, the strata in the Sierra de Tandil are but gently flexed, and
are often lying nearly flat, the harder members producing table-
topped hills; on the coast the nearly horizontal quartzites have
determined Cape Corrientes. This flexuring follows two directions
mainly, namely, west -northwest to east-southeast and one almost at
right angles thereto, i.e.} north-northeast to south-southwest. The
latter represents the mid-Palaeozoic “Brasilides, ” as Keidel has
called them, which have been crossed and modified here by the first-
mentioned set of the Permo-Triassic ‘ ‘ Gondwanides, ’ ’ so finely
displayed in the belt to the southwest, which foldings, although of
considerable intensity in that quarter, seem to have faded out to the
northeast before reaching Uruguay.

Where seen by me in one of the outliers of the Dos Hermanos
(“The Two Brothers”), near Olavarrfa, the quartzites, resting on a
pedestal of red granite, are white, hard, and fine-grained, though
somewhat coarser at their base and not unlike the Kuibis quartzites
of the Nama system of Southwest Africa, that are also followed by
slates and limestones. They are, however, presumed to be of Silurian

25 Aguirre (1879); Hauthal (1896, 1901); Valentin (1894); and Nagera (1919), who
gives a bibliography.

ARGENTINA AND BOLIVIA

or more probably of Ordovician age, because of impressions referred
to Arthropliycus harlani Hall, in certain of the quartzites at Balcarce 26
while Siemiradski reported finding Stromatopora and A try pa in the
dolomitic group,27 though such does not appear to have been con¬
firmed.

It should be observed that this belt stands wholly isolated in the
Pampean formation, that it is over 400 km. distant from the possibly
equivalent strata in Uruguay and 150 km. from the Palaeozoics of
the Sierra de la Ventana and Pillahuinco, and that the few bore-holes
that have penetrated the Pampean covering have only proved
granite ; for example, that at Buenos Aires and at Telen in the district
of La Pampa to the west.

(2) The Sierra de la Ventana

The Fold-ranges, among which is embraced this most important
of the sierras, lie not far to the north of Bahia Blanca and occupy a
tract some 180 km. long by 50 km. at its widest. They include the
Sierra de Puan, Sierra del Chaco, and Sierra de la Ventana proper in
the southwest and west, and the Sierra de Bravard, Sierra de las
Tunas, and Sierra de Pillahuinco on the northeast, and make a
sweeping double curve with general strike from southeast to north¬
west, bending to the west in the latter direction. In the heart of the
ranges the Rio Sauce Grande courses along a strike valley that
generally follows the Tillite zone. As with the Sierra de Tandil, the
Pampean formation laps around the base of the rising ground and
enters many of the valleys.

The geology has been described by Aguirre, Hauthal, and
Schiller,28 and more particularly by Keidel,29 who has not only given
the most detailed and accurate account, but by the discovery of the
Carboniferous tillite was first able to point to the wonderful simi¬
larity with South Africa and show that the ranges, structurally as
well as geologically, appeared to form the continuation across the
Atlantic of the Fold-ranges of the Cape Western Province. The
writer’s researches bear out the value of Keidel’s work and percep¬
tion, for in only one essential does his interpretation differ from that
of this Argentine geologist, namely, in the stratigraphical position of
the Pillahuinco beds. To the visitor from South Africa the resem¬
blances with that country are simply astounding, such being the case
not only with the major elements, but in so many minor respects, as
well as in lithological details regarding the tillite and in the presence
and attitude of the Tertiary “high-level gravels.”

The cross-section from southwest to northeast passing through

26Ndgera (1919a), p. 7.

27 Siemiradski (1893).

28 Aguirre (1891); Hauthal (1892, 1896, 1901, 1904); Schiller (1907).

29 Keidel (1916), also (1922).

20 GEOLOGICAL COMPARISON OF SOUTH AMERICA WITH SOUTH AFRICA

two

the railway station of Sierra de la Ventana (formerly called Rio
Sauce Grande) would show (Fig. i) on the southwest a closely folded

and inverted succession of Palaeozoic strata
in which the softer beds display a strong
cleavage that is dipping at a high angle
to the southwest (shown by broken lines
in the diagram).

The lowest member — a thick, whitish,
quartzitic sandstone formation, the equiv¬
alent of the Table Mountain sandstone of
the Cape — builds the main range, which
in its various aspects strongly recalls the
chains of the Langebergen, Outeniqua, and
other coastal barriers of the Cape, and
which culminates in the Cerro de los Tres
Picos (1,280 meters); farther along the
crest is the peak pierced by the famous
“ventana” or window, from which the
range takes its name. On its southwestern
foot the basement granite is reported to
crop out near Tomquist and Aguas Blan¬
cas, the contact being an inverted one
apparently. The sloping ground to the
northeast, for a distance of some 5 or 6
km. down to the valley of the Rio Sauce
Grande, is made by the second member , a
series of cleaved slates and greywackes,
corresponding to the Bokkeveld and
Witteberg series of the Cape, in which
the folding can at times be made out, while
the valley floor, together with the rising
ground just beyond, is composed of a
cleaved greenish tillite, the representative
of the Dwyka glacials.

The stratigraphical position of the
strata to the northeast has hitherto been
in doubt, the folded quartzites and slaty
beds of the Sierra de Pillahuinco having
been regarded by Schiller as the equiva¬
lent of those in the ranges to the south¬
west, a view satisfactorily disposed of by
Keidel, who has nevertheless considered
them as probably of pre-Devonian age.
My observations, however, have shown an
upward passage into them from the tillite,

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ARGENTINA AND BOLIVIA

which goes to indicate that these beds are the equivalent of the
folded Ecca series of the southwestern part of the Cape Karroo
and of the Lafonian of the Falkland Islands, as will be discussed in
the sequel. While the entire succession is thus extraordinarily simi¬
lar to those in the Cape and Falklands, its resemblances to the
equivalent beds represented in the pre-Cordillera of San Juan to the
northwest are, it should be noted, by no means so clearly marked.

(a) The Infra-tillite Succession — To the excellent account given
by Keidel 30 there is little to add. The basal group may possibly be
close on 1,000 meters in thickness, but the intense crumpling in this
section would prevent any exact measurements being made. In the
splendid exposures at the head of the Arroyo San Bernardino the
quartzites (Fig. i, I ) are isoclinally folded in a rather regular fashion,
the succession being of course an inverted one, the pressure, just
as in South Africa, having come from a southerly direction. Owing
to a mishap to a negative, I am unable to give a photograph of
these fine contortions, but one of Beder’s views, published by Keidel,
taken further to the west along the same range, is reproduced, which
will serve to bring out this feature very clearly (Plate I) .

Most of the beds are hard, white, fine-grained quartzite, but
there are darker and faintly greenish varieties and a number of thin,
greenish-gray schistose quartzites and slaty kinds in thinner layers.
One conspicuous shale bed (Plate II, A, and Fig. i, ia) perhaps a few
hundred meters from the top of the series, is 8 meters thick, a dark-
green, silvery slate, with base well defined, which invites comparison
with the well-known ‘ * shale band ” of the Table Mountain sandstone,
but no glaciated pebbles were seen in it or just below it. The upper¬
most hundred meters of strata are distinctly darker than those com¬
posing the range proper, approaching a greywacke in some respects,
the rock being schistose, showing some false-bedding and including
a little grit with quartz fragments and pebbles, which was the only
coarse material seen. The schistose and darker character tends to
obscure the upward passage into the slate group, which, as Keidel
has pointed out, is rapid, though not obvious. That the quartzites
underlie the slates can be shown by a study of their folded junction.

To sum Up, the quartzites have marked similarities to the Table
Mountain series of the Cape ; not to that in the Ceres or Clanwilliam
districts, but to the facies in the south, i.e., Mossel Bay, George, or
Knysna, where it is finer-grained, where quartz pebbles are rarer and
smaller, and where thin layers of dark slates are not unusual.

In the overlying, seemingly thick, group — called the ‘ ‘ esquistos
by Aguirre, the folding can now and again be made out, despite the
strong cleavage. The lowest beds are fine slates, with some bands
of greywacke appearing higher up, while the topmost beds consist

10 Keidel (1916), pp. 11-12; 21-22; 28-29.

22 GEOLOGICAL COMPARISON OF SOUTH AMERICA WITH SOUTH AFRICA

not of quartzites, as in the Cape and Falklands, but of highly cleaved
greywackes, mostly brownish in color and full of feldspar, finer
alternating with coarser varieties, the latter becoming in places quite
gritty, while a few pebbles of dark bluish quartzite were observed.
The marked cleavage obscures both the dip and the folding, but
the topmost bed, in contact with the tillite, is a hard, brown, un¬
cleaved grit.

These strata are manifestly the equivalent of the middle and
upper divisions of the Cape system, much distorted Devonian fossils
having indeed been obtained in several places in the slaty basal por¬
tion of the assemblage, while a specimen inclosed in a sandy rock
approaching a greywacke, which is exhibited in the La Plata Museum,
was derived from this locality. The greywacke, marked (. 2a ) in the
section (Fig. i), is evidently the same bed as is shown on Keidel’s
map of the territory lying a short distance farther to the northwest
along the same strike, and recalls the first or fossiliferous sandstone
of the Bokkeveld series and the Tibagy sandstone of Parana. The
uppermost group of greywackes and occasional slates, which has
so far yielded neither molluscan nor plant remains, is wholly differ¬
ent from the white, fine-grained quartzites with green slaty interca¬
lations of the Witteberg series or those occupying a similar horizon
in the Falklands, and in this very important respect the succession
here differs from those in South Africa and the Falkland Islands.

It is uncertain whether the phyllites and greywackes known from
the Sierra Pintada in the southeastern part of the Mendoza district
are of Devonian age, but, as will be set forth later on (Chapter VI),
the strata in Jachal to the north referred to this epoch and containing
the typical “austral fauna” in their upper part, are in their basal
section no longer white quartzites, but shaly sandstones and sandy
shales with bands of soft, dark sandstone and of a friable nature.
This marked difference in lithology of the basal portion of the
Devonian within the distance of less than 1,000 km. toward the
northwest, as compared with the slight change noted in the distance
of almost 6,000 km. from the Cape or 2,000 km. from the Falklands
can not be overemphasized and will be discussed in Chapter VII.

( b ) The Tillite — In the neighborhood of Sierra de la Ventana
station the lower part of the glacial beds (4a) is but poorly exposed
over the gently undulating ground, but practically continuous out¬
crops can be seen in the higher country to the east of the railway
bridge spanning the Rio Sauce Grande, while excellent artificial
sections are disclosed in the railway cuttings between kilometer
posts 529 and 536. The total breadth of the belt is about 9 km.
The prevailing strong cleavage (Plate II, B), directed southwestward
at an average angle of about 65°, coupled with the unsatisfied charac¬
ter of the deposit, obscures the true behavior of the formation, which

ARGENTINA AND BOLIVIA

accounts for the erroneous interpretations of the section by Hauthal
and others, but a careful study of the attitude of certain shaly or else
quart zitic layers goes to indicate that the formation, though seem¬
ingly dipping southwestward beneath the greywackes in that direc¬
tion, is actually resting upon the latter and as a whole is dipping
northeastward below the strata of the Sierra de Pillahuinco. On the
southwest the folds are isoclinal with axial planes dipping southwest-
ward at nearly 45 °, but along the Rio Sauce Grande flattening has
occurred and thereafter the glacials are but slightly flexed, to pass
ultimately at quite a low angle northeastward beneath the sediments
of the Cerro Bonete. I agree with Coleman 31 that Keidel 32 has over¬
estimated the degree of folding that is present in the railway section,
since, except for one important reversal of dip, the mass is inclined
regularly northeastward, though signs of strong compression are
nevertheless clear. The thickness is difficult to estimate here, because
of the uncertainty as regards that of the lower part of the forma¬
tion, but it is undoubtedly well in excess of the figure given by
Keidel, namely, 60 meters; it would seem to be at the least 200
meters, perhaps more.

The base was studied on the left side of the Arroyo San, Ber¬
nardino, a few kilometers west of the station, the nearest point where
the junction with the hard top of the greywacke group (3) is exposed.
A careful examination showed the tillite to be dipping at 45 beneath
the greywacke, but within the latter are what were taken to be two
narrow infolds of the base of the glacials, certain marginal and other
characters indicating that they were merely the repetition of one and
the same zone. As a rule, the change from greywacke to dark-blue,
fine-grained tillite with small inclusions takes place within a distance
of a few centimeters, while some small pebbles occasionally occur
just within the greywacke itself. At one place a wedge of soft
schistose strata appears just within the latter, including some iso¬
lated pebbles like those in the tillite, all of which makes it practi¬
cally assured that there is a perfectly conformable transition from the
arenaceous into the glacial formation. This conclusion, therefore,
confirms the opinions arrived at by both Hauthal and Keidel.

The condition thus parallels that in the south of the Cape (south
of latitude 330) where no discordance has been detected, though the
change from the one formation to the other is often quite abrupt, but
differs from those in the Tanqua Karroo or in the Falklands, where
the tillite rests upon a slightly striated surface of the underlying
Carboniferous quartzites.

Of the glacial origin of the formation, a discovery first made by
Keidel and since confirmed by Coleman, there can not be the slightest
doubt. All the phenomena displayed duplicate down to minutest

81 Coleman (1918), p. 319* 82 Keidel (1916), P- 25-

24 GEOLOGICAL COMPARISON OF SOUTH AMERICA WITH SOUTH AFRICA

detail those characterizing the Dwyka tillite in the south of the
Karroo. The rock is a hard greenish unstratified material, having
scattered irregularly and sometimes rather sparsely through it inclu¬
sions that rarely exceed 0.5 meter in length. Among the host of rock
types represented, Keidel discovered a lump of fossiliferous limestone,
while noteworthy are certain quartzites and greywackes indistin¬
guishable from those of the Sierra de la Vent ana, but it is important
to observe in the uncleaved condition. Keidel also mentions erratics
of material like the beds in the Sierra de Pillahuinco, but I could find
nothing that could with any confidence be ascribed to those forma¬
tions exposed to the northeast. Well-striated and often faceted
boulders, such as are typical of glacial tills, can be obtained without
difficulty, such as have been figured by Keidel and Coleman.

Like the Dwyka along the south of the Karroo, the Rio Sauce
Grande conglomerate is not one uninterrupted, single body of
morainic matter, for there are several surfaces of discontinuity, which
evidently mark the cessation and subsequent renewal of glacial
activity. At kilometer 535 in a railway cutting is exposed the
sharply defined top to a tillite body with a thin, splintery shale rest¬
ing upon the plane or break and passing up in turn into a normal
tillite. A little higher up there appears a “ gravelly” band of the
kind of material termed in South Africa “gravel Dwyka,” charged
with small angular and sub-angular stones, while next in turn comes
an instance of a “boulder pavement” in which the inclusions within
the top of the lower body of morainic material have all been pressed
down to one level and striated in a direction, so far as can be made
out, north 65° west (true) ; this is overlain by normal tillite. The way
in which the top of each of these pebbles just rises above the surface
of discontinuity, and other features, show that the phenomena are
due to the overriding of the moraine by the ice itself and are not due
to subsequent tectonic movements. Boulder pavements of identical
character have been recorded in the Dwyka and in the Carboniferous
glacials of Cape Wynyard in Tasmania. Furthermore, there is a very
important intercalated zone of quartzitic rocks (Fig. 1, 4b ), probably
lenticular in habit, with a maximum thickness of 40 meters, which
splits the tillite mass, occurring on a horizon about 70 meters from
the top of the glacials building up the outlying peak of the Cerro de
Pillahuinco immediately to the west of the 534 km. post and seen
again on the railway at 533.50 and 533 and running in a belt 1 km.
to the east on the left side of the Arroyo Negro, where it can be seen
to pass below the upper tillite (4c). At 53 1.2 km. the base is found to
be an intensely hard, gray, small-pebble conglomerate, crammed with
inclusions — some certainly striated — resting through the medium
of a greenish, thin, and variable quartzite on the lower tillite, a break

occurring at this level. This is the band whence most of the specimens

ARGENTINA AND BOLIVIA

in museum collections labeled “tillite” come from, though it is
decidedly not representative.

The zone itself consists of this hard conglomerate, followed by
brownish to greenish quartzites and greywackes possessing feeble
or irregular bedding, with some softer bands allied to tillite. The zone
recalls some of the quartzite bands and lenses in the southern Dwyka,
for example, some near Matjesfontein station in the Southern
Karroo, being in the nature of interglacial sands, while at kilometer
531.75 are some of those curious quartzitic “pseudo-boulders, ” such
as have been recorded from the Cape and Natal, representing masses
of sandy material picked up by the ice and “balled up” during the
progress of the glacier.

The upper part of the glacial series is best seen along the road
from Sierra de la Ventana to Peralta, at a point nearly midway
between the Cerro de Pillahuinco and the Cerro Bonete. Here the
tillite (4C) becomes finer grained and more cleaved, inclusions get
isolated, smaller, and at length fail entirely, and the rock passes up
without a break into a zone (5) about 100 meters thick, of hard,
cleaved slates of blue-gray color characterized by little ocherous
concretions due to the oxidation of pyrite or marcasite, and these in
turn into the group of sandstones, greywackes, flagstones, and quartz¬
ites (1 6 ) building the Cerro Bonete and the hills to the northeast and
north, which can for convenience be termed the “Pillahuinco beds. ”

(c) The Strata of the Sierra de Pillahuinco — This is the only point
in this neighborhood where I found the exposures sufficiently good to
show the passage between the glacials and the group building the
Sierra de Pillahuinco, the age of which has hitherto been in doubt. It
is true that Keidel recorded the superposition of the latter upon the
tillite at one point, which, however, he took to be due to thrusting,
as is not at all unlikely, for in the range lying a few kilometers to
the northwest from kilometer post 529 the arenaceous zone near the
base of the Pillahuinco beds seems to be thrown against the tillite
by faulting.

The strata that were studied between the Cerro Bonete and
Peralta station consist of hard gray-green sandstones and quartzites,
pale in the coarser and generally darker in the finer-grained vari¬
eties ; there are also schistose greywackes and some thinner shaly and
flaggy bands still displaying cleavage, but the strata as a whole are
very different from the Devono-Carboniferous succession to the
southwest. To the east of the railway, Keidel has recorded red and
green slaty beds, often blotchy, and beds of clayey limestone and
marl similar to those observed by Schiller on the northern edge of
the Sierra de Pillahuinco, north of Peralta, intercalated with the
quartzites — probably higher zones within the series.

The folding in the Cerro Bonete is gentle, but, followed north-

26 GEOLOGICAL COMPARISON OF SOUTH AMERICA WITH SOUTH AFRICA

eastward, it becomes more intense. While asymmetrical there, as is
also the case just northwest of the railway, on proceeding northward
the folds, as Keidel has remarked, become overturned to the south¬
west, though it is important to observe that the crumpling after¬
wards decreases and that opposite Stegmann Station (507 km.) the
beds are now practically flat. The fact that the pre-Devonian strata
of the Sierra de Tandil are so little disturbed indicates that the
“ Gondwanides ” must be fading out towards the northeast.

The parallel is extraordinarily good with the Ecca series of the
southwestern Cape, say between Laingsburg and Prince Albert, where
the foldings die out in a northerly direction within a relatively short
distance. The southern Ecca, moreover, contains thick groups of
hard grayish and dark greenish sandstones, almost a quartzite in
places, and much flagstone in addition to hard green and purple mud¬
stones and shales and sometimes impure limestones. The unfossil-
iferous nature of the Cape beds is another parallel, for in the brief
search possible near Peralta only worm castings were seen and some
poor impressions that might be parts of plants. A further examina¬
tion of these beds is hence extremely desirable. In the corresponding
portion of the Lafonian system of the Falklands, Baker has also
recorded fine-grained and intensely hard greenish sandstones, and
sometimes typical slates. It should be noted that the carbonaceous
shales of the Dwyka or of the Iraty series do not appear to be repre¬
sented, but they are certainly missing in the Falklands and probably
too in the district of San Juan to the northwest.

id) The High-Level Gravels — To my mind the most striking par¬
allel with the Cape is formed by the consolidated gravels and breccias
resting on benches or terraces cut along the inner side of the quartz¬
ite chain of the Sierra de la Ventana (Plate III, A). Indeed, viewed
even at short range, I had great difficulty in realizing that this was
another continent and not some portion of one of the southern
districts in the Cape, say Caledon, Oudtshoorn, or Uniondale. Taken
in conjunction with the other resemblances already mentioned, the
parallelism is so wonderfully close that one can not escape from the
conclusion that the geological histories of these two countries
must have been all but identical from mid-Palaeozoic down to
early Tertiary.

As Keidel 33 has so well described, and exactly as in the Cape, the
highest terrace is merely a shelf incised in the quartzites beneath the
crest of the range, running at a level of close on 800 meters above the
ocean. The second has an altitude varying between 450 and 550
meters, cut at about the junction of the quartzites and the younger
slates, and evidently had a wide distribution formerly, since the
spurs of slates and greywackes between the valleys leading down to

33 Keidel (1916), pp. 37-42.

ARGENTINA AND BOLIVIA

the Rio Sauce Grande show all the characters of a dissected peneplain
transecting the highly tilted Palaeozoics and sloping from the range
gently toward the northeast. In places this terrace still bears cap¬
pings of hard, bright-red conglomerates and breccias, as, for example,
at the head of the Arroyo San Bernardino below the Tres Picos (Fig.
i , 7) where the deposit is composed chiefly of subrounded to angular
lumps of quartzite coarsely stratified and set in a hard arenaceous
cement colored with oxides of iron. The material resembles exactly
in its character and habit the so-called “high-level gravels” or
“ferricretes” of the southern Cape; comparison might be made
between Keidel’s Plates IX and X and Plates XXIII and XXIV
in Rogers and Du Toit’s Geology of Cape Colony.

Obviously these are terrestrial scree and gravel deposits, which,
from analogy with South Africa, were formed on a peneplain carved
out during the early part of the Tertiary, and which in similar fashion
have since been dissected to a depth of from 100 to 200 meters, as
marked by accumulations of boulders or by patches of younger
gravels at various levels in the valleys. This in the Cape was due to
the elevation of the interior of the continent in about the Miocene or
Pliocene. In Argentina, however, this broken country subsequently
became in great part buried beneath the mantle of Pampean loess.

Attention might be drawn to the fact that in the neighborhood of
Bahia Blanca borings have disclosed at a depth of about 600 meters
beneath marine (probably lower) Tertiary a group of red clays and
grey and white marls sloping gently to the southeast, which, although
unfossiliferous, are regarded as upper Cretaceous from their resem¬
blance to strata of that age developed in Patagonia.34

SECTION F. THE SOUTHERN PRE-CORD 1LLERAN REGION

As Windhausen 35 has pointed out, the fold-belt of the area just
described is doubtless prolonged to the northwest beneath the Pam¬
pean formation, curving somewhat toward the north in that direc¬
tion, for Gondwana beds appear from below Pleistocene basalts and
Triassic volcanics in the Sierra Pintada near San Rafael on the Rio
Atuel, where they exhibit a north-northwesterly strike.

Unfortunately, very little is known about this rather important
inlier, though Windhausen has mentioned the presence of a tillite and
also an unconformity at the base of the Gondwana beds, but the
intensity of the erosion that followed the late Permian foldings is
indicated by the unconformity between these and the succeeding
Triassic quartz-porphyries and tuffs.36

It would appear that the “ Gondwanides ” — the “Hercynian
folds” of Groeber — extend northward into Mendoza and San Juan;

34 Wichmann (1918). 36 Windhausen, p. 35; Groeber (1918), p. 53.

35 Windhausen (1918), p. 35.

28 GEOLOGICAL COMPARISON OP SOUTH AMERICA WITH SOUTH AFRICA

but in that direction the strata have subsequently become involved
in the younger Andine movements with a north-south strike and are
much affected by overturning and thrusting, whereby slices of differ¬
ent formations down to the Tertiary have repeatedly been brought
into abnormal relationships with one another and the continuity of
the relatively narrow belts of Gondwana frequently interrupted.
The earlier north-northwesterly directed flexures can nevertheless
still be made out in parts of San Juan and Jachal. Throughout this
region the Gondwana, known as the “Paganzo, ” rests unconforma-
bly upon the Devonian or upon older formations.

(1) The Glacial Beds of San Juan and Jachal

At the foot of the Sierra Chica de Zonda, to the south of the town
of San Juan, various strata have, through the labors of Stappenbeck,
Bodenbender, and Keidel,37 long been known to crop out, containing
examples not only of Carboniferous plants, but of the Glossopteris
flora, and also glacial beds. It becomes important, therefore, to con¬
sider the precise relationships of the formations involved, in view
particularly of the opinion expressed by Keidel that there are two
distinct plant-bearing groups, the one pre-Gondwana with European
Carboniferous forms, the other overlying the glacials and considered
as of “Permian” age. It will accordingly be instructive to describe
in some detail the certain sections that I visited at the foot of this
great range some 25 km. to the south of San Juan, where the relation¬
ship of the plant-bearing zone to the glacials is beyond all question.
The area examined is a few kilometers long, extending from a point
a little to the Rio Grande down to the Rio de la Mina, as shown in the
sketch map (Fig. 2).

The Sierra consists of a lofty barrier of gray-weathering Ordo¬
vician limestones and along its eastern base extends a group of highly
tilted green slates and greywackes, with some thin fossiliferous lime¬
stones, presumably of Silurian age. The Gondwana beds are exposed
in the foothills and in a number of small ravines, but on leaving the
slopes their outcrops soon become hidden beneath deposits of boul¬
ders and gravels. Good exposures are found of the basal beds, but the
outcrops of the higher groups are limited and sometimes isolated.
Piecing together the various sections, which can be done without
much uncertainty, there is discovered a thickness of about 360 meters
of the Gondwana, or, as they have customarily been termed, ‘ ‘ Pagan-
zo” beds, resting unconformably upon the Lower Palaeozoic and
dipping eastward below a covering of tilted Calchaquenos (Tertiary)
and nearly horizontal Quaternary gravels.

The Gondwana embraces three distinct glacial horizons , one of
which forms the very base of the system, while the intercalated sedi-

17 Stappenbeck (1910); Keidel (1922).

ARGENTINA AND BOLIVIA

ments between that and the second horizon yielded plant remains,
among which were the Carboniferous genera Cardiopteris and Rha-

Fig. 2 — Geological sketch-map of a small area along the eastern base of the
Sierra Chica de Zonda to the south of San Juan. OS, Ordovician and
Silurian limestones and shales. 1-7 Paganzo system: 1, first glacial zone;
2, plant-bearing shales and sandstones; 3, second glacial zone; 4, sand¬
stones; 5, third glacial zone; 6, shales with some sandstones; 7, red and
dark shales. C, Calchaquenos and Quaternary gravels.

copteris , but no marine fossils. The discovery of these forms, taken in
conjunction with the other plants found in this locality by previous
workers, tends to invalidate Keidel’s argument for the existence of

30 GEOLOGICAL COMPARISON OF SOUTH AMERICA WITH SOUTH AFRICA

two distinct formations, one with Carboniferous plants older than
the Paganzo, the other having glacials and containing the Glossop-
teris flora. For this reason it does not become necessary to make use
of the two-fold division made by him into the “Jejenes” and the
“Zonda” series, nor need the supposed relationship of these series be
argued. In only this respect do the very valuable observations and
conclusions of Keidel need to be modified, though unfortunately it
will affect his criticisms of the writings of Bodenbender, Hausen,
Penck, and others.

In the small ravine o. 5 km. north of the Rio Grande the base of the
Gondwana is excellently exposed, the first glacial zone (Plate III, B)
from 8 to 20 meters thick, resting upon an uneven surface of highly
tilted slates (A) and limestones (B) (Fig. 3). At the point X the
floor is actually vertical, and in the pocket below it lies true ground

Fig. 3 — -Section, about 75 meters in height, in ravine north of the Rio Grande,
Sierra Chica de Zonda. For explanation, see text.

moraine (a), above which comes a thin, curving layer of green fissile
shale ( b ) with annelid or crustacean markings, which laps over the
limestone band (B), the top of which is nevertheless polished and
striated, the groovings (Plate IV, A), after making due allowance for
the subsequent tilting, being directed north-northwest- south-
southeast. The overlying glacials (c) range from a true, unbedded
tillite of normal character to a stratified fluvio-glacial conglomerate
having the inclusions lying with their longer axes parallel to the
stratification, though striated boulders are common. They pass up
into, or to some extent are even interlaminated with, dark carbon¬
aceous shales and micaceous flagstones and thin sandstones with
occasional plant remains (d), grading up into a group of flagstones
(e) and yellowish-gray sandstones (/), sometimes micaceous, getting
coarser toward the summit, the succession being clearly shown in
Plate IV, B.

At a height of about 165 meters above the base the second glacial
zone makes its appearance (Plate V, A). In the neighboring Rio de

ARGENTINA AND BOLIVIA

Jejenes, on the southern side of the ravine (Plate V, B) , its base is sharp,
the band incloses lenses of sandy stuff as shown in the nearby view
(Plate VI) , and the inclusions are as a rule small and of hard rock,
though one of them, composed of gneiss and resting directly upon
the sandstone, constituting the floor, is nearly 3 meters in diameter.
The succession, it might be remarked, is a perfectly conformable one.
In the lower ground to the east, where this zone is proceeding to dis¬
appear beneath higher beds, it is nearly 50 meters thick, composed
of a lower group of fliivio-glacial sandstones and tills and a thin bed
of shale above, passing up through boulder-shale into tillite (Plate
VII, A) ; finely striated erratics can readily be picked up. An example
has been figured by Coleman and it is hence unnecessary to give any
additional illustrations.

The top passes through pebbly grit and sandstone into greenish
shaly beds, in which at 50 meters there appears boulder-shale, and
next the third glacial zone, about 12 meters thick, overlain by more
hard, greenish shales, and these, as seen to the south in the channel of
the Rio de la Mina, by alternations of sandstone and shale, with a thin
zone of soft black carbonaceous shales constituting the highest strata
visible. Although so thin, this upper tillite carries some exceptionally
large inclusions, mainly of Ordovician limestone, one slab of which,
a couple of meters in length, contained several large coiled cephalo-
pods. The conspicuous green coloring in some of the beds, absent
in the region to the northeast, serves to link this formation with
the equivalent Pillahuinco beds of the Sierra de la Ventana.

In this terrain, crossing the Rio Grande and the Agua de Jejenes,
the beds are dipping regularly eastward and are not dislocated,
there can not be the slightest doubt that the sequence is a normal
upward one which is resting unconformably upon the Silurian and is
embracing Paganzo beds only. Great weight, therefore, must be
attached to this section, since it provides us with the key to the
Permo-Carboniferous stratigraphy of a very wide region in the pre-
Cordillera, as will be discussed later on.

Proceeding southward in the direction of the Rio de la Mina,
irregularities make their appearance, due partly to the fact that the
floor beneath the system seems to have been highly diversified, and
partly to subsequent tectonic movements, by which anticlinal cores
of Ordovician limestone have been driven through the younger for¬
mation. By such movements, what from their lithological peculiari¬
ties must be regarded as slightly higher zones of the Paganzo, appear
in two fine continuous domes (Plate VII, B), from beneath the folded
unconformable Calchaquenos formation a little to the southwest of
the lime-kilns of Carpinteria not far from the Cerro Bola, a group of
carbonaceous and micaceous shales with nodules carrying plant
remains, soft micaceous sandstones, and reddish mudstones resting

32 GEOLOGICAL COMPARISON OF SOUTH AMERICA WITH SOUTH AFRICA

seemingly through the medium of a thrust-plane upon a core of Ordo¬
vician limestone ; this has been figured very roughly by Stappenbeck
(1910, p. 36, Fig. 1).

The overshadowing feature of the sections just described is the
direct evidence that they furnish upon the position of the plant¬
bearing horizons in relation to the glacials, at the same time proving
the close association of European Carboniferous plant forms with
members of the Glossopteris flora, thereby bringing the succession
into harmony with the sequences observed more to the north and
northeast in the Sierra Umango, Sierra Villa Union, Sierra de los
Llanos, etc., namely, near the base of the Paganzo system, as will be
discussed later.

Seemingly the glacials are represented at intervals along the base
or flanks of this range, . as, for example, in the Cuesta de Pedemal
farther to the south, where Stappenbeck38 reported thick conglomer¬
ates overlain by beds with a “Culm flora” resting upon the Silurian;
but this and other cases require to be reexamined in the light of the
sections described from near Rio Grande.

Working southward from this “type” region, mention has to be
made of the fine section on the northwestern side of the Cerro Pelado
between Mendoza and Uspallata, where, according to Stappenbeck 39
the Paganzo, thrown down against Ordovician limestones and
dipping southeastward at a pretty high angle, has a development of
basal conglomerate, stated by Keidel to be glacial in its nature, rest¬
ing on presumed Devonian and followed by conglomerates, arkoses,
sandstones, shales, bituminous shales, and impure coals from which
Sigillaria , Annularia, and Gangamopteris have been collected. This
section is of further interest in that here and also at Villa Vicenze
toward the north these beds, according to Keidel,40 are overlain with
strong unconformity by the sediments and volcanics of the upper
Triassic.

The mention by Windhausen41 of the “Permian” glacial con¬
glomerate resting unconformably on older beds near San Rafael to
the south in the curious Sierra Pintada with its northwest-southeast
trend is important, as such would indicate a link between the glacials
of the Sierra de la Ventana and those of the Mendoza district.

In the museum of the Geological Survey at Buenos Aires stands
a photograph of an exposure of a tillite labeled “Arroyo del Chiquero,
High Cordillera, Mendoza,” which apparently refers to outcrops at
the base of the Sierra de Tigre, some 40 km. to the northwest of
Uspallata. This helps to connect with the important occurrence
recorded by Keidel at Leoncito Encima in the same valley further to
the north, 25 Ion. distant from Barreal and with that at the Quebrada

38 Stappenbeck (1910), p. 36.

39 Stappenbeck (1910), p. 51 and Fig. 2.

40 Verbal communication.

41 Windhausen (1918), p. 35.

ARGENTINA AND BOLIVIA

del Salto immediately to the east of the latter village, referred to by
Stappenbeck,42 though he did not then realize the glacial character of
the basement conglomerate. Compared with the succession in the
Sierra Chica de Zonda these two occurrences are outstanding, because
the presence of marine fossils in them indicates that within a length
of 45 km., though appreciably greater distance when the effect of
folding has been allowed for, the formation has changed in character
from continental to marine ; it has now been termed the Tontal series.

In the Arroyo de Cabeceras, about 3 km. above the homestead of
Leoncito Encima, I discovered the tillite folded in with the pre-

Fig. 4 — An infolded patch (stippled) of tillite in Palaeozoic beds close to

Leoncito Encima, Barreal.

sumed Devonian slates and greywackes in an extraordinary fashion,
as showm in Figure 4, a feature due to the superposition of the pre¬
vailing north-south crumplings of the pre-Cordillera upon a pre¬
sumably older northwest-southeast folding. The base of the tillite
transgresses across the strike of the supporting Palaeozoics and the
unconformable contact can clearly be made out at several points,
where the surface below, when visible, is polished and shows striae
directed north-northwest-south-southeast (making allowance for
the considerable subsequent tilting of the floor) and which are not
strictly parallel, as in slickensided faces, but cross one another at a
very acute angle in the manner characteristic of glacial pavements.
The tillite is dark green, fine-grained, with small inclusions, rarely
more than 15 cm. in diameter, many of them being finely striated;

42 Stappenbeck (1910), p. 46.

34 GEOLOGICAL COMPARISON OF SOUTH AMERICA WITH SOUTH AFRICA

a rude bedding is present in places, brought out by some banded and
more quartzitic layers. The thickness preserved in this narrow ravine
would not be more than about 30 meters.

About 150 meters distant from the homestead of Leoncito Encima
is the outlier mentioned by Keidel.43 Lack of time unfortunately
prevented any detailed examination of either the base or the topmost
beds, but some sandstones and thin shales were observed overlain by
tillite, and the latter in turn by gritty sandstone with pebbles, fol¬
lowed by fluvio-glacial cong^merates. Important was the presence
of some particularly fine “boulder pavements” of the kind recorded
in the Sierra de la Vent ana, with erratics exposed on the curving,
ploughed-up surfaces, showing good striae directed north-northwest
and therefore in full agreement with the evidence obtained higher up
the valley, as well as in the Sierra Chica de Zonda. Fossils were
collected here by Keidel either as casts or in nodules of clayey lime¬
stone, principally of brachiopods such as Spirifer, Dielasma, etc., but
not specifically determined by him, though he has noted forms resem¬
bling Spirifer alatus and S. rugulatus, suggestive of the Permian;44
Productus was absent. Whether these beds at Leoncito Encima are
really Permian, as supposed by Keidel, or Carboniferous like those at
Barreal, to be described below, can only be decided by the working
out of these fossils.

I was unable to trace the glacials continuously northward, but
feel fairly confident that it must be the same formation that is laid
bare immediately to the east of Barreal, in the Quebrada del Salto,
the beds being finely sectioned by a small ravine a kilometer to the
south of the latter, this dry watercourse rising in an anticlinal valley
scooped out of shales overlying the tillite and hemmed in by a ring
of hard gray and speckled quartzitic sandstones, thin-bedded red
flagstones, gray and bluish siliceous shales, and some soft dark shales
(Plate VIII, A). The tillite is greenish and homogeneous, passing by
degrees through sandy mudstones into olive shales with occasional
small pebbles, and from these into olive sandy shales without inclu¬
sions. Not more than 25 meters of glacial material was exposed at
this spot, with the base not visible, though not improbably a search
to the south would disclose its floor.

Fossils occur not only in the overlying shales in profusion, but
less abundantly in the mudstones with erratics, though absent from
the tillite proper. Spirifer , Productus , Pseudamusium , and Spiriferina
are common, while Polypora and Fenestella are conspicuous low down
in the mudstones, thus duplicating the features seen in the lower
marine series of the Hunter River region of New South Wales, with
its glacial erratics and abundant polyzoa.

Some 150 to 200 meters above this fossiliferous zone, exposed

43 Keidel (1922), p. 256. 44 p. 334.

ARGENTINA AND BOLIVIA

close by and just to the north in the Quebrada del Salto, is another
horizon of dark, reddish weathering, sandy shales from which numer¬
ous mollusca were collected ; this must be the locality discovered by
Stappenbeck,45 from which he obtained a fauna with Spirifer supra-
mosquensis Nik., etc, correctly regarded by him as of upper Carbon¬
iferous age. Some higher beds of hard sandstones and shales follow,
covered up by Calchaquenos to the north, while on the east the suc¬
cession ends by faulting against “Rhaetic” beds.

The forms collected from these two horizons are fully discussed
by Dr. Cowper Reed in the Appendix, and it will suffice therefore to
quote his important decision that these Barreal faunas can without
hesitation be ascribed to the Carboniferous and probably to the base
of the upper Carboniferous. The tillite should belong, then, to about
the border-line between the Moscovian and theUralian, that is to say,
between the Westphalian and the Stephanian, wherefore it has to be
concluded that this succession near Barreal must be the marine
equivalent of the glacials with their plant-bearing zone of the Paganzo
system of the Sierra Chica de Zonda. Phases transitional between
them will now have to be sought for in the intermediate belts of
Paganzo mapped by Stappenbeck 46 in the Sierra Alta de Zonda and
on the western side of the Paramillo de Tontal, where, as recorded by
him, conglomerates, arkose, green and reddish slates, and sandstones
rest on “Devonian” greywackes.

Further to the north towards Jachal, illuminating sections have
been recorded by Stappenbeck and in more detail by Keidel.47 For
example, fluvio-glacial beds are mentioned by the latter as resting
with slight discordance upon a thick group of unfossiliferous though
post-Devonian greywackes in the Quebrada de Talacasto (lat. 310).
In the Lomas de los Piojos, a little to the south of Jachal, reposing
unconformably on the lower Devonian with Leptocoelia flabellites or
on upper Silurian beds, is a tillite passing up into fluvio-glacial con¬
glomerates and these into sandstones with occasional boulders, the
whole possessing a thickness of from 50 to 60 meters. At one spot
Keidel48 found the morainic matter resting upon a well-striated
pavement of fossiliferous Devonian sandstones with the groov¬
ings directed northwest-southeast (see his Plate VII, Fig. 2).

Evidence of glacial deposits is forthcoming from the Cerro Fuerte,
to the east of Jachal, and also from farther north, near Guandacol,
similar strata cropping out around the southern end of the Cerro
Villa Union and the Sierra de Umango, being well seen, for example,
on the western side of the Cerro Guandacol, as described by Boden-
bender and Hausen,49 the latter recording a coarse, tillite-like con-

45 Stappenbeck (1910), p. 37.
*6Ibid., p. 43.

47 Keidel (1921).

isIbid., p. 59.

49 Hausen (1921), p. 70.

36 GEOLOGICAL COMPARISON OF SOUTH AMERICA WITH SOUTH AFRICA

glomerate at the base, followed, but overlapped, by sandstones and
shales and by much younger stages of the Paganzo, including beds of
Rhaetic age. More detailed reference to these last and to their equiv¬
alents in the ranges more to the east, e.g., the Sierra de Sahogasta,
Sierra del Valle Fertil, and Nevada de Famatina, will be made later.
Undoubted glacials have not yet been recorded to the east and north¬
east of the last named, barring Penck’s assertion of an unbedded
tillite-like formation close to Angulos on the eastern side of the chain.
Instructive is his discovery in the Puna de Atacama of Cardiopteris
polymorpha in coaly shales resting on the conglomeratic sandstones of
the lowest division of the Paganzo, as in San Juan, while intercalated
basaltic flows are also present.

(2) The Plant-bearing Beds and Their Age

Though this discussion might more appropriately follow the
succeeding account of the Paganzo system, it is most conveniently
introduced here in order to demonstrate the close relation of the
fossiliferous bands to the glacial horizons of the Sierra Chica de
Zonda.

In the course of a brief search in the Rio Grande I obtained from
the carbonaceous shales (dt Fig. 3) between the first and second
glacial horizon and about 50 meters above the base of the system,
specimens of Cardiopteris polymorpha and Rhacopteris szajnochai ,
while Bodenbender 50 collected (almost certainly from this band,
which is to be found cropping out again in the next ravine nearby,
that of the Arroyo de Jejenes) Rhacopteris szajnochai , and in addition
Gangamopteris cyclopteroides , Glossopteris browniana, Cordaites , species
of Sphenopteris , and fragments of a fish, Rhadinichthys argentinus
Tornq. So far as I can make out, just a little to the north of the Rio
Grande and west of Paradero kilometer 489 is Rinconada, whence
Bodenbender gathered Cardiopteris polymorpha , Adiantites antiquus ,
Neuropteridium validum , and species of Sphenopteris . Some 5 km.
south of Jejenes and to the west of Carpinterla he also discovered
Glossopteris ampla , presumably in the same beds as Bergiopteris
insignis , Lepidodendron cf. australe, and Asterocalamites scrobiculatus ,
while beyond at Retamito, in the Quebrada del Agua, in beds over-
lying thick conglomerates — not improbably glacials — resting upon
the Silurian, Bodenbender found Rhacopteris sp., Botrychiopsis
weissiana , Asterocalamites scrobiculatus , Lepidodendron pedroanum,
L. australe , L. cf. notlium , and Cordaites sp. Kurtz 51 has described
several other forms from these several localities, such as Rhacopteris
inequilatera , var. ovata, Archceopteris argentine , and Cardiopteris
elegans.

60 Bodenbender (1902), p. 203, (1911), p. 86; Stappenbeck (1910), p. 40.

61 Kurtz (1921-22).

ARGENTINA AND BOLIVIA

More to the south, in bituminous shales above the glacials of the
Cerro Pelado, Gangamopteris is associated with Sigillaria and Aster o-
calamites. Traveling northward, one finds at Trapiche,62 between
Jachal and Guandacol, Cardiopteris polymorpha, with Lepidodendron
(. Lepidophloios ) laricinus , Cordaites hislopi, and Neuropteridium
validum, the latter also at Cerro Bola, a little to the east, and at Sano-
gasta, while in the Cuesta Colorada (Escala de Famatina) Rhacop-
teris inequilatera has been gathered. Penck 53 has reported the finding
in the Puerta de Guanchin in the Puna de Atacama, of Cardiopteris
polymorpha , Botrychiopsis weissiana, Phyllotheca australis , and
Gingkophyllum grasseti in clay shales and thin impure coals overlying
the basal conglomerate, here 22 meters thick. In the Sierra de Vilgo
at the Cuesta de la Torre, Lepidodendron aculeatum occurs low down
in stage I of the Paganzo. At Saladillo,54 near the southern end of
the Sierra del Velasco, black shales have yielded Lepidodendron selagi-
noides and L. veltheimianum . On the other hand, proceeding south¬
eastward into the Sierra de los Llanos, we have recorded from the
Arroyo Totoral and elsewhere Neuropteridium validum, Cordaites
hislopi , Glossopteris retifera, G. indica , Phyllotheca deliquescens , and
other forms, while at Bajo de Velis,55 in the Sierra de San Luis farther
to the south, has been obtained the well-known assemblage including
Neuropteridium validum , Gangamopteris cyclopteroides , Cordaites
hislopi, Noeggerathiopsis whittiana, Rhipidopsis densinervis, R.
ginkgoides, etc.

Keidel 56 has been to great pains in order to prove that there are
actually two distinct series resting unconformably upon the older
Palaeozoics, one with a flora including lower and upper Carboniferous
forms and hence of Carboniferous age, overlain by the second formed
of the glacials and the sediments with the Glossopteris flora, belong¬
ing to the Gondwana system and of “Permian” age.

It must candidly be admitted that the evidence as to the precise
horizons from which these several identified collections were made is
not beyond criticism, and unfortunately my limited opportunity for
collecting did not enable me to dispel such doubts, though the ques¬
tion could very readily be settled. It can nevertheless be affirmed
that along both the Rio Grande and the Arroyo de Jejenes the car¬
bonaceous shales (d, Fig. 3) constitute a zone such as would natur¬
ally be searched by the collector, although not the only fossiliferous
horizon present, since the upper part of the sandstone group, /, also
yielded some poorly striated stems. No plants were observed in the
sandstones between the second and third glacial zones and, sugges¬
tively, no strata higher than the latter are represented in those two

52 Bodenbender (1911), pp. 82-83.
63 Penck (1920), p. 146.

M Bodenbender (1911), p. 81.

65 Kurtz (1895).
60 Keidel (1922).

38 GEOLOGICAL COMPARISON OF SOUTH AMERICA WITH SOUTH AFRICA

localities. To the south, however, along the Rio de la Mina, plant
fragments were noticed in shaly sandstones between 30 and 40 meters
above the third glacial zone.

It would consequently seem most likely that Bodenbender’s
specimens mentioned above from the Arroyo de Jejenes came from
the strata lying between the first and second glacial zones. Boden-
bender, Kurtz, and others nowhere remark that the plants collected
by them in any one locality near the base of the Sierra Chica de
Zonda were actually derived from distinct horizons, wherefore, until
more careful collecting has been carried out, we can only assume that
each lot was obtained from some stratigraphical unit rather than
from several horizons a good distance apart.

In analyzing these various collections, we observe further that in
one locality or another some typical member of the “northern flora’ ’
is in apparent association with some member of the “southern, ” and
this in so many ways that we have difficulty in escaping from the
conclusion that all these various plants must probably have occurred
intermingled on horizons intimately associated with the glacial
series. It will, however, not be denied that the southern forms might
perhaps have come from slightly higher levels within that particular
series than those that yielded the northern elements, and it will
therefore be conceded that Gangamopteris , Glossopteris, etc., if not
actually accompanying Rhacopteris, Cardiopteris , etc., must occur
shortly above this lowest plant-bearing carbonaceous zone d , with
its northern Carboniferous flora. A search should enable this highly
important palaeobotanical relationship to be definitely established.

Granted that the data have been correctly interpreted, the pres¬
ence of Gangamopteris, Glossopteris , Neuropteridium, etc., would
suggest that the whole of this definitely conformable succession,
down to its very base, resting discordantly upon pre-Carboniferous
strata, should be regarded as forming part and parcel of the Gond-
wana system. In this conclusion I find myself in accord with Boden-
bender, Stappenbeck, and Penck. The sections on the Rfo Grande
and Arroyo de Jejenes are particularly clear, and, while some uncer¬
tainty attaches to the precise levels from which many of the plants
have been collected, the interpretation here advanced does not seem
to me to do violence to the facts.

It is most suggestive that in the chain of outcrops from the Cerro
Pelado due northward to the Puna de Atacama and eastward into
Famatina, the bulk of the plants appear to have been found in a zone
of carbonaceous shales with occasional thin layers of impure coal
that lies not far above the basal conglomerates and arkoses, beds
largely of glacial origin. From the section in the Sierra Chica de
Zonda it is clear that this zone (d, Fig. 3) is overlain by glacials as
well, but how far the latter extend northward is a matter for future

ARGENTINA AND BOLIVIA

investigation. It is precisely, too, in this western section of Argen¬
tina, that the northern plant forms with a Carboniferous aspect
are to be found, and they most decidedly indicate an age for the
inclosing strata not younger than upper Carboniferous ( Stephanian or
Pennsylvanian) , possibly even the top of the middle Carboniferous.

On the other hand, Bodenbender 57 is quite definite that in the
region eastward, Sierra de Velasco, Sierra de los Llanos, etc., the
plant-bearing beds are of similar lithological character and are all
more or less on the same particular horizon, within Stage I, seemingly
in its upper half, and hence apparently on a slightly higher level than
in the west. It is significant too, that in the east the records of
northern plant forms all but fail, but that Lepidodendron aculeatum
occurs in the Cerro de Vilgo lower down than is usual, while near
Cerro Bola in the west Cordaites hislopi and Neuropteridium validum
are represented near the top of the group. Taken in conjunction
with the fact that some carbonaceous shales also occur in the Sierra
Chica de Zonda some distance above the third glacial horizon, there
is a definitely proved stratigraphical overlapping toward the east
(referred to below) , causing higher zones to come to rest on the ancient
rocks, it would seem that in the west lower horizons may generally be
represented, which tend to be missing in the east. This view is sup¬
ported by the triple development of the glacials in the west and their
absence, or perhaps their non-record, in the east. The first mentioned
condition is certainly the case at Bajo de Velis, where I was able
to examine the base of the Paganzo, for the beds with Gangam -
opteris rest directly on schists without the intervention of a glacial
conglomerate.

Some remarks are needed regarding the plants themselves as
indicators of age. The determinations were all made by Kurtz,58 and
in a number of cases no descriptions were published, though recently
a few have posthumously appeared,59 in most cases, however, unac¬
companied by figures. I consequently have found it difficult to
criticize the determinations, while, when in Cordoba, I had only time
to examine the extensive collection of Rhastic plants in the museum
of the university.

It might be remarked at the outset that the majority of the mem¬
bers of the Glossopteris flora are of little or no value in establishing the
absolute age of the beds. Recent work has been showing more and
more that certain genera and species thereof had a long range in
time and these sections in Argentina are of immense importance,
therefore, in demonstrating that Gangamopteris cyclopteroides , Glos¬
sopteris browniana, and Cordaites hislopi extend back well into the
Carboniferous, as also appears to be the case in New South Wales.

67 Bodenbender (i9ii),p. 83.

68 Kurtz (18950); Bodenbender (1904), (191 1).

69 Kurtz (1921-22).

40 GEOLOGICAL COMPARISON OF SOUTH AMERICA WITH SOUTH AFRICA

Of the undoubted “northern” forms, Asterocalamites scrobicu-
latus (Schloth), described originally in 1894-95 by Kurtz as Archx-
ocalamites radiatus , is found in Europe and North America, being
sometimes known as Bornia scrobiculata Stern, extending up into
the lower part of the upper Carboniferous (Pennsylvanian) , but has
been recorded by Walkom under the name of Archxocalamites scro-
biculatus from Queensland, together with Glossopteris and Cordaites,
the only other country in which this remarkable association has yet
been recorded. Adiantites is a genus with a similar range, but from
Kurtz’s meager description thereof and the absence of a figure, direct
comparison with the Culm species A . antiquus (Ett) is not possible.
Archxopteris argentinx Kurtz is compared by him with A . wilkinsoni
Feist, from New South Wales, while with Archxopteris obtusa Lesq.,
from the Pennsylvanian, Kurtz compares his Bergiopteris insignis.
Botrychiopsis weissiana Kurtz, with Cardiopteris- like pinnules,
appears to be intermediate between Cardiopteris and Neuropteris.

Cardiopteris polymorpha (Goepp) is a lower Carboniferous form
and does not seem to be known from the upper division ; an undeter¬
mined species comes from the Kuttung series (middle Carboniferous)
of New South Wales. C. elegans Kurtz stands close to C. polymorpha .
Rhacopteris inequilatera (Goepp) has been referred by Dun to
Aneimites ( Otopteris ) ovata (McCoy), with which Kurtz has placed
R. inequilatera var. ovata from Jejenes, including also A. austrina
Eth., the last from the Drummond series of Queensland, the first
named from the Kuttung series of New South Wales, which contains
other species of Rhacopteris. Lepidodendron veltheimianum is a lower
Carboniferous species, while L. pedroanum occurs in the Bonito group
of Brazil. The Sphenopterids may be upper Carboniferous forms,
but only one has been figured.60

It might be remarked that the only records of such Palaeozoic
plants are from Lake Titicaca in Bolivia and from Paracas on the
coast of Peru by Seward 61 and Berry.62 No specific names are given
by the former, but his Sphenopteris sp. recalls, however, S. boden-
benderi Kurtz, but appears to agree better with the description given
of S. fonsecx Kurtz, from Carpinteria, though no figure of the latter
has been published. Berry, however, has identified among others
Lepidodendron rimosum Stem, L. obovatum Stern, Catamites suckowii
Brong., Eremopteris whitei Berry, and E. peruiana Berry. He regards
the flora as probably Westphalian (middle Carboniferous) and points
out that on Lake Titicaca at least one of these forms occurs in strata
underlying the marine upper Carboniferous (Uralian).

In spite of some uncertainties in the identifications and the
necessity of revision, there can be no doubt that the northern ele-

60 Kurtz (1921-22), PI. XIV, Nos. 138, 138a, and 139. 62 Berry (1922).

61 Seward (1922).

ARGENTINA AND BOLIVIA

ments in this western Argentine flora definitely place it on about the
border line of the middle and upper Carboniferous. So far back as 1895
Kurtz correctly pointed out this fact and also drew attention to the
parallelism with the plant-bearing Carboniferous beds of New
South Wales and Queensland. The discovery of associated glacials
both in San Juan and in the Seaham area of New South Wales
strengthens this comparison enormously. The floras of the lowermost
Paganzo and of the Kuttung 63 series of New South Wales have strong
resemblances, and in each case, and also in Peru, there is the com¬
plete absence of species of the common Neuropteris , Pecopteris, and
Alethopteris groups, all of which become very abundant in the typical
middle and upper Carboniferous floras in various parts of the world.
The presence of the Glossopteris flora and its absence from the Kut¬
tung, so far as we know, suggest an age slightly younger than that
of the latter for the lowermost beds in Argentina, which would
place them at about the beginning of the upper Carboniferous
(Pennsylvanian) .

The flora of the beds situated to the east of San Juan, with its
paucity of Northern forms, can be compared with that of the lower
marine series of New South Wales that immediately follow the
Kuttung, or the Queensland ‘ ‘ Permo-Carboniferous ’ ’ with species of
Glossopteris, Sphenophyllum, Cordaites, and Sphenopteris. Just as in
the Hunter River area glacial conditions recurred, so was the case in
San Juan, where the basal glacials and lowermost plant-bearing
group were succeeded by more morainic matter, all, however, still of
Carboniferous age.

This strong parallel between Argentina and the eastern side of
Australia must be emphasized, since under the displacement hy¬
pothesis the space separating these two regions would at this epoch
have been enormously less. This question wx>uld, consequently,
appear to be worthy of examination from other viewpoints in the
light of this hypothesis.

(3) The Name “Paganzo System”

Thus far attention has been focussed almost wholly upon the
basal portion of the system as developed in that section of the pre-
Cordillera from Mendoza northward into La Rioja with the object,
firstly, of bringing out the evidence for the existence of glacial
deposits, as in other parts of Gondwanaland, and, secondly, of show¬
ing that certain of the scattered florules are actually sandwiched
between glacial horizons. Before reviewing the information available
regarding these and the still higher strata that are so extensively
developed in the region to the east and northeast — not only in the
pre-Cordillera, but in the central or Pampean ranges as well — some

63 Siissmilch and David (1920).

42 GEOLOGICAL COMPARISON OF SOUTH AMERICA WITH SOUTH AFRICA

discussion becomes necessary upon the limits to be set to the
“Paganzo beds. ”

This name was given by Bodenbender 64 from the village of Pagan -
zo to the south-southwest of La Rioja, where the several stages or
divisions of this important group of strata are so well developed, but
from which the so-called “Rhastic ” beds were definitely excluded. It
is true that Keidel65 subsequently adopted a new classification, the
‘ ‘ La Rioja system, ” a course in which he was doubtless influenced by
his separation of the basement strata in San Juan into the two series
of “ Jejenes ” and “Zonda. ” Now that it has been shown that such a
division is scarcely necessary, the term “La Rioja system” becomes
superfluous and there would be no genuine grounds for superseding
the original and well-established term “Paganzo, ” which has so firm
a place in geological literature. On the other hand, the exclusion of
the “Rhaetic” from the Paganzo is wholly indefensible, since, (a)
these younger beds generally include some strata of upper Triassic
age similar in many ways to the older groups of the Gondwana; ( b )
they are non-marine in character; (c) although they are generally
unconformable to the lower stages of the Paganzo, places are known
where no marked break has yet been recorded, or where as yet no
inferior limits can be set to the group ; and (d) they admittedly cor¬
respond with the upper part of the Santa Catherina system of Brazil,
with the Stormberg series of South Africa and with a part of the
middle Gondwana of the type region of India.

As will be realized from the study of the following pages, it would
be difficult to make out any adequate case for the exclusion of these
younger beds, excepting for their general unconformable position,
which relationship, it must be pointed out, is certainly present some¬
where in each of the other sections of Gondwanaland. Since the
strata thus embraced range from Carboniferous to Rhaetic in age, it
is furthermore clear that a mere “series” would be insufficient to
include them — nothing less, indeed, than a “system,” so the Paganzo
must be given a rank equal to the systems of the Santa Catherina,
Karroo, or Gondwana, of which it is the Argentine representative.

In the following pages, therefore, though contrary to practice in
Argentina, the so-called “ Rhaetic ” will he regarded as forming the
uppermost member , i.e.y Stage IV > of the Paganzo system.

(4) The Distribution of the Paganzo

Deposited unconformably upon Palaeozoic and crystalline rocks,
and largely covered by Cretaceous and Tertiaries, these beds
have been involved in the Andine movements, wherefore dips are
often high, inversion may occur, while faulting and thrusting are
common. In consequence, the beds now make their appearance along

65 Keidel (1922), p. 267.

64 Bodenbender (1911), p. 47.

ARGENTINA AND BOLIVIA

the flanks of the various ranges, occupying a position intermediate
between their Palaeozoic or crystalline cores (which generally compose
the mountain mass) and the Cretaceo-Tertiary (which commonly
form the lower ground) , and therefore crop out most usually in the
form of narrow belts, not infrequently obscured over considerable
stretches by late Tertiary beds or by Quaternary gravels and sands.
The clarity of the exposures, due to the broken nature of the ground
and the aridity of these regions, is consequently offset by the fre¬
quency with which the strata are hidden by these younger formations ;
rarely is any wide area to be found occupied by the Paganzo, though
the system doubtless underlies many of the Tertiary-filled valleys
or intermontane plains.

The principal occurrences, as described by Brackebusch,66
Stappenbeck,67 and particularly by Bodenbender,68 are to be found
between the extremity of the Gerro Villa Union and the Sierra del
Valle Fertil, on the western and southern sides of the Sierra de Vilgo
and Sierra de Sanogasta, at the southern end of the Sierra de la
Huerta, around the greater part of the edge of the Sierra de Chepes and
Sierra de los Llanos and in small areas in the Sierra Brava, Sierra de
Cordoba, and at Bajo de Velis in the Sierra de San Luis. To the north¬
west they are represented in the Sierra de Umango and beyond in
the Puna de Atacama up to the border of Bolivia, while to the north¬
east they reappear in Tucuman, Jujuy, and Oran, and thence have a
lengthy distribution far to the north, as will be set forth in section G.
Bore-holes in the northern and northeastern parts of Argentina sug¬
gest that they may occupy a considerable tract beneath the thick
covering of Neogene, possibly even joining up underground with the
known extension of the Santa Catherina system into the territory
west of the lower Parana River.

(5) The Stratigraphy of the Paganzo

The system can be divided into four “ pisos ” or stages , the first of
upper Carboniferous, the second and third of Permian, and the
fourth of Trias-Rhsetic age, though extending probably into the
Liassic, with the very uppermost portion thereof regarded tentatively
as constituting stage V.

Stage I — This generally ranges between 150 and 300 meters in
thickness, though probably well exceeding that value in San Juan,
where, as remarked above, lower horizons would seem to be present.
On the other hand, in certain places it is thin or even absent, owing
to the transgression of higher beds, occasionally even those of stage
II. Thus in the valley of the Rio Nogues to the east of Cerro Villa

66 Brackebusch (1891) and geological map (1892).

67 Stappenbeck (1913, I91?, 1920)-

68 Bodenbender (1897, 1902, 1911, 1912, 1916).

44 GEOLOGICAL COMPARISON OF SOUTH AMERICA WITH SOUTH AFRICA

Union the upper conglomerate, lying just below Stage II, rests on the
crystalline schists, while farther to the east, in the neighborhood of
Sanogasta (Nevado de Famatina), Stage II rests on granite or
quartz-porphyry. Furthermore, in the Puna de Atacama, Penck 69
has observed the red sandstone of Stage III reposing directly upon
granite in the Cerro Negro de los Andes (west of Tinogasta) and
Cerro Palca, more to the north.

In the extreme west there are developed at the base of the system
the glacials detailed earlier, having an intercalated zone with plants
of middle and upper Carboniferous genera and species, but, while
stratified conglomerates (particularly well developed in the Sierra
de los Llanos for example) , arkoses, and gray, yellowish, and greenish
sandstones occur in this inferior position toward the east, Boden-
bender has stated that he had observed no evidences of glaciation in
them. Penck’s note of an unstratified boulder deposit, like a tillite,
close to Angulos, a little north of Famatina, indicates the possible
existence of glacial material in that quarter. At Bajo de Velis
glacials are absent at the bottom of the system.

Not improbably the prevailing conditions are rather like those
that have been made out in South Africa in passing from Natal to
the Transvaal, where, owing to the uneven nature of the (glaciated)
floor and to a temporary “post-glacial” exposure of the latter, coarse
fluviatile sediments have come to overlap on to, and rest upon, the
glaciated land surface, and the morainic deposit is only to be found
preserved in the deeper hollows in the latter.

Above this coarse basal phase in Argentina is a conspicuous zone
of carbonaceous shales with thin coaly streaks and layers, sometimes
pyritic in its nature. It is followed by sandstones (as in the Cerro
Villa Union), by conglomerates with porphyry pebbles, and by means
of a hard white sandstone passes up by degrees and quite conformably
into Stage II. Some calcareous and siliceous concretions are to be
found and also thin beds of limestone in the Sierra de los Llanos.
The carbonaceous zone alluded to is, as Bodenbender 70 has remarked,
a constant feature, and has yielded, as already stated, the Glossopteris
flora at a number of points, e.g., Sierra de los Llanos and Bajo de
Velis (Plate VIII, B), an association strikingly like that of the Bonito
series of Brazil succeeding the Itarare glacial series of that country,
and which, from external evidence very largely, we have to place at
the top of the Carboniferous.

Stage II — Not less than 300 and probably up to 500 meters in
thickness, it is distinguished from the older group by the brilliant
coloring of the beds — rose, red, gray, white, etc. — by clayey, cal¬
careous, and siliceous strata, fine-grained red and partly white sand¬
stones, thin quartzites, and bands of limestone up to some meters

69 Penck (1920), p. 134. 70 Bodenbender (1911), p. 64.

ARGENTINA AND BOLIVIA

thick, and silicified marls. The calcareous matter may occur in the
form of concretions and lenses and is often dolomitic ; partial silicifi-
cation has caused the strata (particularly in the middle of the group)
to resemble on weathering mottled felsites, while oolitic structure is
common; especially is this the case in La Rioja, though this phase is
not known in Catamarca.

This group is not fossiliferous, but in its lithological characters
recalls the divisions of the Iraty and Estrada Nova (Passa Dois)
series of Brazil and Uruguay, more particularly as developed in the
latter country. Its age is probably lower Permian.

Stage III — Transitional from the foregoing and from 300 to 500
meters in thickness, come quartzitic sandstones, dark arkoses, and
conglomerates (particularly towards the top), while the softer beds
are darker and there is less calcareous matter present, but lime¬
stone — occasionally silicified — still occurs and gypsum is sometimes
found, as in the Puna de Atacama. On several horizons, both in this
and in Stage II, have been recorded contemporaneous basaltic flows,
also augite-porphyrite and occasionally tuff, for example, in the
Troya Valley (Puna de Atacama), Cerro Villa Union, Cerro Bola,
and at and to the north of Paganzo— forerunners obviously of the
marked volcanicity of the late Triassic.

Unusual interest attaches to its development in the Puna de
Atacama, where, according to Penck,71 a thickness of over 900 meters
is represented with some melaphyres at the top, the red-brown sand¬
stones being fine-grained and diagonally-bedded to platy, while the
calcareous thin-bedded, fine-grained beds carry siliceous layers and
concretions and gray, red, and violet “marls,” observations which
suggest that this succession actually includes part of the Trias-
Rhaetic Stage IV, and may even be in part equivalent to the Estrada
Nova and Rio do Rasto of Brazil. In a remarkable facies arising
through alteration by granite, these reddish beds have been con¬
verted into gray, yellow, red, and violet quartzites containing a fos¬
siliferous zone of white porcellanous shales in the lofty Tolarcito
Pass (lat. 2 70 15'), which has yielded a scanty marine fauna (Ana-
plophora , Avicula, etc.), indicating a Triassic age.72 These are the
only fossils known from this stage, and should be compared with
those from the Estrada Nova (see page 150).

Stage IV, the Trias-Rhxtic — The so-called “Rhaetic beds” — as
usually indicated by the presence of the ‘ ‘ Thinnfeldia flora ’ ’ — out¬
crop in quite a number of places between Mendoza in the south and
Famatina in the north and between the Andes in the west and perhaps
Cordoba in the east, though occupying a more restricted area than
the older stages. In the northern half of Patagonia, however, their
equivalents have been found to make a wide distribution.

71 Penck (1920), pp. 132-133. 72 Penck (1920), p. 151.

46 GEOLOGICAL COMPARISON OF SOUTH AMERICA WITH SOUTH AFRICA

As mentioned already, the late Permian or early Triassic earth
movements (Gondwanides) led to the folding and to the subsequent
erosion of the lower stages of the Paganzo, and so enabled the suc¬
ceeding Mesozoic formations to transgress across the edges of the
latter. At quite a number of places the unconformable relationship of
the younger beds can be studied, but in the northwest, in the but
little disturbed tract between the Sierra de Paganzo and the Cerro
Villa Union, there is reported to be an apparently unbroken succes¬
sion from Stage III into Stage IV, and from the latter in turn into
beds that may just possibly be Jurassic,73 tentatively referred to as
Stage V.

This region embraces by far the largest continuous area in the
pre-Cordillera, the other widely scattered localities being those at
Barreal and Jarillal in the valley of the Rio de los Patos west of San
Juan; the important elevated mass of the Paramillo overlooking the
Uspallata Valley; Salagasta, San Isidro, Challao, Potrerillos, and
Cacheuta among the foot-hills of the Mendoza district ; and Marayes
on the southwest side of the Sierra de la Huerta ; but not in the Sierra
de los Llanos or Sierra de San Luis. This stage is only doubtfully
present in the Sierra de Umango and is not known in the Nevado de
Famatina, though it has its equivalent farther to the northeast and
north in the districts of Tucuman, Jujuy, and onward into Bolivia,
to which reference will be made below. In the east, beds regarded as
Triassic are known in various parts of the Sierra de Cordoba, while
the deep bore-hole at Alhuampa on the Central Norte Railway in
Santiago del Estero proved nearly flat-lying Trias-Rhaetic ( ?) beds
from the depth of about 1,340 meters downward, having Permian
most probably (with Schizoneura and Phyllotheca ) below 1,700 meters
down to 2,111 meters — a link with the strata forming the vast
Triassic plateau of Uruguay and Paraguay.

In the main region between Cerro Villa Union and the Sierra de
Paganzo, Bodenbender has recorded this stage as extending along
the eastern side of the Cerro Bola, dipping eastward and covering
the wide stretch made by the Cerro Totorilillo, wrapping around
the northern end of Sierra del Valle Fertil, reaching almost to the
Sierra del Cerro Blanco, and occurring again on the eastern side of that
range of crystallines, where, at El Molle, it reposes upon conglomer¬
ates taken, though not without some doubt, as the top of Stage III ;
the same relationship is seen in the Cerro Morado a little to the west
and again on the eastern side of the Cerro Bola. A thickness of
between 400 and 500 meters is represented, consisting of gray arkoses
and yellow sandstones, from coarse to fine, with intercalations of
carbonaceous shales, carrying plant remains, chiefly Thinnfeldia,
and a seam of coal about 1 meter thick on the western side of the

73 Bodenbender (1911), p. 124.

ARGENTINA AND BOLIVIA

Cerro Morado and impure seams at Marayes farther to the south.
In addition, intercalated flows of olivine-basalt are known on at
least two horizons, such volcanic rocks crowning some of the ridges,
such as the Cerro Morado. These beds are most probably of Upper
Triassic age.

The group is followed with complete conformity by Stage V, some
400 to 500 meters of strata, including marls with many calcareous
nodules and sometimes of concretions of barite, by sandstones, and
by whitish-yellow or grayish, white, red, and green clays, passing up
into light sandstone, and by brilliant red sandstones and clays with
gypsum. Trunks of Araucarian type have been recorded from a
point east of the Sierra de Cerro Blanco. Bodenbender has proposed a
Jurassic age for the lower part of this division and a Cretaceous one
for the upper part, but there seem to be no valid reasons why these
strata should not be Rhaeto-Lias, as is suggested by the sections
near Barreal.

At Hilario, a little to the north of that village, I found Stage IV
resting unconformably on tilted lower Palaeozoics, its base being
crowded with chips of green slates and greywackes derived there¬
from, followed by sandstones with cherty layers and dark fissile
cherts, white shales, thin layers of volcanic ash, grits, and some con¬
glomerates. In the Quebrada del Jarillal, a few kilometers to the
south, higher beds are finely exposed (Plate IX, A), with soft vari¬
egated shales and dark shales carrying numerous well-preserved
plants ( Thinnfeldia , Txniopteris, Baiera , Cladophlebis, Phcenicopsis ,
etc., and silicified wood, probably Dadoxylon ) and some torbanite-
like bands. Similar soft gray beds appear in the Quebrada del Salto
due east of Barreal, wherein, below a band of gray clays with Thinn¬
feldia , were found some lenses of a green rock with what seemed to be
traces of marine fossils, though not identifiable. Both here and at the
Quebrada del Jarillal these plant-bearing beds are followed by vivid
red conglomerates and sandstones (Stage V, Plate IX, B), which,
though regarded by Stappenbeck 74 as Cretaceous, appear to be quite
conformable, there being an actual interlamination of pink and gray
clays with small-pebble conglomerate about the junction, a character
to be found duplicated in the Mendoza district.

Time only permitted of a single rapid traverse across the high-
lying Paramillo region, described originally by Stelzner 75 and Ave-
Lallemant 76 and briefly by Stappenbeck.77 On the east, resting upon
tilted Devonian (?) slates, one finds gently inclined hard sandstones,
arkoses, and greenish shales in which Keidel 78 has discovered Cyzicus
(. Estheria ), like the beds characterizing the middle of the group at

74 Stappenbeck (1910), pp. 56, 66. 77 Stappenbeck (1910), pp. 60-61.

75 Stelzner (1878). 78 Verbal communication.

76 Av6-Lallemant (1890).

48 GEOLOGICAL COMPARISON OF SOUTH AMERICA WITH SOUTH AFRICA

Challao, overlain by andesitic lavas, and followed by similar sedi¬
ments to a total thickness of several hundred meters. Conspicuous
is a splendid section along the main road, displaying a large number
of coniferous tree-trunks (probably Dadoxylon) , standing upright
(Plate X, A), rooted in a sandstone bed and surrounded by drab-
colored tuff, above which comes a sandstone which the stems do not
penetrate. This horizon was noticed by Ave-Lallamant and termed
by him “the sandstone with Araucarias. ” On the water-shed these
beds give place to a group of thin sandstones, dark shales, and
bituminous shales with tuffs and basaltic intercalations to a thickness
of perhaps 120 or 150 meters. The bituminous shales occur as thin
bands, weathering with a bluish-gray or white exterior and brownish
to blackish interior, giving out a wooden sound when struck with the
hammer; they are clearly allied to the torbanites, and are crowded
with the carapaces of Estheria and contain occasional scales of
Semionotus. Some thin limestones and cherts have been recorded
from these beds by Stappenbeck, while plants have been obtained at
a number of points, including Thinnfeldia, Tasniopteris, Baiera , etc.

That the basaltic layers are extrusive, though generally quite
compact, is shown by the presence of small vesicles either at top or
base, or in some instances by a zone of “pipe-amygdaloid” at the
bottom, and by the fact that the shales may rest in the unaltered
state on a slightly uneven surface of the igneous rock. In addition
to these lavas, intrusive sills of andesite cut these beds.

In the Cerro Colorado, lying to the west, the plant-bearing shales
and white and gray tufaceous sandstones pass up into red and green
clays and false-bedded red sandstones with clays, pierced and over-
lain by intrusive andesite, these strata being viewed by Stappen¬
beck as Cretaceous, but being more probably of Rhsetic or Liassic
age. The total thickness of the sediments involved in the Para-
millo ascribable to Stages IV and V may perhaps possess a value of
1,000 meters.

At Challao, 7 km. to the northwest of Mendoza, the succession,
which I estimate to be not less than 450 meters in thickness, begins
with a massive basal conglomerate, deep red in color, resting on
tilted Palaeozoics, passing up through red sandstone and pale sand¬
stone and greenish shales, arkoses, etc., into a group of well laminated
shales, banded cherty shales, dark “papery shales,” and torbanite-
like layers standing almost vertically, of which latter thin-bedded
strata some details are given by Stappenbeck, and ending in a thick
mass of sandstones of red or gray- violet tint, so-called “Cretaceous. ”
Noteworthy is the abundance of Estheria ( E . draperi and not E.
mangliensis) , not only in the shales and gray cherty layers, but in
the associated sandstone beds and carbonaceous bands. The latter
are much weathered and plant remains are hence difficult to obtain

ARGENTINA AND BOLIVIA

> *

vsv:-;

now; Cladophlebis mesozoica Kurtz has been recorded here, while
Keidel has discovered remains of Gyporella in a gray dolomite.79 In

a block of yellowish sandstone from a horizon
about midway in the group and at least 200
meters below the Estheria beds — unfortunately
too large to be removed — I obtained on develop¬
ment an impression of Glossopteris, probably G.
angustifolia, a long pinna of Marattiopsis , prob¬
ably allied to M. muensteri, and a large equiseta-
ceous stem, which would indicate a Triassic age
for this part of the formation.

At Potrerillos, on the Transandine Railway
o kv "K * • between Mendoza and Uspallata, is to be found

a very similar and complete section in the Cerro
de las Cabras displaying fully 700 meters of beds
dipping southward at moderately high angles
(Fig. 5), wdiich, in the light of the foregoing de¬
scriptions, I am inclined to interpret differently
to Stappenbeck.80 The formation is underlain by
porphyritic and other volcanics (a) and com¬
mences with deep-red conglomerates and small
pebble breccias some 150 meters thick ( b ), fol¬
lowed by transitional beds of pink clays and
grits (c) into yellow sandstones, grits, gray shales
and mudstones (d), from the midst of which
Estheria and Thinnfeldia were collected at (e).
Conspicuous is next a red small-pebble conglom¬
erate (/) and some distance above that a body
of 15 meters of black and gray shales with car¬
bonaceous mudstones (g) yielding scales of
Semionotus , passing up without a break into
dark-maroon shales (h) with yellow sandstones
*'oo ^ (i), after which appear vermilion grits and small-

pebble conglomerates (j), seemingly the beds
regarded by Stappenbeck as Cretaceous.

There is, however, no break discernible in
the entire succession and the alternation of deep
red with the normal and often black strata, ex¬
ceptionally well seen in the Cerro Bayo, would
show that this upper and predominantly red for¬
mation must be perfectly conformable with the
beds below and consequently ought to be grouped
with the Paganzo, though it could very con-

79 Stappenbeck (1910), p. 62.

80 Stappenbeck (1917), p. 21.

"T3

• rH

ctf

Q
cJ
>■ ■<

y 1 ■<

l-H

50 GEOLOGICAL COMPARISON OF SOUTH AMERICA WITH SOUTH AFRICA

veniently be considered as forming * ‘ Stage V. ” At Potrerillos it is
overlain with a break by the tilted Pliocene “ Calchaquenos. ”

At the southern end of the Cerro de Cacheuta, 20 km. to the
southeast, is the classic section at the back of the Mina de Petroleo.81
Here the beds dip at 20° to the south, displaying at their base
porphyritic lavas and keratophyres, then 35 meters of tufaceous
sandstones, 15 meters of bituminous shales (lower), 20 meters of
sandstones, and 8 meters of thin-bedded gray shales with plants, 73
meters of coarse sandstones, gray conglomeratic sandstones, etc.,
70 meters of bituminous shales (upper), while quite conformably
above come 130 meters of red, gray, and violet and gray sandstones
and shales with some gypsiferous bands (Stage V), overlain by a great
mass of Tertiaries.82 Plants are best preserved in the gray shales and
scarcely in the highly carbonaceous bands — most abundantly
Thinnfeldia , Baiera , Cladophlebis, Stenopteris, etc.83 Striking is the
abundance of Cyzicus (. Estheria ) draperi Jones, with which the bitum¬
inous shales are crowded, and which organism has not improbably
been responsible for the petroleum seeping out from the outcrop of
the lower shales, also struck in bore-holes to the south beneath the
Tertiary covering, in the sandstones overlying those shales, where
the formation has been bent into a dome. The petroleum is un¬
usually high in its content of paraffin wax.

Occurrences Outside the Pre-Cordillera — Most illuminating are
certain localities where the Trias-Rhaetic is present in the Cordillera
of Chile and Argentina and also in Patagonia.

Of particular interest is the isolated patch at La Ternera,84
northeast of Copiapo (lat. 270 12', long. 69° 50'), where, in perfect
conformity beneath nearly vertical tuffs including a limestone bed
carrying a decidedly lower Liassic marine fauna, comes a 50-meter-
thick group containing conglomerates with porphyry pebbles, sand¬
stones, shales with cherty bands, clay ironstone, and impure coals
in layers and streaks, the bottom in contact with a mass of porphy-
rite, apparently intrusive. From this group, which lithologically
shows close resemblances with the occurrences in the San Juan and
Mendoza districts, Solms-Laubach has described a flora with
Thinnfeldia , Txniopteris, etc., while Estheria also occurs, and fossil
wood. The horizon represented here must undoubtedly be the
Rhaetic, and, significantly, includes certain genera not known in
Argentina, such as Dictyophyllum, Lesley a } Clathropteris, Copiapxa , etc.

The presence of the upper Triassic ocean is proved to the south¬
west by the finding on the Rio de Huasco of beds resting directly on
granite and crystalline schists (of which they carry pebbles) con-

81 Stappenbeck (1910), p. 65; (1917), pp. 22, 45.

82 From a measured section furnished me by Mr. H. J. Hawley.

83 Szajnocha (1888).

84Steinmann and Solms-Laubach (1899).

ARGENTINA AND BOLIVIA

taining Halobia , while farther down the coast, near the Rio Choapa,
Groeber 85 has discovered strata containing that genus and also Pseu-
domonotis , as well as older beds of Permian or more probably Car¬
boniferous age carrying Productus.

Groeber 86 has summarized information on the supra-Triassic and
pointed out that at Puente del Inca, Rio de las Vacas, and the region
of Espinacito to the west of Uspallata the Callovian, Dogger, or Lias
overlap quartz-porphyries, porphyrites, and melaphyres belonging to
Stage IV (or V) which rest discordantly on possibly Devonian rocks,
while, as remarked earlier, they appear again in the Sierra Pintada
to the south and are of importance in the area between the Rio Atuel
and the Rio Neuquen, where they are covered by Liassic or Jurassic
marine beds, the “Paganzo” (with its original significance) being
absent ; quartz-porphyries and tuffs here play a very important role.
Groeber regards this mainly volcanic assemblage of the Cordillera,
extending roughly north and south and having a thickness of up to
i,ooo meters, as wholly of upper Triassic age, but points out that
there are actually similar volcanics in the overlying Liassic as well.
Of immense importance is his discovery that near Las Lajas (lat.
39°, long. 710) on the Chilean border the first-mentioned group of
volcanics succeed marine middle or upper Triassic beds, which are
resting unconformably on the ancient platform, and that the Dogger
overlies these volcanics and has a basal conglomerate with pebbles
derived from the latter.87

From the sub-Andine zone in Chubut (Patagonia) to the south¬
east, Keidel 88 has described crystal tuffs, brilliantly colored tuffs,
calcareous shales, etc., crowded with Estheria draperi. Porphyrites,
agglomerates, and tuffs are mentioned by Rassmuss 89 at the head of
the Rfo Chubut, while similar beds are recorded by Windhausen 90
from the Rfo Chubut, the neighborhood of Sarmiento, and from the
Rfo Deseado, San Julian, and other places farther south in Santa
Cruz. Quartz-porphyries, rhyolitic rocks, and keratophyres are
known in various places, but it is somewhat difficult from a study of
the literature alone to obtain a clear idea as to the precise relation of
these effusions to the pyroclastic rocks, more especially as Rassmuss
remarks that bodies of intrusive granite and grano-diorite, probably
of Jurassic age, occur in the upper part of the Rfo Chubut. It is
certain, however, that this assemblage, with a maximum recorded
thickness on the coast of over 900 meters, rests upon the crystalline
basement and has been bent into moderate folds along arcs trending
roughly south-southeast to southeast as the result of movements
during the mid-Cretaceous, and are overlain unconformably by

“Groeber (1922). “Keidel (1917-18).

“Groeber (1918), pp. 49-59. 89 Rassmuss (1922).

87 Verbal communication. 90 Windhausen (1921, 1924).

52 GEOLOGICAL COMPARISON OP SOUTH AMERICA WITH SOUTH AFRICA

almost undisturbed upper Cretaceous, Tertiary, or Quaternary;
they moreover show out at intervals over a great area stretching
southward into Terra del Fuego.

The presence of Cyzicus (. Estheria ) draperi and of silicified wrood
enables comparison to be made with the so-called “Rhaetic” of the
Mendoza district. In the latter are to be found the beginnings of the
acid effusions and fragmental rocks that have such a development to
the south and southeast, though not represented in other parts of
South America. In South Africa, however, are the comparable and
immense acid outpourings of the Lebombo on the southeastern side
of that continent, with certain intrusive granophyric, felsitic, and
dioritic masses, all of Stormberg age (Rhaeto-Lias) , while at Brisbane
in Queensland the base of the Triassic Ipswich series is made by a
bed of quartz-porphyry tuff resting on the vertical edges of schists,
while rhyolites, dacites and andesites are also known from this
neighborhood.

A matter to which attention should be drawn is the presence in
the southwestern corner of the Neuquen district of Neocomian beds
carrying molluscan fossils typical of the Uitenhage series of the
Cape, such as Holcostephanus atherstonei, H. rogersi, H. uitenhagensis ,
Trigonia ventricosa, T. aff. rogersi , T. transitoria allied to T. hertzogi ,
T. eximia allied to T. conocar diiformis, T. pusilla and other forms
related to T. van, Grammatodon jonesi, Exogyra imbricata , etc.91

This locality, situated to the southwest of the arc of the
“ Gondwanides, ” shows therefore a very close analogy with the geol¬
ogy of the Uitenhage district of the Cape, as will be discussed at
a later place.

The Occurrences in the Pampean Ranges — Constituting a link
between the west and the center are the exposures at Marayes along
the southern base of the Sierra de la Huerta, where, sandwiched
between two groups of chocolate- and maroon-colored conglomeratic
strata, come some 150 meters of greenish and buff sandstones with
thin shales and coals (the so-called “Rhaetic,” Plate X, B)\ the
basal group rests upon an uneven surface of the crystallines. In the
sections exposed at the Rickard Mine and at Carrizal there seemed
to me to be a conformable succession, but according to Rassmuss
what would appear to be an intraformational unconformity is present,
the ‘ ‘ Rhaetic ’ ’ transgressing across the lower group of the ‘ ‘ Paganzo ’ ’
and coming to rest directly upon the crystallines when followed
toward the north.92 The upper group of deeply colored rocks, fully
400 meters thick, is referred to by him as of Cretaceous age, but since
it recalls the succession already described in the region to the west,
and appears to follow conformably upon the Rhaetic within this

9X Letter written me by Dr. Pablo Groeber dated June 7, 1926.

92 Rassmuss (1922a).

ARGENTINA AND BOLIVIA

trough, it can provisionally be considered as forming the uppermost
portion of the Paganzo system, Stage V. The assemblages can hence
be placed in the Trias-Lias succession. The coals at the Rickard
Mine and at Carrizal are very thin, high in ash, and extremely pyritic.
In addition to calcified coniferous stems, the middle group has
yielded the Thinnfeldia flora, this being the most southeasterly point
where such has been recorded in Argentina,93 with the probable
exception of the strata with Cladophlebis mesozoica resting on the
granite in the Sierra de los Llanos.94

Turning attention to the Central Pampean ranges, the eastern¬
most outcrop of beds, that on lithological grounds have been ascribed
to the Triassic, are to be found in the Sierra de Cordoba,95 forming
a series of patches resting upon an uneven surface of gneiss, Palaeo¬
zoic (?) limestones, etc., in some places horizontally, in others tilted
and faulted. At Saldan, just north of Cordoba, the series consists of
ioo meters of red conglomerates, passing up into deep-red sandstones
with some red shaly layers (Plate XI, A). Ripple-marked and sun-
cracked surfaces are present and the sandstones are markedly cross-
bedded, recalling the upper Triassic seen elsewhere. In Los Terrones,
northeast of Capilla del Monte, are splendid sections through at least
200 meters of red conglomeratic beds, weathered out into striking
erosional forms (Plate XI, B). The gneiss surface beneath is highly
uneven and the junction here is not a faulted one, as maintained by
Rimann.96 Some volcanic rocks overlie the strata at La Cumbre, but
the circumstances rather suggest an unconformable relationship and
a much younger age.

Provisionally these sediments can be allotted to the top of the
Paganzo, but, inasmuch as coals are reported to occur to the south
of Cordoba along the line of strike of the Saldan conglomerates,
plants should shortly be forthcoming to decide this question, which
is an important one, since these are the easternmost outcrops of
such beds in the republic.

The Thinnfeldia Flora — Some remarks might be made on the
composition of this flora and its bearing on the age of the inclosing
strata.

The several florules in western Argentina, occurring as they do
each in a group of gray or carbonaceous shales, sometimes accom¬
panied by impure coals, sandwiched between groups of coarser vari¬
egated sediments, represent with but little doubt practically one and
the same horizon situated not very far from the middle of Stage IV,
being followed by the red strata placed by me in Stage V, correlated
provisionally with the Botucatu of Brazil.

From those sections of Gondwanaland, that possess beds carry-

93Geinitz (1876); Gothan (1925).

84 Vide Keidel (1922), pp. 288-290.

95 Bodenbender (1905).

96 Rimann (1918).

54 GEOLOGICAL COMPARISON OF SOUTH AMERICA WITH SOUTH AFRICA

ing the Thinnjeldia flora, the formation that is most suitable for age
determination is undoubtedly the Molteno beds of the Stormberg
series of the Cape, because this group fortunately happens to be
succeeded by strata containing vertebrate remains (saurischian and
pseudosuehian) of typical European Keuper and Rhaetic genera, and
its flora can consequently be regarded as not younger than upper¬
most Keuper.

Comparisons of the South African and East Australian (especially
the Ipswich) assemblages with that of Argentina reveal marked
resemblances, which the few published descriptions of the latter fail
to do justice to, since many of those determinations were based on
mere fragments. We find as common species Thinnfeldia odontopter-
oides (Morr), T. lancifolia (Morr), and T. feistmanteli John. ( Cardi -
opteris zuberi Szaj.), while certain large fronds from Cacheuta placed
by Kurtz97 under T. lancifolia are not far removed from T. narra-
beenensis Walkom from the Triassic Hawkesbury series of New South
Wales, and are also very similar to Danxopsis hughesi Feist, a form
known from the Stormberg, Australia, and perhaps Argentina
(Potrerillos) . Txniopteris mareyesiaca Gein. is indistinguishable from
T. dunstani Walk, from Queensland; T. brackebushiana Kurtz from
Cacheuta has lately been identified in the Cape, while T. carruthersi
and T. m'clellandi (Old. and Morr), known from Queensland and
Southern Rhodesia, have been discovered at Barreal. Another recent
identification is Cladophlebis goppertiana (Schen.) both at Barreal
and in Natal (South Africa) the forms referred to Sphenopteris
elongata, and under Phcenicopsis elongata (Morr) the leaves described
as Podozamites elongatus , the last two being known from South Africa
and Australia. The form Chiropteris copiapensis Stein, et Solms, from
La Ternera in Chile and from Cacheuta, is also known from the
Molteno beds.

In addition, the widely distributed crustacean Cyzicus (. Estheria )
is the same species as originally described from the Cave sandstone of
South Africa, E. draperi Jones, the associated smaller individuals then
called E. stowiana being now regarded as representing the youthful
stage. The fish-scales referred to Semionotus mendozaensis Gein. are,
moreover, comparable with those of S. capensis S.-Woodw., from the
Cave sandstone.

The above comparisons bring out the great similarities in the
floras of western Argentina, the Cape, eastern Australia, and Tas¬
mania, apart from strong lithological resemblances in these beds,
and stage IV can accordingly be regarded as belonging with more
probability to the upper Triassic (Keuper) than to the Rhastic, in
which these beds have hitherto universally been placed. The flora of
the Upper Paganzo is quite different in its composition from that of

97 Kurtz (1921-22), PI. XIX.

ARGENTINA AND BOLIVIA

the undoubtedly Liassic flora with Otozamites and Dictyophyllum
known close at hand in the upper part of the Rio Atuel, and differs
in several essentials from that at La Ternera, which, as shown by the
marine fossils above, is almost certainly not earlier than Rhaetic. The
small assemblage described by Berry98 from far to the south in
Patagonia, in the Gran Bajo de San Julian associated with Estheria
draperi in the upper part of a thick mass of quartz-porphyry tuffs
containing a few coaly bands,99 displays, on the other hand, Liassic
affinities. Gothan 1 has also expressed doubt as to whether the beds
at the Cerro Alto in Santa Cruz that have yielded the interesting
cone of Araucaria windhauseni are as low as the Triassic, as supposed
by Windhausen.

SECTION G. THE PRE-ANDINE BELT OF NORTHERN ARGENTINA

AND OF BOLIVIA

Of high importance are the recent discoveries pointing to a wide
distribution of the Permo-Triassic continental beds in Tucuman,
Salta, and Jujuy, stretching into Bolivia as far to the north as Santa
Cruz at least in the pre-Andine chains bordering the plain of the
Gran Chaco. The strata are exposed, for example, in the various
ranges, proceeding from south to north, of the Sierra de Lumbrera,
Sierra de Santa Barbara, Sierra del Alto, Sierra de Aguaragwe, Sierra
de Mandiyuti, Sierra de Charagua, and Sierra de Santa Cruz.

The southernmost outcrops, seen a little to the northeast of
Tucuman, are separated by quite a considerable stretch of more
ancient rocks from the patches of the equivalent Paganzo to the
northwest of Tinogasta in the Puna de Atacama or those of La Rioja
and Cordoba, and there is no actual connection between the latter
and the “Bermejo series, ” as this northern facies has been named by
Heald and Mather.2 Nevertheless, a few representatives of the
Gondwana flora have been found, while the generally marked litho¬
logical resemblance points to such a correlation. Further importance
attaches in that there may be an unbroken succession right through
into the Jurassic, whereas in the rest of South America almost
everywhere either a definite unconformity or else a pseudo-con¬
formity is present at about the top of the Permian or near the base
of the Triassic.

The beds make their appearance in a series of narrow and often
faulted anticlines from beneath tilted Cretaceous and Tertiary, but
without the intense crumpling and the igneous injection that charac¬
terizes the equivalent formations to the south and southwest, in which
structures at a number of points from Salta northward fossiliferous

98 Berry (1924).
"Wichmann (1922).

1 Gothan (1925).

2 Heald and Mather (1922); Mather (1922).

56 GEOLOGICAL COMPARISON OF SOUTH AMERICA WITH SOUTH AFRICA

shaly beds, of Devonian age with a typical austral marine fauna,
form the cores. These ranges constitute the eastern Cordillera.

The upper limit of the Bermejo series, through a distance of many
degrees, right up to the northwest and west of Potosi in fact, is
formed by the relatively thin calcareous member with marine
fossils — the “Limestones and dolomites with Melania ” of D’Orbigny3
or the “Horizonte Calcareo-Dolomitico” of Bonarelli,4 also called by
Heald and Mather the “Viticua limestone” from the range of that
name (lat. 20°. 15' S.) and the “Cajones limestone” in the Santa
Cruz area.

This valuable datum, from 5 to 40 meters thick, consists of white,
pink, gray, or bluish hard limestones and dolomites in very regular
thin layers, together with chert in layers or lenses — sometimes
oolitic — the rocks being much silicified in places. They pass upward
into a group of variegated Keuper-like marls with thin calcareous
intercalations, also fossiliferous, up to 150 meters in thickness in the
south. These various limestones are characterized by the presence
of Chemnitzia {Melania) potosiensis (D’Orb.), and have yielded a con¬
siderable fauna, mainly gasteropods, which Bonarelli has shown to
point to an uppermost Triassic or Liassic age.5 The sandstones over-
lying the marls are apparently unconformable and most probably of
Cretaceous age.

Perfectly conformable beneath the limestone come the uppermost
sandstones of the Bermejo series — the “lower sandstones” (arenis-
cas inferiores) of Bonarelli — but in the Puna de Jujuy the latter thin
out and the limestone, according to Bonarelli, come to rest either
directly or with a thin basal conglomerate on the Ordovician, the
Devonian being absent.6 In the Sierra de Zapla, close to Jujuy, the
Bermejo is only some 400 to 500 meters thick, but more to the north
it ranges generally from 1,300 to 1,500 meters, attaining its maximum
of 2,500 meters in the Sierra del Alto (about lat. 22 0 S.). While the
series usually rests with unconformity upon the Devonian, in certain
places no marked discordance has been detected between it and that
formation below.7

Long ago D’Orbigny had observed that over a wide tract to the
northeast of the area under consideration, in the neighborhood of
Lake Titicaca, the Devonian was followed by marine Carboniferous,
which has since been proved over an extensive region around Cocha¬
bamba and also to the southwest of Santa Cruz on the “alt a planicie ”
or high plateau of Bolivia. The fauna, including Productus cora
D’Orb., P. nebraskensis Owen, P. clarkianus Derby, Spirifer condor
D’Orb., Spiriferina cristata Schloth, Fenestella retiformis Schloth, is
that of the Uralian of the Urals, Salt Range of India, and Guada-

3 D’Orbigny (1842). 6 Bonarelli (1921), p. 74; Jaworski (1923). 7 Meyer (1914).

4 Bonarelli (1921). *Ibid., p. 21.

ARGENTINA AND BOLIVIA

lupian of New Mexico, and has species in common with the Carboni¬
ferous of the Amazon Valley and to a less degree with that of
the Sahara.

On the shores of Lake Titicaca, Douglas 8 observed red and choco¬
late colored sandstones and breccias following the Carboniferous
limestones and shales conformably, but 50 km. to the southeast, at
Coniri, the highest beds of the former consist of coarse reddish con¬
glomerates with pebbles, some of which are of fossiliferous Carboni¬
ferous limestone. These deeply colored rocks possibly represent the
Bermejo series. A long distance to the southeast, not far to the south¬
west of Santa Cruz, the undoubted Bermejo rests discordantly on the
arenaceous “Materal formation,” which is believed by Heald and
Mather9 to be itself unconformable to the Devonian slates, and which
may perhaps be the continental facies of the Titicaca Carboniferous.

Thus delimited above and below, the Bermejo is considered to
range from the Permian to the base of the Jurassic, though, except
for the mollusca at the top of the series, the only fossils yet recorded
consist of Equisetites and Phyllotheca from Lipeon, northwest of
Oran in Argentina, and some Lingulas from above the glacials in
the Sierra de Santa Cruz.

Its lowest division — the Oquita formation10 — is dominantly a gray
sandstone followed by sandy shales and these by cream or red sand¬
stones, or in the Sierra de Aguaragwe by massive white sandstones,
wThile the uppermost part is composed of persistent sandy shales of
various colors and thin-bedded sandstones. Certain shaly bands may
possibly be of glacio-lacustrine origin, seen, for example, in the
Parapiti Gorge (lat. 20° S.). The middle division is the striking
Mandiyuti conglomerate, which builds many of the rugged cliffs and
gives rise to picturesque scenery. It consists of massively bedded
conglomerate and grit, together with sandstones, and varies from
500 meters in the northern part of the Sierra de Aguaragwe on the
border of Argentina to 1,000 meters in the type locality in the
Sierra de Mandiyuti farther to the north (lat. 20° 30' S.) ; individual
beds as much as 80 meters in thickness occur in the midst of the
formation at several localities. The majority of the beds display
brilliant shades of red and purple.

The pebbles in the conglomerates and grits are of all sizes and
shapes and up to nearly a meter in length, mainly of hard rocks and
mostly well rounded and polished by stream or current action, but in
every locality are to be found many angular pebbles with faceted
faces, and the deposit is therefore regarded by Heald and Mather as
a fluvio- glacial accumulation. In the presumably equivalent beds in
the Sierra de Santa Cruz tough clays were found carrying beautifully

8 Douglas (1914), p. 30. 10 Mather (1922), p. 739.

9 Heald and Mather (1922), p. 560.

58 GEOLOGICAL COMPARISON OF SOUTH AMERICA WITH SOUTH AFRICA

faceted grains and pebbles, while true tillite was also observed by
them. These faceted inclusions scattered through both the sand¬
stones and shales clearly indicate the presence of streams issuing
from a glacier-front or from glacier-capped highlands.

Though paralleled by Heald and Mather with the (Carboniferous)
glacials of the San Juan-Jachal area, it must not be overlooked that
they may not improbably be much higher in the succession, possibly
well up in the Permian, and that they might even be comparable with
the glacials of the upper Marine series of the Hunter River area in
New South Wales or perhaps those of the Congo, ascribable to a
Triassic (or probably late Permian) age according to Ball and Shaler.

The uppermost division of the Bermejo series ranges from 250
to 500 meters in thickness, mainly massive soft green to maroon
sandstones, with non-fissile shales and clays of red color, overlain
conformably by the “ calcareo-dolomitic horizon.” Madgwick has
remarked on the highly false-bedded nature of these sandstones,
wherefore comparison can be instituted with the Rio do Rasto series
of the Santa Catherina system of Brazil, the nearest occurrences of
which lie less than 800 km. due east on the railway from Porto
Esperanga to Sao Paulo.

This upper Bermejo (areniscas inferiores) appears in the Cerro
Colorado, west of Rosario de la Frontera in Salta, beneath the lime¬
stones to a thickness of 600 meters at least without the base being
seen, yet in the Alto de Munoz and to the south in the Cerro de
Campo this group rests directly on the pre-Cambrian; clearly the
lower Bermejo does not reach Salta.11 The upper Bermejo, the lime¬
stones, and the marls above together make up the “formation
petrollfera” of Bonarelli, in which much boring has been done at the
base of the various chains.

That the Permo-Triassic extends far to the east beneath the
covering of Cretaceo-Tertiary is indicated by the deep boring at
Alhuampa previously mentioned, in which at a depth of some 1,340
meters there was cut a group of dark-reddish micaceous sandstones
and clays with occasional conglomerates, down to about 1,700 meters
possibly Triassic, and below that down to 2,111 meters light feld-
spathic and micaceous sandstones and grits with dark micaceous
shales, which at 1,860 meters yielded impressions of Schizoneura and
Phyllo theca, indicating some stage of the Paganzo. It should be
noticed that the volcanic rocks, so well represented in the Parana
Basin and found in borings just east of the Parana River, and also the
flows associated with Stage IV in La Rioja, are absent from the
northern belt just described.

11 Stappenbeck (1921).

CHAPTER IV

PRE-GONDWANA BASEMENT OF EASTERN SOUTH AMERICA

SECTION H. THE DEVONIAN SYSTEM

In all Brazil perhaps the most striking parallel with the Cape is
afforded by the central portion of the State of Parana with its
Devono-Gondwana succession.12 Conspicuous here is the nearly
horizontal Furnas sandstone, making a belt curving from Faxina in
the north past Pirahy, Castro, and Ponta Grossa to Serrinha with an
outcrop of fully 300 km. in length, fading out at either end beneath
the Itarare glacial beds. The escarpment that it makes picturesque
because of its fine araucarias, is known in the north as the Serra das
Furnas and in the south as the Serra de Sant’ Anna.

The formation, which is perhaps just over 150 meters thick and
marvelously like the Table Mountain sandstone of the Cape western
Province, rests on an even surface cut equally across granite and
the tilted Assunguy series, the beds ranging from a white fine-grained
sandstone to a coarse white, false-bedded grit (Plate XII, A), con¬
taining a little kaolinized feldspar and tiny quartz pebbles, the rocks
giving rise to a coarse sandy soil and to rather treeless plains. Either
isolated in the sandstone or occurring in thin washes are pebbles
up to about 7 cm. in length, smooth and oval to irregular in outline
chiefly made of white or flesh-colored vein-quartz, together with some
of quartzites, and occasionally of cherty rocks. At Ponta Grossa I
observed none of jaspers, such as are to be found in the Clan william
district of the Cape, but Doctor Ferraz13 has ascribed to the Devonian
certain coarse sandstones with red jasper pebbles that cap the Morro
Bahu to the southeast (860 meters) not far from the coast a little to
the west of Itajahy. According to Leme,14 diamonds have been found
in the sandstones near Tibagy, a feature that has not yet been
reported from the western Cape.

The concordantly following fossiliferous Ponta Grossa shales
appear for a distance of over 200 km. between the Furnas sandstone
and the overlapping Itarare glacials ; from the descriptions available
the highest zones are represented in the central part of the great curve
in the neighborhood of Tibagy. At Ponta Grossa, where nearly 100
meters of these shales are exposed dipping gently beneath the Itarare,
the strata recall down to the minutest detail the lowermost shale
group of the Bokkeveld series of the Cape western province ranging

12Clarke (1913), pp. 36-41; Woodworth (1912), p. 42; Oliveira (1925); Branner
(1915). PP- 311-312; (1919), P- 288; Leme (1924), pp. 159-162.

13Ferraz (1921).

14 Leme (1924), p. 159.

60 GEOLOGICAL COMPARISON OF SOUTH AMERICA WITH SOUTH AFRICA

from fine carbonaceous shales with pyritic nodules through gray and
yellowish- weathering shales to soft, yellowish, sandy, and somewhat
micaceous beds; limestones are, furthermore, absent, though hard,
slightly calcareous nodules containing Lingulas are common. This
horizon has yielded abundant fossils at Ponta Grossa, Tibagy,
Jaguariahyva, etc., the palaeontological facies being closely com¬
parable with the faunal assemblages of the Bokkeveld, Falkland
Islands, Argentina, and Bolivia, as detailed by Clarke 15 and Reed 16
and summarized in Chapter VI.

Above these beds, at Tibagy, and overlain by some more shales,
is a soft, gray feldspathie sandstone — the Tibagy Sandstone — up to
20 meters thick, which is characterized by casts of large Spirifers,
and corresponding stratigraphically with the well-known soft, red-
weathering “ f ossilif erous sandstone” of the Bokkeveld with its
molds of Spirifers and other mollusca, situated about 130 meters
above the base of that series. This is all the more remarkable,
because Reed17 has just recently grouped the characteristic Tibagy
species, S. iheringi, under the name of S. ceres Reed var. iheringi
Kays, that is so abundant in the f ossilif erous sandstone of the Hex
River Valley and Warm Bokkeveld.

Except for the fact that the Table Mountain sandstone is thicker,
the lithology and succession in Parana compares almost exactly with
that of the Cape system in the northeast of Clanwilliam, where the
Dwyka tillite passes transgressively across the almost flat -lying
Bokkeveld and Table Mountain sandstone on to the folded pre-
Devonian slates and intrusive granite.

Of note is the recent discovery of such fossiliferous shales and
sandstones with Lingula , Orbiculoidea , etc., in Uruguay on the Rio
Negro at the Rincon de Alonso underlying the Itarare glacials; they
are nearly horizontal.18

In Paraguay, between 60 and 80 km. to the east-northeast of
Asuncion, at the Cerro Aparipi, and at Arroyos y Esteros, Beder and
Windhausen19 have recorded exposures of soft, medium-grained
micaceous sandstones and white, yellow, or red weathered shales
with secondary limonite ; these strata lie horizontally and must well
exceed 70 meters in thickness. To the south they must thin out
beneath the Gondwana system, for in that direction the latter come
to rest directly upon the crystallines, but the distance to which they
extend toward the northeast is as yet unknown, that region being
geologically unexplored. Windhausen has identified among forms
typical of the Ponta Grossa shales, that characteristic Hamilton
brachiopod Tropidoleptus carinatus Conrad, known from the Erere

16 Clarke (1913).

16 Reed (1925).

17 Reed (1925), p. 52.

18 Arocena (1926), p. 16.

19 Beder and Windhausen (1918).

PRE-GONDWANA BASEMENT OF EASTERN SOUTH AMERICA

sandstone of the Amazon V alley and from the Sicasica beds of Bolivia,
which accordingly suggests a mid- Devonian age and therefore a hori¬
zon somewhat higher than that present to the east in Parana.

Just as on the western so on the northwestern side of the basin
the Devonian reappears at a point 20 km. north of the town of Rio
Bonito not far from Goyaz, according to C. L. Baker,20 where shales
have yielded characteristic fossils. Better known, however, is the
plateau of the Chapada in Matto Grosso, overlooking the plain of
Cuyaba, wherein the Devonian rests unconformably upon tilted
slates and limestones of supposed Ordovician age and dips gently
northward beneath Triassic beds, the series extending in that direc¬
tion toward Diamante and eastward to Lagoinha at least, 40 km.
from Sant’ Anna de Chapada. From the remarks of Evans,21 Derby,
Leme,22 and others it would appear that the great escarpment is
made by a group of soft red sandstones with basal conglomerates
followed by shaly beds with thin sandstones. Smith puts the thick¬
ness of the first-named at 105 meters, with the fossiliferous shaly zone
in the next 50 meters, but Leme ascribes the value of 500 meters to
the series, remarking that the molluscan fauna occurs in a ferruginous
sandstone in the upper part of the group, a statement seemingly more
in accord with the observations of other visitors. The unfossiliferous
sandstones below are clearly the equivalent of the Furnas sandstone
and the fossiliferous beds above of the Pont a Grossa shales.

The fossils described by Derby and Von Ammon have been
exhaustively reviewed by Clarke,23 who points out the great simi¬
larity of the fauna to that of Parana, and to a lesser extent with that
of Bolivia, but contrast to the Maecuru fauna of Amazonas, and
remarks that the presence of the uncommon trilobite Phacops
braziliensis of boreal aspect would suggest that the Chapada Devon¬
ian, if more closely studied, would disclose additional affinities with
the fauna of the Amazon Valley, which in view of its geographically
intermediate position is only to be expected.

A point worthy of note is the statement that the diamonds of this
region have been concentrated from these Palaeozoic sandstones and
conglomerates. Scattered observations suggest that the Chapada
Devonian passes to the northeast and east beneath the Triassic sand¬
stones and basalts and the Cretaceous Bauru sandstones (‘'sand¬
stones of the Taboleiros” of Evans),24 and to the northwest of
Cuyaba beneath the Matto shales, Permian (?), while inliers to the
southwest in the Chiquitos of the Gran Chaco form links with the
Devonian of Bolivia.

An occurrence in Uruguay is worthy of mention, though ascriba-

20 Baker (1923), p. 67,

21 Evans (1894).

22 Leme (1924), p. 158.

23 Clarke (1913), pp. 41-46, p. 148.

24 Evans (1894), p. 98.

62 GEOLOGICAL COMPARISON OF SOUTH AMERICA WITH SOUTH AFRICA

ble only with doubt to the Devonian, but, if so, forming a link with
the strata in the Sierra de la Ventana. This is the limited outcrop
recorded by Walther 25 in the neighborhood of the station of Piedras
de Afilar on the Montevideo-Maldonado Railway, and quite near the
coast. Resting with presumed unconformity on the granite, though
this is not assured, and striking northwestward, the beds make a
narrow strip with a moderately high dip to the southwest, and give
rise to a sharp ridge. Though regarded by Walther as a faulted-down
outlier of the Sao Bento series, the descriptions of the rocks and the
appearance of the latter in hand specimens incline me after a dis¬
cussion with Professor Walther to suggest a greater age for the
strata, which consist mainly of a hard, fine-grained, grayish to
faintly greenish white quartzite, together with some hard reddish
sandstones. While there is the possibility that the beds may repre¬
sent a pre-Devonian formation, they resemble the quartzitic sand¬
stones of the Sierra de la Ventana. On the assumption that such is
the case, it should be noted that their strike is nearly parallel to
the course of the “ Gondwanides ’ ’ within the region to the south¬
west, and hence at right angles to the older “Brasilides” to be men¬
tioned below.

SECTION I. THE EARLY PALAEOZOIC BEDS

The several terrains of early or of pre-Palaeozoic age, though
occupying great extents of country, are surprisingly little known,
and even their relative ages are under dispute. Much discrimination
will be required in reading Branner’s26 account, for his extensive
areas classed under the Permian actually include beds ranging from
lower Palaeozoic to late Cretaceous.

Prominent are the various belts of pre-Devonian strata in the
lengthy stretch between the Rio de la Plata and Pernambuco, of
which some are probably of Ordovician age, while others may be
older. They, however, have a general lithological resemblance to the
folded Nama succession on the eastern side of the Atlantic, between
Cape Town and Luderitz, and also possess a strike that is more or
less parallel to the coast. This likeness is heightened by the fact
that in certain localities the granite by which these belts are flanked
is intrusive, just as in the Nama beds between Cape Town and
Namaqualand.

Termed many years ago the “Brazilian system” by d’Orbigny,
this tectonic structure is most probably' of Silurian age, extending
into eastern Argentina, where, by no means conspicuous, it is crossed
nearly at right angles by the Permo-Triassic “Gondwanides” (see
Fig. 7)-

In Uruguay these beds — phy llites, crystalline limestones and

25Walther (1919), p. 10, p. 77.

26Branner (1919).

PRE-GONDWANA BASEMENT OF EASTERN SOUTH AMERICA

dolomites, and quartzites — which with great probability correspond
with those of the Sierra de Tandil, occupy a well-marked belt com¬
mencing on the coast a little to the west of Maldonado and trending
between north and north-northeast through the departments of
Minas, Treinta y Tres, and Cerro Largo, in the last-named of which
they pass beneath the Gondwana beds; within the belt local devi¬
ations from the mean strike are not unusual.27 Where I saw them in
the Arroyo Fraile Muerto, to the southwest of Melo, the calcareous
rocks consisted of blue-gray, fine-grained limestones and brown and
sometimes red-weathering dolomites with subordinate dark slates,
dipping at high angles, thus resembling those of the Nama system of
Namaqualand. No fossils have yet been found in them in Uruguay.28

In southern Brazil the distribution of the limestones in the crys¬
talline complex is all but unknown in Rio Grande do Sul, though a
narrow belt possesses, so far as I can gather, an easterly strike at
Ca£apava, but in Parana the folded slates, limestones, and quartzites
of the “Assunguy series,” veined and injected by granite and quartz-
porphyry, have again a northeasterly strike, appearing from beneath
the Furnas sandstone near Curitiba, near Castro at Iporanga, and
below Xiririca and Iguape in the Ribeira Valley, and trending
through Sao Roque and Jundiahy to the northwest of Sao Paulo.
By the Brazilian Geological Survey these beds have been placed
in the Ordovician.

To the northeast of the Sao Paulo border appears the similar
and apparently equivalent “Bambuhy series” of limestones and
slates, which stretches in a wide belt down the valley of the Rio Sao
Francisco and Rio das Velhas to about the thirtieth parallel.29
Where I saw this group on the railway between Bello Horizonte and
Pirapora the thick gray and black limestones were followed by soft
micaceous shales and flagstones, the strata dipping usually at low or
moderate angles, though near Curvello they were folded along twro
axes directed northeast and northwest and the slates displayed a
cleavage and were traversed by quartz veins.

These beds were regarded by Branner as Permian, but Leme has
pointed out that they are probably continuous with the strata at Bom
Jesus de Lapa on the bank of the Rio Sao Francisco in the north, from
the limestones of which Derby described Favosites and Chastetes.
The long-reported occurrence of fossils in the limestones of the
Rio das Velhas and the recent statement of the finding of Spirifers
in limestone at Dores de Indaya, respectively north and northwest of
Bello Horizonte, and at Paracatu west of Pirapora, as cited by Leme,
all point to a Palaeozoic — probably an Ordovician or Silurian — age for

27 Walther (1919), pp. 28-38 and Plate XV.

2801iveira (1918), p. 8, (1925); Leme (1924), p. 138.

29 Leme (1924), pp. 139-143.

64 GEOLOGICAL COMPARISON OF SOUTH AMERICA WITH SOUTH AFRICA

this extensive formation with general north-northeasterly trend. It
should be noted that these foldings must be of pre-upper Carbonifer¬
ous age, since the glacial beds at Areado in the Abaete Valley rest
undisturbed on the tilted Bambuhy series.

North of Bello Horizonte the series must rest on the granite, but
between Corintho and Diamantina it is in contact with and appears
to repose unconformably upon the ancient Espina^ or Cara^a
quartzites. It is true that this relationship has been called into
question, but to my mind the section seen in the ascent of the Serra
da Toccaia at Rodeador Station clearly shows the quartzites, here
bent into an anticline, passing beneath the gently inclined limestones.

It is possible that the strata in the Serra de Caetite and those
covering so wide an area farther to the northeast in Bahia, such as
the Tombador-Caboclos-Paraguassu series described by Branner30
and Crandall,31 resting on granite or the ancient tilted Jacobina
series, are the representatives of this formation. They are bent into
open folds, with axes usually trending north-northeast and north¬
west, are overlain unconformably by the Lavras series, and this in
turn with probable disconformity by the Estancia beds and Salitre
limestones, which, as will be shown in Section M, belong to the
Permo-Carboniferous.

Immense interest attaches to the Lavras series of gray and pink
quartzites with conglomerates, inasmuch as they are most definitely
the source of the diamonds and carbonados of Bahia, with which the
similar gem-bearing quartzites of Grao Mogul in northern Minas
have been paralleled. If the stratigraphy of this region has cor¬
rectly been interpreted in the foregoing account, then there is a
strong probability that the Lavras series may be of Devonian age.
Branner has grouped it in the Carboniferous, though without palae¬
ontological evidence; Leme, on the contrary, emphasizes the sig¬
nificance of the fact that elsewhere the diamond is known to occur in
Devonian sandstones, namely, in Parana and the Chapada.

SECTION J. THE PRE-CAMBRIAN FORMATIONS

A striking feature in the geology of Minas Geraes is the long belt
of somewhat metamorphosed sediments called by Derby the ‘ ‘ Minas
series, ” deposited, it is stated, unconformably on the granite, gneiss,
and crystalline schists, but complexedly faulted and thrust by move¬
ments directed from the east and southeast.

Most fully developed between Bello Horizonte and Ouro Preto,
its basal member is the thick Cara^a or Espina^o quartzite, which
forms the “backbone” or watershed coursing northward through
Diamantina and thence northeastward toward Bahia. Above comes
the important “itabirite” or iron-ore formation, associated with

30 Branner (1910; 1919).

31 Crandall (1919).

PRE-GONDWANA BASEMENT OF EASTERN SOUTH AMERICA

dolomite, slates, etc., and followed by a group of quartzites. These
itabirites are identical with the rocks called “banded ironstones,”
so marked a type in the primitive systems of South Africa. In Bahia,
according to Crandall, the Jacobina series is probably the repre¬
sentative of these rocks of Minas.

Harder and Chamberlin32 have regarded the Minas series as
Algonkian, a view which the strong local metamorphism fully justi¬
fies; for instance, I observed kyanite in certain of the highest beds
present at the summit of the Itacolumi Peak near Ouro Preto.

Because of its alleged diamondiferous character, the Espina^o
quartzite has by certain geologists been correlated with the Lavras
quartzites of Grao Mogul and Bahia, but there are excellent reasons
for concluding that the former is a much older formation. The alle¬
gation that the gem can actually be traced up to these quartzites in
the neighborhood of Diamantina is by no means secure, several high
authorities having wholly denied this association. It is true that
diamondiferous gravels rest upon a peneplain cut across the quartz¬
ites round about Diamantina, but the gems may well have been
derived from other sources. My examination of the famous Boa
Vista Mine east of Diamantina showed most definitely that it was an
eruptive “pipe” piercing the Espina^ quartzite, the gem-bearing
but wholly “non-igneous” breccia being crowded with fragments
derived from the shattering of that formation, its somewhat schistose
character proving the antiquity of this peculiar phase of volcanicity ;
not improbably its age is pre- Devonian. Draper’s 33 researches suggest
that several of the other diamondiferous occurrences in this part of
Brazil are of a similar kind.

It is hence likely that the gems in the Lavras series were in part
derived from the waste of the Espina^o quartzites because of these
diamond-bearing pipes. Again, it is a matter of more than ordinary
interest that in South Africa the diamond should be known as a
detrital mineral in at least two formations of “pre-Kimberlite” age,
namely, in the “bankets” of the (probably) pre-Cambrian Witwaters-
rand system in the Transvaal and in the upper Triassic sandstones
of Somabula in Southern Rhodesia.

32 Harder and Chamberlin (1915).

33 Draper (1911; 1920; 1921).

CHAPTER V

GONDWANA SYSTEM IN BRAZIL, URUGUAY, AND PARAGUAY

SECTION K. THE PARANA BASIN

This covers a region of close on a million square kilometers, with¬
out taking into account certain outliers to the south and northwest,
and is therefore comparable in size with the Karroo “basin” in
South Africa, but, in contrast, the volcanic group at the top occupies
a relatively much greater area.

Within this immense territory the dips inward toward the north¬
east-southwest axis are generally extremely slight, it being rare to
find inclinations of more than about 30. Two feeble cross-ridgings
athwart the basin run northwestward through Parana and Rio
Grande do Sul respectively, while the base has been brought down
to below sea-level at Torres on the coast. In Uruguay, warping has
brought up the basement granite inside the basin in the Departments
of Riviera and Cerro Largo. On the southwest the very flat syncline
passes beneath the Neogene of the lower Parana along a line that
runs rather regularly north and south.

Stratigraphy

Termed by I. C. White34 the “Santa Catherina system,” the
subdivisions and their nomenclature have been altered from time to
time, while a different classification is employed by the Geological
Commission of Sao Paulo to that adopted by the Federal Geological
Survey of Brazil. I furthermore discovered that in Uruguay the
classification used by Professor K. Walther and by the State Boring
Department was still practically the same as that put forward by
White, but that the boundaries chosen for the several subdivisions
seemingly did not each fall at precisely the horizons adopted by the
Brazilian Survey. Such differences, however, are only to be expected
with a number of geologists laboring in an enormous territory inde¬
pendent of one another and unable to meet and discuss essentials
from time to time. Attention is drawn to this feature, since uncer¬
tainties in the way of exact correlation had arisen that I found to be
due very largely to such causes and not to errors of observation
and record.

It is regrettable that the Brazilian Coal Commission should have
labored in an area in which the highly important basal glacial divi¬
sion was so feebly developed, thus necessitating a revision in termin¬
ology for the lower part of the system at the hands of Doctor Oliveira.35

34 White (1906), p. 36. 35 Oliveira (1918), pp. 11-12.

GONDWANA SYSTEM IN BRAZIL, URUGUAY, AND PARAGUAY

I also find it impossible to subscribe to the general opinion that the
basal beds of the system are so young as Permian and am compelled
to place them in the upper part of the Carboniferous. The strati-
graphical break between the Triassic and Permian was for a long
time suspected and its recognition has come only after comparison
with other parts of Gondwanaland has indicated the presence of
such a gap in the succession. The determination by Doctor Reed
of a Triassic age for the upper part at least of the Estrada Nova
necessitates a radical alteration in the grouping of the beds and
further stratigraphical investigation is now urgently needed.

The following classification is to some extent tentative (the
wavy line indicates an unconformity or stratigraphical hiatus) :

Sao Bento series <

Serra Geral eruptives
Botucatu sandstone (where separable)
Rio do Rasto group
Estrada Nova (upper part)

Rhsetic-Liassic

► Triassic

Passa Dois series

Tuberao series

Itarare series

) Estrada Nova (lower part)
k Iraty- group
[ Palermo group
l Bonito group
(Glacial beds)

Permian

> Upper Carboniferous

(1) The Succession at Fraile Muerto in Uruguay

Before entering into a discussion upon the stratigraphy of the
basin, it will be useful to give some details concerning this small
tract of country situated 380 km. northeast of Montevideo, on the
railway to Melo, because of the interesting stratigraphical points
that can be established there and because of the marked similarity
in the succession to that in San Juan in Argentina.

It was from the upper part of the Arroyo Fraile Muerto, at
Laguna la Tuna south of the railway that Guillemain36 in 1911 re¬
ported the presence of glacial beds. This area was examined in more
detail by Walther37 and described by him in several instructive
writings, in which use was made of the important data arising out of
borings made by the Section de Perforaciones of Uruguay, mainly
within the stretch between the pre-Gondwana rocks forming the
Cerro Largo on the southeast and the railway from Fraile Muerto to
Melo on the northwest.

36 Guillemain (1911); also (1912).

37 Walther (1919).

68 GEOLOGICAL COMPARISON OF SOUTH AMERICA WITH SOUTH AFRICA

On the Arroyo Fraile Muerto, at the Casa de Comereio belonging
to Senor Gonsalez (the Paso Tla Lucia), the basement rocks are
schistose greywaekes evidently constituting an uneven surface, over-
lain by pale sandy tillite (lower) with finely striated boulders up to
80 cm. in diameter, which, apparently following the contours of the
floor, is dipping gently northeastward, succeeded by about 1.5 meters
of shales — hard, banded, and drab in color at the bottom, and soft
and blue higher up, followed with sharp junction by the upper
tillite, a clayey material with well-striated boulders of fine-grained
quartzite, granite, gneiss, quartz-porphyry, phyllite, limestone, and
dolomite, and this in turn by hard shales, exposed along the road
leading up to the rising ground toward the east. This compound
tillite constitutes th e first and lowest glacial horizon.

The base of the glacials is not to be seen here, but is exposed
about 2 km. farther downstream, just below the homestead of Paso
de la Cruz, the foundation rocks consisting of highly tilted and folded
blue-gray limestones and dolomites with dark slaty bands — probably
lower Palaeozoic. The floor is uneven, having been cut into hollows
that do not always follow the strike of the beds, but commonly the
direction of glaciation, and not improbably owe their origin to ice
action. The tillite is in places tucked in beneath such low ridges and
at one spot is banked up against a vertical wall of limestone, where
it is crammed with lumps of that rock and is furthermore calcareous
in its matrix and rather hard. Well-grooved surfaces can be found
with the striae directed north 40 0 west (true) and though “chatter-
marks” were not seen, it was noticed that on the northwestern side
of cross- joints in the pavement flakes had sometimes been dislodged,
leaving small gaps bounded by the vertical joint on the southeastern
side, which is sharp-edged, but shallowing out on the northwestern,
where the lip is sometimes weakly striated. This, to my mind, sug¬
gests a movement of the glacier toward the northwest rather than in
the reverse direction, which will be observed to be in agreement with
that deduced in Argentina.

Whereas the rock filling the hollows is a tillite of normal charac¬
ter, its matrix gets coarser on approaching the low ridges, and, when
overlying the latter, may become a hard, coarse grit with small
boulders, many of them striated, the material arching over and
dipping at high angles toward the tillite in the hollows. The phe¬
nomena recall those to be seen in the ‘ ‘ kames * ’ of the Pleistocene glaci¬
ation, wherein a glacial sand has become molded over protuberances
of the floor beneath the ice-mass. The glacial beds are not many
meters thick hereabouts, and on passing upward the irregularities
in stratification disappear and the material grades upward into grits
and sandstones that are lying flat, though sometimes false-bedded,
and carry only small pebbles of hard rocks. Features just like these

GONDWANA SYSTEM IN BRAZIL, URUGUAY, AND PARAGUAY 69

are well known in and have been recorded from the “northern”
Dwyka of South Africa.

A few kilometers to the west, along the railway at Cerro de las
Cuentes, the basement complex displays typical roches moutonnees
on which the glacials are resting, and the sections, which I was
unable to examine in detail, should well repay study.

Returning to the account of the sections at the Paso Tia Lucia,
the shales referred to as overlying the first glacial horizon are suc¬
ceeded to the north by at least 1 5 meters of grits with very small
pebbles and by a bed of gritty stuff in which are set boulders up to
75 cm. across, well glaciated, which makes the second glacial horizon.
The homestead of Senor Gonsalez stands on this band, which, fol¬
lowed by a conspicuous sandstone, is traceable toward the east up to
the main road, a distance of fully a kilometer, while, according to the
account given by Walther38 a sandstone of this description carrying
boulders crops out between this locality and Cerro de las Cuentes
and plays an important part in the western end of the Cerro Largo
district.

At about 20 meters above this glacial band, seen at several points
to the east along the ridge which the main road to Fraile Muerto
follows and finally passing below higher strata at the Establecimiento
Quebrachal to the north, is the third glacial horizon , much thinner
and indicated only by scattered inclusions in the gritty sandstones,
mostly small and composed of hard rock, some of them certainly well
striated; lumps of silicified wood are also present in this sandstone.

Sandstones and shales follow thereon, all dipping northeastward
at 30 or 40, giving a total thickness of fully 130 meters of beds from
the floor to a horizon where first are seen the dark sandy but
“papery” shales with occasional thin limestones and silicified wood
that continue to Fraile Muerto, being well exposed in the railway
cutting to the east of the station and also pierced by a bore-hole in
the village (No. 48) to the depth of 54 meters.

These are broadly equivalent with the Iraty group and thus
furnish the datum plane from which the stratigraphical succession
can be determined. The 130 meters of beds beneath this zone cor¬
respond, therefore, with the Bonito and Itarare of Brazil, though it
is impracticable in Uruguay to draw a sharp line between the two
divisions, while even the precise base of the Iraty is a little in doubt.
I have taken the latter at the horizon where the highest of the sand¬
stones and grits is to be found; below that level the strata, as dis¬
closed by borings, consist of white, fine to coarse sandstones and
limonitic sandstones, dark shaly sandstones, sandy shales, and some
bituminous shales. All these beds that lie above the glacials will be
referred to in detail later on.

38 Walther (1919), p. 97.

70 GEOLOGICAL COMPARISON OF SOUTH AMERICA WITH SOUTH AFRICA

(2) The Boulder Beds in Brazil

Proceeding to the consideration of the “ Parana Basin” we find
the Itarare series, so called by Oliveira,39 consisting of a series of beds
of glacial origin, alternating with conglomerates, grits, sandstones,
and shales that are just like those of the succeeding Bonito or Coal
Measures, the first-named varying from unbedded, true ground-
moraine or tillite through boulder-shale to bedded shale with small
inclusions and even “pelodites” on the one hand, and through
“sandy” rocks with glacial erratics to sandstones (sometimes cross-
bedded), with waterworn pebbles (fluvio-glacial beds) on the other.
The succession, as well as the relative proportion of “normal” sedi¬
ment to glacial material, appears to vary in different parts of the
country, just as is true of the Pleistocene glacial deposits of the
Northern Hemisphere, and, while in places the top of the group is
sharply defined, as, for example, to the northwest of Jaguariahyva
in Parana, the upper limit is commonly vague, the chief criterion
being the absence higher up of any pebbly bands displaying charac¬
ters not purely fluviatile. It is obvious that in borings the upper
limit of the Itarare would often be rather indefinite, just as is the
case in Uruguay, while certain conglomeratic strata at present
mapped with the Bonito may in the future be found to be of fluvio-
glacial origin and therefore have to be placed with the Itarare.

The northeasternmost point from which this series has been
reported is in the Abaete Valley in Minas Geraes, where, according
to Rimann,40 the glacials and the succeeding “Areado sandstone”
rest upon the tilted lower Palaeozoic Bambuhy series, the existence
of the tillite in that neighborhood having long previously been noted
by D. Draper.41 This area is not improbably an outlier from the
main basin, for to the west, so far as can be gathered, the Triassic
sandstone rests directly upon mica- schists at the Agua Suja diamond
mine, and on granite between Sacramento and Franca. The tillite
appears more to the south near Mococa, is relatively thin at Monte
Santo, and runs in a widening belt southward through Casa Branca
past Campinas and Sorocaba, at the same time becoming thicker.
Excellent descriptions have been given by Woodworth42 and Cole¬
man 43 of the glacials in the region both to the northwest and west of
Campinas, while a fine photograph of the boulder-beds has been
reproduced by Branner.44

From Sorocaba the belt curves south west ward to Tibagy and
then turns abruptly southeastward past Ponta Grossa, Serrinha, Rio
Negro, and onward, the group ranging in thickness from 250 to 350
meters in Parana, but becoming progressively thinner in the direc-

39 Oliveira (1918), p. 12. 42 Woodworth (1912).

40Leme (1924), p. 178. 43 Coleman (1918), "pp. 312-317; (1926), pp. 156-162.

41 Branner (1919), p. 214. , 44 Branner (1919), PI. X.

GONDWANA SYSTEM IN BRAZIL, URUGUAY, AND PARAGUAY

tion of Santa Catherina. Woodworth’s45 detailed section of the
group between Itaicy and Piracicaba shows a huge development —
between 700 and 1,000 meters, mainly of sandy tillite and sandstone,
with at least two important partings of shales, although much of the
material can not strictly be referred to as tillite, consisting as it does
of sandstones with occasional small boulders, while similar erratics
occur in certain of the shaly bands. The succession is consequently
rather like that described by various geologists at Bacchus Marsh in
Victoria, though fossils have not yet been recorded therefrom.

The accounts by Woodworth and by Coleman of the glacials at
Jaguaricatu, Sengens, Itarare, and Ponta Grossa give a very good
idea of the variable nature of the deposits, but much of the rock,
when fresh, is actually a dark-blue massive tillite, often weathering
spheroidally, with rather small inclusions, though at times boulders
of over a meter across can be seen ; the rock thus recalls the Dwyka
conglomerate. From near the railway station of Elias Fausto, Doctor
Pacheco has reported some unusually large granite erratics, one of
them measuring fully 3 by 3 by 2 meters. The material at Ponta
Grossa, on the contrary, I found to be a yellowish soft sandstone
with only a few conglomeratic bands in which striated stones are
decidedly rare. Boulder beds in verity with abundant and large
inclusions were, however, observed between Rio Negro and Campo
do Tenente on the railway to Serrinha.

Whereas the floor beneath the Itarare is, so far as can be gathered,
rather even in the States of Sao Paulo and Parana, the features
visible at Serrinha and the description given of the glacials there by
Woodworth46 indicate an irregular floor and indeed suggest to me the
presence of a “pre-glacial” gorge in the Furnas sandstone, cut right
down into the pre-Devonian slates beneath, the northern wall of
which is made by the sandstone cliffs a few hundreds of meters from
Serrinha, along the railway to Curitiba, the hollow being filled in
with a sandy tillite overlain by a fluvio-glacial sand. The general
aspect strongly reminds me of several well-established cases of such
a kind in Natal (South Africa), where the Dwyka tillite is resting
in ravines cut in the Table Mountain sandstone and in places lies
banked against cliffs of the latter, for example, on the Umtamvuna
River near the road bridge between Izingolweni and Bizana. The
high irregularity of the pre-glacial landscape is, moreover, obvious
between Serrinha and Lapa, a little distance to the south.

The sections between Rio Negro and Canivete on the Porto
Uniao Railway reminded me very much of the Dwyka in parts of
Natal and Zululand — the blue, solid tillite, blue uniform mudstone

with hardly any stratification, and bedded blue shales. The latter,
in thickness from a few decimeters upward, run regularly for good

45 Woodworth (1912), pp. 54-61. 46 Ibid., pp. 65-66.

72 GEOLOGICAL COMPARISON OF SOUTH AMERICA WITH SOUTH AFRICA

distances and probably mark, just as they do in Natal, the temporary
cessation of morainic deposition within an estuary, but opportunity
for detailed examination was wanting. The discovery by Doctor
Oliveira of marine fossils close to Teixeira Soares on the railway
southwest of Ponta Grossa and again at Rio Negro in black shales
sandwiched between two banks of boulder shales — so far as I can
gather in the upper part of the Itarare — indicates that the ice was at
a certain stage discharging into the ocean, just as was the case with
the Dwyka ice-cap between Keetmanshoop and Mariental in the
Warmbad district in Southwest Africa. The fossils, which are as yet
undescribed, consist of small forms of Lingula , Discina , Leda (?), a
pentamerid brachiopod, a gasteropod resembling Pleurotomaria,
other indeterminable forms, scales of ganoid fishes, and wings of
insects.47

To the south of Rio Negro the Itarare is still thick — over 270
meters on the Lages-Florianopolis road — though there it includes
152 meters of beds at the base doubtfully grouped with the Gon-
dwana, but regarded by Oliveira as forming an integral part thereof.
Approaching the Tuber ao Valley the Itarare must thin rapidly, being
there represented by 32 meters of strata, of which the well-known
massive “Orleans conglomerate” forms the bulk, a stratum in which
the pebbles are sometimes from 20 to 25 cm. in diameter, and perhaps
only a local deposit. Some 2 km. below the station of Lauro Muller,
resting directly on granite, are shales enveloping a large granite
erratic which is in contact with the floor, as figured by both White48
and Woodworth.49 From this point the boundary with the granite
runs southward past Cocal and the group ends near the mouth of
the Urussanga River.

In Rio Grande do Sul, the Itarare is thin or missing between
Porto Alegre and the Uruguayan border. In the Gravatahy coal¬
field a little to northeast of Porto Alegre, according to data kindly
supplied me by Doctor Simch, the bore-holes pass directly through
shales and clays belonging to the Bonito into granite, which indi¬
cates the overlapping of the higher group on to the Carboniferous floor.
Due west of Porto Alegre, between Xarqueadas and Butia,50 a basal
conglomerate is erratically developed, resting on granite and con¬
taining large blocks of that rock; important is the section revealed
by the old Isabel shaft near Sao Jeronymo, where the 42 meters of
beds referred to as the “Orleans conglomerate” 51 include shales,
some of them dark and bituminous. Between Suspiro and Jaguary,52
on the Cacequy-Rlo Grande Railway, an unbedded gray shaly rock
1 meter thick with inclusions resting on the granite probably alone

60 White (1908), pp. 43, 47.

51 Ibid., p. 1 19.

62 Oliveira (1918), p. 27.

47 Oliveira (1918), p. 14.

48 White (1908), plate facing p. 28.

49 Woodworth (1912), Fig. 23.

GONDWANA SYSTEM IN BRAZIL, URUGUAY, AND PARAGUAY

represents the glacials, being overlain by conglomeratic sandstones,
sandstones, shales, and coals — the Bonito beds.

(3) The Boulder Beds in Uruguay

The distribution of the boulder beds in Uruguay is hardly known,
except in the vicinity of Fraile Muerto, as described above in (i),
but there can be no doubt as to the highly diversified character of
the “pre-glacial” surface in northeastern Uruguay. While the dip
of the formations is everywhere low, knobs of the crystalline floor
project through the covering of Gondwana beds at a number of places,
the surrounding strata being formed in some instances by the
Estrada Nova even. Such a granite inlier occurs along a tributary of
the Arroyo del Chuy, north-northeast of Melo, one just to the east
of that town, another to the south, forming the Cerro Verde, and two
in the Arroyo Quebrebracho to the northwest of the station of Cerro
de las Cuentas. The conspicuous Cuchilla de Cerro Largo has all the
appearance of being a glaciated range that must have remained
exposed long after the ice had disappeared and its undulating base
had become buried beneath glacial, fluvio-glacial, and normal
sediments.

The bore-hole of Zanja Honda, situated in the valley on the north¬
western side of this great ridge, passed down into phyllites at about
70 meters, the section showing several meters of blue-gray conglom¬
erate and breccia, which from the cores preserved I believe to be of
glacial origin, overlain by 14.8 meters of sandstones and these by
12 meters of the curious banded shales described by Walther53 under
Woodworth’s name of “ desmopelodite, ” and which, from their
alternating light and dark laminae of differing texture (in thickness
from 12 down to below 1 mm.), have been compared with the
seasonally banded glacial clays of the Pleistocene. Similar beds were
described by Guillemain at Laguna la Tuna in the head of the
Arroyo Fraile Muerto, which not improbably correspond with the
“inter-glacial” shale parting in the lowest glacial horizon at Paso
Tia Lucia a short distance farther down the valley. These shales were
obviously laid down in tranquil water (limno-glacial deposits) and
display on their faces what are supposed to be crustacean tracks. If
the 33 meters of strata at Zanja Honda immediately above them
represent the Iraty, as stated by Walther, though this with good
reason is doubted by Arocena,54 then a great overlap has taken place
within a distance of 25 km. with the suppression of the Bonito, which,
taking into account the physiographical conditions that must have
been present, would not be altogether unexpected.

While Walther ’s account55 shows that coarse sandstones with

53 Walther (1919), p. 91 and PI. X. 65 Walther (1919), pp. 97-98.

54 Arocena (1926), p. 5.

74 GEOLOGICAL COMPARISON OF SOUTH AMERICA WITH SOUTH AFRICA

boulders, possibly the second glacial horizon, play an important role
to the west of Cerro de las Cuentas, so far west indeed as the Arroyo
Cordobes, and while glacials have recently been discovered in the
region immediately beyond, it would appear that a little to the north
of Durazno the Triassic has overstepped the lower series. As regards
the deep boring at Tacuarembo,59 it is just possible that glacial beds
here form an important group, my examination of the cores showing
that from 310 meters downward they are perhaps as much as 40
meters thick, including a dark gray clayey rock and a pale gray gritty
material with grains of quartz and rock fragments, passing down at
about 349 meters into a typical tillite containing pebbles of granite
with the granitic basement struck at about 350 meters. No similar
rocks have yet been noticed at the base of the system shortly toward
the east along the Tacuarembo River, where again the Triassic
appears to transgress on to the basement.60

It is unfortunate that so little should be known about the north¬
western side of the Parana Basin. No glacials have yet been reported
from Paraguay or southern Matto Grosso, though they are known to
occur close to Rio Bonito in the southern part of Goyaz, resting
apparently on the Devonian, and not unlikely are present in the
upper part of the Parnahyba Valley also.

(4) The Position of the Glacial Center

Although the rounded granite surfaces recorded close to Campi¬
nas in Sao Paulo do not bear any definite striae, and roches moutonnies
have not been recorded elsewhere in Brazil, a certain amount can be
deduced regarding the probable position of the Carboniferous glacial
center from the inclusions in the tillite of Sao Paulo and Parana.
Coleman 61 has mentioned erratics of a peculiar coarse conglomerate
near Capivary containing pebbles of brilliant red jasper derived from
some ancient formation unknown in the country, and which I have
elsewhere remarked are very like those found in the Dwyka of
Southwest Africa that must have been derived from the Matsap
series of Griqualand West lying hundreds of kilometers to the east.
Recently, however, Dr. L. C. Ferraz 62 has recorded a practically
identical conglomerate in situ far to the south, in the Morro Bahu,
on the north side of the Itajahy River close to Blumenau, in Santa
Catherina, which, if not the source of the blocks in question, would
indicate at least the likelihood of a southerly origin.

Furthermore, Woodworth63 has drawn attention to certain inclu¬
sions of fine-grained white sandstone (whetstone), which are indica¬
tive of an easterly derivation. In Uruguay, as has been pointed out,
the center seemingly lay toward the southeast, and a similar direc-

69 Walther (1919), p. 100. 61 Coleman (1918), p. 314. 63 Woodworth (1912), p. 63.

60Arocena (1926). 62 Ferraz (1921). • .

GONDWANA SYSTEM IN BRAZIL, URUGUAY, AND PARAGUAY

tion is prompted by the Argentine occurrences, all of which suggest
an area lying out in the present Atlantic, and with which the sporadic
development of the glacials and the overlapping of the higher beds on
to the crystallines in the extreme south of Brazil would appear to
support. A certain amount of speculation on this problem will be
indulged in later on.

(5) The Tuberao Series

Doctor Oliveira has restricted the name Tuberao series to the
strata above the Orleans conglomerate or the Itarare glacials,
namely, to the Bonito group below and the Palermo group above, the
former about 180 meters thick, the latter about 80 meters, or 270
meters in all.

The Bonito consists of soft, yellowish and grayish-white sand¬
stones, sometimes in massive beds, interbedded with bluish or gray
and occasionally micaceous shales, often plant-bearing; conglomer¬
ates are rare and thin. Important is the occurrence therein in Brazil
of seams of coal upon at least five horizons that are identifiable over
pretty wide areas. The workable seams are those of the Bonito coal
about midway in the succession and the Barro Branco or Sao Jero-
nymo coal near the top ; partings of shale are general, and the coals
are always high in ash and often extremely pyritic. They are well
developed in the Tuber ao-Treviso area in Santa Catherina and again
along the Jacuhy Valley west of Porto Alegre in Rio Grande do Sul,
while coals have also been proved at intervals on the Rio Grande
Railway, such as at Suspiro, Rio Negro, Candiota, and between
Cerro Chato and Sao Jo ao do Herval down to the Uruguayan border,
and also in the opposite direction in the belt west of Ponta Grossa and
Tibagy in Parana and on the Rio das Cinzas northwest of Itarare.
A wealth of detail is to be found in the monumental report of the
Brazilian Coal Commission64 and in the supplementary memoir
by Doctor Oliveira.65

The Palermo group is formed mainly of soft shaly beds of a gray
or blue color (though red tints have occasionally been observed in
Parana) and passes up without a break into the Iraty shales. It is
marked off from the Bonito in Brazil by a calcareous horizon with
large nodules of chert, while silicified wood of the genus Dadoxylon
is common, but the group is difficult to delimit in Uruguay.

It might be noted that in two areas where coals are locally
developed in the basal part of the Bonito,66 a thin seam rests directly
upon the top of the tillite forming part of the Itarare, for example, in
the valley of the Rio das Cinzas and at Butia to the southwest of Sao
Jeronymo, and seemingly also near Suspiro on the Rio Grande Rail¬
way, thus recalling to some extent the features to be seen at Vereenig-

66 Oliveira (1918). 66 Ibid., pp. 34, 103.

64 White (1908).

76 GEOLOGICAL COMPARISON OF SOUTH AMERICA WITH SOUTH AFRICA

ing in the Transvaal, where the Ecca coals may rest directly upon
either tillite or pre- Devonian dolomite.

It is further interesting to observe that the Tuber ao series, when
followed northward into the State of Sao Paulo, where it is termed
the “Tatuhy ” by Doctor Pacheco, is largely made by greenish sand¬
stones, and that coals are absent, save for a seam at Jacuha, 20 km.
southwest of Campinas, overlain by a boulder bed supposed by him
to be of glacial origin, but which is supposed by others to be remanie,
as in the succession at Vereeniging. Between Limeira and Rio
Claro, in Sao Paulo, the Tatuhy, followed by the Iraty, has become
quite thin.

In the opposite direction the Gondwana beds make a basin near
the Uruguayan border and the Tuber ao is found to the south of the
Jaguarao River,67 where, in three bore-holes at least, 92 meters of
beds were proved beneath the Iraty group with Mesosaurus , dis¬
closing a seam of impure coal 1 meter thick that probably corresponds
to one of the upper coals of this series in Brazil. This being the first
locality in Uruguay where coal was struck, borings were thereafter
undertaken at a number of points in the Department of Cerro Largo
and also at Tacuarembo — the sections of which have been detailed
by Walther68 — but without success, from which it would appear
that the limit of the area characterized by the coal-bearing facies of
the lower Gondwana has been reached somewhere about Melo,
though I am inclined to agree with Walther that the borings at
Buena Vista and Isla de Zapata were stopped too soon. The boring
in the town of Melo showed no less than 301 meters of strata ascri-
bable to the Tuberao without the crystalline floor being reached,
though it is not improbable that toward its base fluvio-glacial beds
like those described from Fraile Muerto were actually cut.

It is undoubted that to the southwest of Melo the thickness of
strata decreases considerably, which is in great part due to the
uneven character of the floor upon which the beds repose, as proved
by the isolated inliers of granite in the midst of the nearly horizontal
sediments, as already referred to. The equivalent of the Palermo is
more arenaceous than in the coal-fields of Brazil, making it practic¬
ally impossible to separate this group from the Bonito. The same is
the case to the west, the Tacuarembo boring exhibiting only 84
meters of strata between the Iraty and the granite, of which perhaps
only just over one-half can be relegated to the Tuberao (Bonito
and Palermo).

Westward in Argentina the Bonito is apparently represented in
the San Cristobal bore-hole in Santa Fe at between 1,140 and 1,384
meters, some of the sandstones being reddish, like the Paganzo, a
feature still more marked in the Tostado bore-hole (1,600 meters) to

67 Walther (1919), pp. 92-93. 68 Ilid., pp. 99, 100; see also (1924).

GONDWANA SYSTEM IN BRAZIL, URUGUAY, AND PARAGUAY 77

the northwest, but the strata in the Alhuampa bore-hole, from 1,700
meters down to 2,100 meters, are whiter again.

Our knowledge concerning this series on the northwest and north
of the basin is of the scantiest. Information given me by Doctor
Beder and an examination of the specimens collected by him in
Paraguay show that carbonaceous shales occur about Santa Maria to
the west-northwest of Posadas and grits, sandstones, conglomerates,
and carbonaceous shales like those of the Bonito at Paraguary close
to Asuncion and similar strata at Villa Hayes, a little above that
town, on the right bank of the Paraguay River, the latter consti¬
tuting the only solid rock exposed in the broad alluvial plain west of
that river.

(6) The Flora of the Bonito Group

D. White 69 and G. Lundqvist 70 have materially added to Zeiller’s
original description, while the former has also made it clear that the
plants occur on various levels from almost immediately above the
Orleans conglomerate upward. Those from the lower part of the
group in striking fashion consist solely of typical members of
the southern flora, such as Gangamopteris cyclopteroides {G. obovata
White), Glossopteris browniana, Cordaites hislopi , Phyllotheca gries-
bachi and P. muelleriana, but on a higher horizon in association with
Glossopteris indica, G. ampla , G. occidentals, and on some unknown
level Neuropteridium validum and Annularia australis, appear
Lepidophloios laricinus, Sigillaria brardii, Lepidodendron pedro-
anum, Sphenophyllum oblongifolium, Pecopteris spp., and perhaps
Lycopodiopsis derbyi, though the last is regarded by White as a
southern form.

It is instructive to observe that in western Argentina these latter,
as well as other northern Carboniferous forms, appear to have been
found, together with the southern types, in the lowest stage of the
Paganzo, so that in Brazil these “exotic” forms make their entry at
a somewhat later date apparently. In South Africa they entered at
a later period still during the Ecca, subsequent indeed to the deposi¬
tion of the Iraty group. It is to be hoped that further systematic
collecting may be undertaken to afford additional information on this
important question. These observations rather lessen the probability
of White’s 71 supposition that those northern forms were able to pene¬
trate the region only because of a progressive amelioration of
the climate.

In making age determinations we have to eliminate the prepond¬
erant southern element as being of no direct value, though of course
that assemblage is closely related to the floras of the equivalent
Talchir-Karharbari series of India, the Greta Coal Measures of New

69 White (1908), pp. 361-373; also (1907), p. 617. 71 White (1908)^.399.

70 Lundqvist (1919).

78 GEOLOGICAL COMPARISON OF SOUTH AMERICA WITH SOUTH AFRICA

South Wales, and the Ecca Coal Measures of South Africa. Con¬
sidering merely the northern forms, the five just mentioned, together
with Samaropsis {Car diocar port) bar cello sa are all identical with or
very closely related to typically upper Carboniferous species , and in
my opinion form useful confirmation for a pre-Permian age, such as
has been arrived at from other considerations, though this view
differs radically from the conclusions reached by D. White and
certain others.

(7) The Passa Dois Series

This embraces the Iraty, some 70 meters thick, below', and the
Estrada Nova (or Corumbatahy) , fully 150 meters thick, above, two
groups that are extraordinarily constant throughout the basin,
though not yet recognized in central or western Argentina.

The Iraty group 72 is composed chiefly of black, carbonaceous, and
often “papery” shales, in places pyritic, and which on being freshly
broken may give out an odor of petroleum ; small veins of bituminous
matter — albertite or grahamite — are sometimes to be found. On
weathering they bleach to pale bluish, and finally to white or faintly
pink, flaky clay shales with secondary gypsum, exactly as in the case
of the “White band ” of the Dwyka shales. Characteristic are nodules
of chert and thin layers of limestone (particularly toward the base),
sometimes fibrous in structure.

In Uruguay the shales are not so argillaceous, while thin bands of
white sandstone and darker micaceous sandstone are also present,
making it difficult to delimit the group from the “Palermo ” beneath,
which fact explains the excessive value given by Walther for its
thickness, though such figure must certainly exceed 100 meters. In
Paraguay the beds are also more arenaceous. On the other hand,
the group becomes more calcareous to the northeast, and in the
neighborhood of Rio Claro in Sao Paulo, white and gray fine-grained
crystalline limestones play an important part, being actually quarried
as a source of lime.

The group is traceable from Palmeira in that quarter southwest-
ward, making a sweeping curve through Parana that passes 60 km.
to the west of Tibagy and then turns east of south through Iraty to
Lauro Muller and thence to the Atlantic coast. Possibly overlapped
just a little to the northeast of Porto Alegre by higher divisions, the
Iraty has been proved by occasional outcrops and by borings along
the southern side of the Jacuhy River, running nearly due westward,
passing to the north of Sao Sepe and thence through Sao Gabriel,
after which its exact course is not known with certainty, but it is
exposed on the Uruguayan border between Paso Maria Isabel and
Paso Minarano, and turning southwestward stretches along the base

72 White (1908), pp. 181-191; Oliveira (1918), p. 16.

GONDWANA SYSTEM IN BRAZIL, URUGUAY, AND PARAGUAY

of the Cerro Largo and, curving through Fraile Muerto, strikes west-
northwestward toward the Rio Negro. It was cut in the boring at
Tacuarembo beneath the Triassics and is known to reappear on the
farther side of the basin at Villarrica in Paraguay, where fossil bones
occur, while Millward has reported the extension of this and the
Estrada Nova in the south of Matto Grosso and Goyaz, apparently
from the foot of the Sierra de Aquidauana northeastward past Rio
Bonito to Rio Verde, but this quarter is as yet only slightly known.

Fossils — Important is the frequency with which the singular
little reptile Mesosaurus has been found at various points along the
known huge extent of outcrop within certain layers in the black
shales. In places the shales are just crowded with skeletons and in¬
deed, not infrequently, such remains are discovered in bore-hole
cores. Along with it occurs the very closely allied but generally
larger form Stereo sternum, though curiously it is stated that the latter
is practically confined to the limestone layers. Some splendid show
specimens of both these reptiles, and of Stereosternum embedded in
white limestone, are displayed in the State Museum at Sao Paulo.

It is essential to observe that long ago Lydekker, and recently
that high authority Von Huene,73 have refused to recognize the gen¬
eric status of Stereo sternum, both regarding it as a species of Meso¬
saurus, and for the present we shall therefore consider them as
Mesosaurus tumidus and M. brasiliensis respectively. Von Huene,
reviewing the known South African species, has furthermore placed
them all in the one form, M. tenuidens, with the opinion that the
latter is probably distinct from the two species represented in Brazil.
Noteworthy is the fact that this unique creature — clearly a free-
swimming reptile — has as yet been found only in the Parana basin
and not elsewhere in South America, although strata of equivalent
age are certainly represented elsewhere in that continent, while
across the Atlantic it has been recorded at intervals from the
Kaokoveld in Southwest Africa down to the south of the Karroo,
though not to the east or northeast (see Fig. 7, on which the approx¬
imate limits are indicated).

Walther has mentioned the finding on the Rio Jaguar ao in north¬
eastern Uruguay of impressions resembling those described by White
from the Bonito of Santa Catherina under the name of Hastimima,
originally thought to be a plant, but later discovered to belong to an
eurypterid. Doctor Pacheco has informed me of the occurrence in
Sao Paulo State of Schizodus (?), while Broili in a letter to Walther
has identified certain fish-scales from the boring at Isla de Zapata near
Melo as belonging to a ganoid. Not improbably the fossil wood
Dadoxylon pedroi Zeill. comes from the Iraty of Sao Paulo. Derby has
furthermore remarked upon the association in Sao Paulo State — an

73 Von Huene (1925), pp. 118-120.

80 GEOLOGICAL COMPARISON OF SOUTH AMERICA WITH SOUTH AFRICA

important one — of Psaronius with Stereosternum and Lycopodiopsis
derbyi , and the latter has been discovered even above the Iraty
group.74

Just as in the Cape Province with the shales of the White band,
so the bituminous nature of the Iraty shales has led to much pros¬
pecting for coal, while their petroliferous odor when broken has
incidentally been responsible for the drilling of several deep bore¬
holes in search of oil; in both countries, it might be remarked, the
shales are often sapropelitic in character and will furnish oil on
distillation.

The exclusive presence of Mesosaurus and the outstanding litho¬
logical similarities, down to minutiae, render the correlation of the
Iraty group with the White band of the Dwyka series absolutely assured ,
although a distance of 6,300 km. separates their nearest outcrops,
whereas these two zones are traceable not more than 1,000 km.
away from the Atlantic shore in either case.

(8) The Estrada Nova Group

The Estrada Nova group, or, as it has been called in Sao Paulo,
the Corumbatahy group, follows the Iraty with seeming conformity
from just south of Palmeira in that State to Tacuarembo in Uruguay,
an assemblage that seldom has good exposures, crumbling readily
and so releasing the cherty concretions that form so characteristic
a feature of it.75

The beds are arenaceous shales — gray, dark greenish or reddish,
pink, lavender or lilac — always well-laminated, with intercalated
bands of relatively pure sandstone very rich in siliceous nodules, and
nodules of chert, together with some white limestone. While most
of the bright coloration is certainly due to weathering, some of it is
original, as borings have proved, and the superficial pink, heliotrope,
or lilac tints help materially to distinguish this group from the lower
division, although proving a source of trouble when attempting to
discriminate it from the succeeding deeply colored strata. Taken
by I. C. White as the top of this group, because it was overlain by the
Triassic Rio do Rasto series, is the Rocinha limestone, a band attain¬
ing the maximum thickness of 3 meters, though only rarely exposed,
and known along the Rio Rocinha in Santa Catherina, at Therezina
in Parana, and Fartura in Sao Paulo, but which is supposed to be
represented at other points by cherty beds with fossil mollusca.76
The thickness of the group is taken as 150 meters, but the inclusion
of certain higher beds in Parana that can be placed in the Estrada
Nova would bring up the value in that State to fully 300 meters.

The Estrada Nova is important because of its fossiliferous charac-

74 White (1908), p. 371.

75 Ibid., pp. 191-195.

76 Oliveira (1918), p. 17.

GONDWANA SYSTEM IN BRAZIL, URUGUAY, AND PARAGUAY

ter, indicative of deposition in an estuary with occasional incursions
of the ocean. At Rio Claro, east of Marechal Mallet Station in
Parana, mollusca have been found in the cherts and siliceous oolites
(Zone i) and also at a slightly higher level in a calcareous sand¬
stone (Zone 2), these two fossiliferous horizons having been recog¬
nized at several other points to the west of the railway between
Marechal Mallet and Iraty, these occurrences having been detailed by
Oliveira and certain of the forms described by Holdhaus. 77 (See below.)

The sequence that I was able to examine between Marechal
Mallet and Rio Claro is a rather important one. In the first bore-hole,
situated 4 km. to the west of Rio Claro, there are fully 200 meters
of beds — bluish-green shales with white calcareous and sandy well-
banded layers — overlying the Iraty group. The soft fossiliferous
sandstone with “Solenomorpha ” etc., taken by Oliveira as the top of
the Estrada Nova, crops out about 40 meters higher still, yet above
the latter the rising ground on the road to Marechal Mallet displays
for a vertical distance of 40 meters similar strata, except for the
absence of cherts. Above this the beds become more arenaceous, yet
not until nearly 75 meters above the “ Solenomorpha ” band do strata
make their appearance, having strong red coloration, from which
point red and purple sandstones and mudstones are visible, followed
by buff fine-grained sandstones and greenish mudstones and shales,
with intrusions of dolerite up to the summit of the Serra do Tigre.

The upper portion of these 300 meters of beds overlying the Iraty
could preferably be included in the Estrada Nova, despite the
absence of cherts, the higher strata with bright-colored shales and
mudstones being allotted to the Rio de Rasto.

In Rio Grande do Sul this group has nowhere been mapped, but
in Uruguay, entering from Brazil, it is known to run southward
down the Canada de Ibanez past Melo and a little to the north of
Fraile Muerto and thence northwestward across the Rio Negro and
up the Tacuarembo Valley, covering a wide area to the south and
east of the town of that name. It is also known to surround much of
the granite inlier of the Department of Riviera.

The only place where I was able to study these beds in Uruguay
was in the shallow basin crossed by the railway between Fraile
Muerto and Melo, where, proceeding from the former station, the
laminated olive and buff clayey shales with ribs of sandstone and
limestone belonging to the Iraty pass up at kilometer 390 into
greenish, lavender, and then into red, carmine, and white laminated
beds, with thin layers of white cherty rock, and are hence very like
the Corumbatahy group of Sao Paulo. Between kilometers 392 and
393 some red sandstones appear, and, though the well-laminated
character of the shales persists for a short distance, the beds give way

77 Holdhaus (1919).

82 GEOLOGICAL COMPARISON OF SOUTH AMERICA WITH SOUTH AFRICA

to a group of less well bedded red and variegated clays and mud¬
stones and red sandstones somewhat evenly stratified, sometimes
cross-bedded, as at 395. At kilometer 400, just before reaching
Banado de Medina, a thick sandstone of this kind rests on red clays,
and such arenaceous beds extend almost to Melo and occupy a con¬
siderable area to the north and northwest. All the rocks from about
kilometer 394 onward can, I think, be taken as representing the Rio
do Rasto group. The bore-hole at Buena Vista, 20 km. north of
Melo, reveals a similar sequence with about 245 meters of strata
ascribable to the Estrada Nova, while Walther states that to the
south of Melo siliceous concretions have weathered out from these
beds in great numbers.

In Paraguay, according to Beder,78 there are at Villarrica, in addi¬
tion to the undoubted Iraty cherts, some with oolitic structure and
also some higher reddish friable sandstones that have yielded species
of “ Solenomorpha .” According to Leme,79 Millward has found in the
south of Goyaz similar beds with plant fossils and lamellibranchs,
presumably belonging to this group and covering a wide area round
about Rio Bonito and Jatahy and thence southwestward towards
Aquidauana on the railway to Porto Esperanga.

(9) The Fossils of the Estrada Nova

The stratigraphical position of the Estrada Nova is at the
moment involved, as this so-called “group” would appear to include
beds of rather different ages. Of the lamellibranchs that occur at
a number of points in Parana, Holdhaus80 has described several
species of Solenomorpha and one of Sanguinolites , maintaining a
Permian age for the formation. Dr. Reed, who has determined the
mollusca collected by me from Zones 1 and 2 at Rio Claro, doubts
Holdhaus ’s identifications, having discovered in these two horizons
only Trias sic forms, such as Pachycardia, Anodontophora , Myophoria ,
and Schafhautlia, as detailed on page 150.

Although the sequence has hitherto been regarded as an
unbroken one, a stratigraphical hiatus must he present , though the
precise plane thereof has not yet been located in the field. Any
beds below this surface of discontinuity must lie conformably upon
the Iraty and hence belong to the Permian ; those above it being of
Triassic age, must perforce be associated with the overlying Rio
do Rasto and are presumably conformable therewith. Future
work will no doubt bring about a better re-arrangement of the
Estrada Nova.

Fish scales and bones have been discovered, also silicified wood has
been determined by D. White as Dadoxylon nummularium, a species
in which no annual rings can be made out, though Walther has found

78Beder (1923), p. 11. 79 Leme (1924), p. 179. 80 Holdhaus (1919).

GONDWANA SYSTEM IN BRAZIL, URUGUAY, AND PARAGUAY 83

other kinds in Uruguay in which the rings are perfectly well defined.
At kilometer post 124 on the railway, 17 km. south of Iraty, I
obtained a fragment of Glossopteris , while, from near the top of the
group in the area between Marechal Mallet and Roxo Roiz, Zeiller 81
has determined Glossopteris browniana , G. angustifolia, Txniopteris
possibly T.feddeni, Pecopteris sp., Cladophlebis sp., and equisetaceous
stems. A frond in the Geological Survey Museum, Rio, labeled
“Glossopteris” belongs probably to the Triassic genus Sagenopteris.

(10) The Triassic Overlap

Before proceeding to the description of the higher groups, it will
be proper to discuss this particular question because of the light
which it sheds on the succession, more particularly in Parana.

Evidence, palaeontological as well as stratigraphical, has gradu¬
ally been accumulating, as can be found on perusing the writings of
Walther, Baker, and others, to show that a break must exist within
the Parana basin between beds that are certainly Triassic and those
that are definitely Permian or older, thus tending to bring the strati¬
graphy of this part of the continent into harmony with that of western
Argentina. Future work will have to be directed toward the mapping
of the “ disconformity , ” but the gap, so far as can be made out,
seemingly represents the whole of the uppermost Permian and perhaps
much of the lower Triassic.

In the north of Sao Paulo the Triassic Botucatu sandstone reposes
on the ancient floor of schists near the Agua Suja diamond mine and
at Franca, while farther south, at Monte Santo the Pyramboia — the
equivalent of the Rio do Rasto — rests directly upon the Itarare
tillite. West of Mococa, on the border of Minas Geraes, Doctor
Pacheco informs me that the lower groups have suffered some flexing,
which action may have been due to inter-Triassic earth-movements.
At Palmeira the Pyramboia rests on the Iraty, and farther south on
the Corumbatahy or Estrada Nova, which relationship, so far as
can be gathered, thenceforward holds good into Santa Catherina,
though the latest geological map of Parana (1925 ; scale 1 : 1,000,000)
by Doctor Oliveira makes the Rio do Rasto transgress across the
Itarare and Passa Dois in the vicinity of Thomazina. In Santa
Catherina, I. C. White observed the contact with the Rocinha lime¬
stone to be an unconformity over the short length exposed.

The Rio do Rasto extends on the coast from Morro Conventos
(lat. 2 90) to Conceiao do Arroio and thence westward to the north of
Porto Alegre, but according to information from Doctors Rego and
Lofgren this formation also builds the large hill to the east of that
town and stretches past Vumiao into the Serra Geral ( not the great
range of that name in Santa Catherina), immediately to the east.

81Holdhaus (1919), p. 30.

84 GEOLOGICAL COMPARISON OF SOUTH AMERICA WITH SOUTH AFRICA

It is not improbable, judging from the height to which the granite
rises at Porto Alegre, that the Rio do Rasto overlaps across the
Bonito group of the Gravatahy coal-field to come to rest on the gran¬
ite in the south. Proceeding up the Jacuhy Valley, with its exten¬
sive alluvial plains, shales regarded as Iraty were observed by Doctor
Rego, 3 km. west of Rio Pardo, the beds round about belonging to
the Rio do Rasto. The deep boring at Ferreira, however, close to
Cachoeira, which I saw in progress, proved the Rio do Rasto, down
to 73 meters at least, with the Estrada Nova (including a 30-meter
sheet of dolerite) beneath and the top of the Iraty at 260 meters.

While the Tuber ao and Iraty make a sweeping curve around the
granite axis in the country between Sao Sepe and Bage, followed
farther to the north by the Rio do Rasto in regular fashion, Wal-
ther’s 82 observation of an area at Cagapava made by the Triassic
resting directly on the crystallines is of great importance. Between
Cagapava and the Seibal Copper Mine the sediments are only from
6 to 8 meters thick, with a red basal conglomerate, and are covered
by highly vesicular amygdaloids, presumably the equivalents of the
Serra Geral eruptives. At Sao Sebastiao, on the railway to Bage,
another outlier occurs.

Over much of Uruguay, just as in Brazil, the Rio do Rasto has
not yet been carefully delimited from the top of the rather lithologic¬
ally similar Estrada Nova, and a pseudo-conformity probably exists,
as, for example, in the Department of Cerro Largo, the younger group
being distinguishable by the predominance of red sandstones, often
massive and cross-bedded. But in the important section described
by Walther 83 in the Cerro Mirinaque east of Tacuarembo, 80 meters
of these arenaceous red beds rest directly on the granite, whereas at
Tacuarembo, where such strata compose both the plain and the
neighboring spurs, the rocks cut in the deep boring embrace the
whole of the Iraty and Tuber ao. Examination of the core leads me
to believe that the bright cream, red, and brown sandstones, gritty
at their base, are here 126 meters thick and rest upon 24 meters only
of maroon and heliotrope mudstones that can be ascribed to the
Estrada Nova and these in turn upon the Iraty, etc. The overlap is
also discovered far to the south, nearly 100 km. away from the main
basin, where, on the Barrija Negro in the Minas district, Walther84
has recorded, resting upon the crystal lines, gray, yellow, and dark-
red ripple-marked sandstones, coarse conglomerates, etc., overlain
by vesicular basalt. Boring No. 51 in the soil-covered region at
Santa Rosa on the Melo Railway, 55 km. from Montevideo, proved
red and chocolate-colored amygdaloid down to 78 meters at least,
and, after piercing some softer rock beneath, penetrated a red con-

82 Walther (1912) and (1912a).

83 Ibid. (1919), p. 1 12.

84 Ibid. (1912), p. 401.

GONDWANA SYSTEM IN BRAZIL, URUGUAY, AND PARAGUAY 85

glomerate with boulders of gneiss, grits, quartzites, etc., down to in
meters. The red gritty sandstones at Sauce, however, appear to me
to be probably of Cretaceous or Tertiary age.

From the record of the San Cristobal bore-hole85 in Santa Fe,
Argentina, the Rio do Rasto apparently rests on the Bonito at about
1,140 meters, the Iraty not being identifiable, while that at Galeguay
in Entre Rios east of Rosario shows beneath 463 meters of Neogene
36 meters of volcanics (fine-grained porphyrites) resting directly
upon amphibolite without any Botucatu. According to Leme, the
transgression is again to be found far to the northwest, where, on the
west side of the basin at Aquidauana, the Botucatu followed by vol¬
canics reposes upon schists.

These various and isolated observations, though scattered over
an enormous area, collectively justify our concluding that the Rio do
Rasto must in a number of places, chiefly be it noted on the margins
of the basin, overlap and be unconformable to the lower groups, thus
forming a parallel to the Karroo system. Within the basin, however,
the molluscan horizons (Triassic) would prove that this plane of
overlapping is there situated somewhere within the limits of the
Estrada Nova as correctly defined, presumably nearer its base,
these marine beds being elsewhere overstepped by the continental
Rio do Rasto. The tracing out of this break will be an important
investigation for the future. The circumstances in the Parana basin
would seem to form an almost exact parallel to those in the north of
the Orange Free State in South Africa, where, by the dying out of
the Molteno beds, two maroon and mainly argillaceous formations
are brought together, the upper Triassic Red beds coming to rest
directly upon the lower Triassic upper Beaufort beds in that area,
but in the central Transvaal upon the lower Permian Ecca beds
generally.

Attention can also be drawn to the transgression of the Trias-
Rhastic (Stage IV) in Argentina across Stages III, II, and even I of
the Paganzo, as detailed earlier,86 of which Stage II displays many
points of lithological similarity with the Passa Dois series. In the
Parana basin, however, unlike the pre-Cordilleran region, the older
groups were only slightly warped and eroded during the early
Triassic.

(11) The Sao Bento Series — Triassic

In the Parana basin this is divided into :

3. Serra Geral eruptives, up to 500 meters in thickness

2. Botucatu sandstone _ o to 100 meters in thickness

1. Rio do Rasto beds ... 100 to 400 meters in thickness usually

This arrangement, it will be observed, differs slightly from the
scheme proposed by I. C. White.

85 Hausen (1919), p. 35.

86 Section F (5) .

86 GEOLOGICAL COMPARISON OF SOUTH AMERICA WITH SOUTH AFRICA

The placing of the lowest of these devisions in the Permian, as has
been done by Oliveira,87 has nothing to support it, since the mollus-
can remains found beneath it belong to undoubtedly Triassic forms.

The beds again with vertebrate fossils while overlapping the
older groups in certain places, pass without a break into the Botu¬
catu, where that division is recognizable, overlain in turn by and
intimately associated with the basic lavas or “traps. ”

The Triassic occupies a huge region — the greater part of the
basin in fact — for which the volcanic group is mainly responsible
areally. In places it is unconformably covered by patches of the
Bauru (Cretaceous) beds, while to the west the succession passes
beneath the Neogene of the lower Parana River, though whether
some faulting has been responsible for its lower position in that direc¬
tion is not yet assured.

(12) The Triassic Continental Sediments

The Rio do Rasto ,88 also called the Pyramboia group in Sao
Paulo, is so closely associated with the Botucatu (or Sao Bento)
sandstone, that the two groups must be described together. Appar¬
ently only in the south of Parana and in Santa Catherina, according
to the account of White, is the upper division well differentiated and
clearly distinguishable from the lowrer ; in Rio Grande do Sul it is in
places not clearly separable, while over much of Uruguay the paler
color of the top of the sedimentary formation is largely a secondary
character. The term Botucatu, furthermore, seems to have been also
used by the Geological Survey of Brazil for the sedimentary inter¬
calations between the lavas.

The friability of the lower red sandstones and mudstones,
coupled with the hardness of the overlying Botucatu or the traps,
has been responsible for an escarpment traceable nearly right around
the basin, this feature being bordered by many picturesque outliers,
from table-topped to conical. To a wonderful degree the rocks and
scenery recall the “Basalt-Cave sandstone — Red beds” topography
around Basutoland or in the Kaokoveld and parts of southern Rho¬
desia. The development in Santa Catherina is from all accounts
most like that of Basutoland and the features seen elsewhere like
those in Rhodesia.

The Rio do Rasto or Pyramboia consists of friable red, often
vivid, sandstones with occasional white blotches often false-bedded
on a large scale; layers of fine-grained pink, red, purplish, and occa¬
sionally greenish clays are also present, but there is not the well-
marked lamination and alteration of shales and thin sandstones
characteristic of the Estrada Nova, while the diagonal bedding in
the sandstones is also most conspicuous.

87 Oliveira (1918), p. 11.

88 White (1908), pp. 197-21 1.

GONDWANA SYSTEM IN BRAZIL, URUGUAY, AND PARAGUAY 87

At Taquara, north of Porto Alegre, where the upper part of the
brown -red sandstones was of uniform character through a thickness
of fully 75 meters, I found the false-bedding most pronounced, the
planes often dipping at angles up to 40 ° from the horizontal in
opposite directions in surprising fashion through individual thick¬
nesses in some places of 1 2 meters or more of rock. The sandstone is
quarried for paving slabs (Plate XII, B ), being built up of alternate
laminae of fine-grained rather clayey material and coarser, friable
“millet seed” grains in strictly parallel fashion and not in lenses;
mica is practically absent, but iron ores are abundant and a cal¬
careous matrix is indicated. In the coarser bands not only the grains
of quartz, but even those of feldspar (which are quite fresh), are
well rounded, and up to a millimeter in diameter, and there can be
no doubt that this formation is of eolian origin. The same was found
to be the case about Sant’ Anna and Riviera, on the border of Uru¬
guay, the smaller grains tending to be subrounded. Doctor Pacheco
informs me that the sand grains in the Pyramboia of Sao Paulo are
well rounded, each coated with a thin pellicle of iron oxide.

In the basal part of the group, as seen along the railway between
Porto Alegre and Santa Maria and again between Rivera and Tacua-
rembo in Uruguay the sandstones become fine-grained and pass
into mudstones of uniform nature and wonderfully brilliant hue
wherever freshly exposed, while irregular calcareous patches are
common. Crumbling readily, they give rise to sandy or loamy soils
of wide distribution, from which the red tint has been removed by
bleaching. What were considered to be the basal beds were cut in
the Tacuarembo boring at 126 meters and were coarser and gritty.
Some curious veins or reefs, within which the sandstones have been
partially or wholly silicified, are frequent in northern Uruguay, as
described by Walther; from examination of two of these near Paso
del Cerro it seems not improbable that they have been produced by
heated waters descending through fissures from the lavas above.

In the northeastern part of Paraguay the red sandstones inter-
bedded with and capped by basalts occur at Bella Vista and build
the Sierra de Amambay, while they extend northeastward from
Aquidauana into Goyaz and onward, with a large outlying area to the
northwest in the Chapada.

The thickness of the group must be considerable; at least 400
meters between Taquara and Santa Maria, but less than half that in
Parana, Santa Catherina, and Uruguay, and according to Baker89
under 100 meters in the north. In the San Cristobal bore-hole it is
perhaps 240 meters thick.

The Botucatu sandstone is a little coarser and paler, generally
creamy or gray, though sometimes terra-cotta or red, and then hard

89 Baker (1923), p. 68.

88 GEOLOGICAL COMPARISON OF SOUTH AMERICA WITH SOUTH AFRICA

to distinguish from the underlying Rio do Rasto, particularly as it
tends to display the same conspicuous false-bedding. Pacheco states
that in Sao Paulo the grains are usually angular, but at Ityrapina
I found the sandstones, with which basalt flows are interbedded, to
be pinkish, gritty though friable, with quartz grains up to 3 mm. in
diameter, many of them oval or spherical, while the bulk were sub-
angular and not angular. Here the group was over 200 meters thick.

In Parana and Santa Catherina the sandstone, according to
White,90 is very massive and makes long lines of yellow cliffs sinking
in a southerly direction until they come down almost to sea-level
behind Torres. The deep bore-hole No. 3, situated 20 km. inland
from that place, proved, according to Doctor Lofgren, 122 meters of
Botucatu overlying 145 meters of Rio do Rasto at least, but, curi¬
ously to the southwest, neither at Taquara nor at Santa Maria, is
the upper member represented, though it is reported that a pale
sandstone underlies the lavas in the ragged escarpment between
these two towns.

Traced from Rivera to Tacuarembo, the top of the Rio do Rasto
immediately underlying the basalts develops a harder facies, paler
in exposures, and thus resembles the Botucatu superficially, but is
actually red when fractured, and moreover shows the same degree of
false-bedding as in the Rio do Rasto below. This feature can be
.ascribed mainly to the indurating action of the basalts, for the top is
often brecciated. This material commonly makes scarps and some¬
times caps isolated hills, as in the symmetrical Tres Cerros east of
Tacuarembo or in the similarly styled elevations to the north of
Uruguay ana in Argentina mentioned by Hausen.91

Whether the Botucatu is merely a slightly different facies of the
uppermost part of the Rio do Rasto, or whether it is really a separate
formation only partially developed or missing in certain portions of
the basin, thus allowing the basalts to repose directly upon the lower
division, is not quite clear, and only detailed mapping could settle
this point, which is of no great importance, fortunately.

There can hardly be any doubt, however, as to the predomi¬
nantly eolian origin of the Sao Bento sediments, which is all the more
compelling when comparison is made with the obviously equivalent
Cave and Forest sandstone (Stormberg) of the Cape and Southern
Rhodesia, with their underlying red beds. The first named is similar
lithologically to the Botucatu, displaying features indicative of a
loess-like origin, while the second, as shown by “millet-seed” grains
and strong false-bedding, is of eolian origin, the sediments in both
cases being followed by effusion of basalts in which certain inter¬
bedded sandstones occur.

90 White (1908), pp. 2 1 1-2 1 7.

91 Hausen (1919), PI. VI.

GONDWANA SYSTEM IN BRAZIL, URUGUAY, AND PARAGUAY

(a) Fossils — Under such circumstances the life of the period
would have been scanty and the poverty of fossils would thus find
an explanation. Silicified wood is abundant at many points in the
Rio do Rasto, both low down as well as at the top, for example at
Rivera; such is probably mainly referable to Dadoxylon.

Of Filicales we have only the record of Cladophlebis , determined
by Kurtz92 as C. denticulcita Brongt. from the base of the Tres Cerros
near Tacuarembo, but which after an examination I feel sure is a
distinct and probably new species, though closely related to the
foregoing, which is a Rhaetic-Liassic form.

From a point a little to the south of Santa Maria da Bocca do
Monte the remains were obtained of Scaphonyx fischeri S. Woodw.,93
a dinosaur allied to Euskelesaurus from the upper Triassic Red beds of
South Africa, below which latter horizon dinosaurs have not yet been
discovered. Leme94 mentions the finding of a dinosaur allied to
Scaphonyx at Cambembe, 50 km. to the north of the Chapada in
Matto Grosso, while Von Ihering has recorded a dinosaur tooth in
the sandstone of Sao Jose do Rio Preto, 450 km. to the northwest of
Sao Paulo. Baker has noted the presence of bones near the coast to
the northeast of Torres.

A layer in the core from the bore-hole at Ferreira in Rio Grande
do Sul, cutting the lower part of the Rio do Rasto, yielded me valves
of a small Estheria almost circular in outline and certainly distinct
from the Cyzicus ( Estheria ) draperi so common in Argentina.

It is important to note that as yet no forms ascribable to the
Permian have been found in the sediments of the Sao Bento series
which must be considered as of Trias-Rhxtic age.

(13) The Serra Geral Eruptives or Traps and the Associated Sediments

Crowning the Botucatu, or the Rio do Rasto, where the former
can not definitely be differentiated therefrom, comes a great capping
of lavas, basaltic to andesitic in composition, while in certain locali¬
ties sediment must have been in course of deposition during inter¬
vals of quiescence to show up now as intercalations between the
lavas, though only in the lower part of the volcanic group. Elsewhere,
as in western Parana and Santa Catherina and in parts of Uruguay,
only volcanic material is to be found.

Attention must be drawn to Woodworth’s account95 dealing with
the trap plateaus of Santa Catherina, and particularly to the valu¬
able summary by C. L. Baker entitled ‘ ‘ The Lava Fields of Parana. ” 96
As shown in Baker’s map, the eruptives of the Parana basin form a
complete elongated area, 1,300 km. long, but of rather variable
width, 500 km. across at the broadest, narrowing toward the south-

92 Walther (1919), p. 107, footnote. 94 Leme (1924), p. 189.

93 White (1908), pp. 217-225. 95 Woodworth (1912), pp. 91-99.

96 Baker (1923) ; the scale on the map is incorrectly given.

90 GEOLOGICAL COMPARISON OF SOUTH AMERICA WITH SOUTH AFRICA

west and occupying a tract of fully 800,000 square kilometers in ex¬
tent, including certain stretches concealed beneath the Bauru beds.
Excepting on the west, the lavas generally terminate in erosional es¬
carpments ; they frequently give rise to terraced features and are
responsible for the multitude of rapids and cataracts on the rivers, out¬
standing among which are the magnificent falls of the Iguassu97 with
a height of 60 meters and those of La Guayra on the upper Parana.

While the contact between the volcanics and the sediments
beneath is as a rule a perfectly even surface, attention must be drawn
to certain irregularities first studied in the town of Taquara, north
of Porto Alegre in Brazil, and seen again close to the railway near
Paso del Cerro and in the Cuchilla de Tambores io km. south of
Tacuarembo in Uruguay. These disclosed the fact that the basalts
in these three spots were resting upon and filling up shallow hollows
in an originally uneven surface of sandstone, which depressions in
every case trended a little south of west, a feature worthy of record,
since in South Africa several cases are known of a similar kind along
the Basalt-Cave sandstone contact; these apparently represent
primitive drainage lines over the sandy surface in existence at the
commencement of the period of volcanicity. The section shown in
Figure 6 may therefore be not an uncommon one.

Flows earlier than those usually seen were found deep down in
the Botucatu sandstone at Ityrapina in Sao Paulo, where the deep
boring gave the following downward section, starting at the base of
the main traps: sandstone, 85 meters; basaltic flow, 15 meters; sand¬
stone, 77 meters; basaltic flow, 3 meters; sandstone becoming redder,
more clayey, and calcareous, and hence transitional to the Pyramboia,
48 meters. In South Africa such a similar case has been recorded
from the Maclear district of the Cape Province, where local eruptions
antedated the dominant period of volcanicity.

Thin sandstone intercalations are recorded by Baker generally, by
Walther in Uruguay, and by Sobral and Hausen in Misiones, and are
almost always medium to fine grained — sometimes finer and coarser
banded — red, red-brown, terra-cotta, or even purplish colored,
poorly or cross bedded sandstones or not unusually intensely hard,
glassy quartzites breaking with a conchoidal fracture and so making
very stony outcrops. While probably much of this induration was
effected by heat from the overlying lava, the depth through which
such hardening extends rather suggests the action of hot solutions
carrying silica. On the other hand, it should not be overlooked that
they might possibly have acquired some of this exceptional character
through original silicification prior to the outpouring of the succeed¬
ing lava-flow, for it is well known that under an arid climate sands
may be converted into “surface quartzites” or “silcretes” under

87 See Hausen (1919), PI. IV.

GONDWANA SYSTEM IN BRAZIL, URUGUAY, AND PARAGUAY

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purely natural conditions, as in the Kala¬
hari in South Africa, and that the Botu-
catu was apparently accumulated under
such desert conditions. This is suggestive
because of the very similar silicified char¬
acter beneath the basalts of the Triassic
Forest sandstone of Rhodesia, also a for¬
mation of eolian and presumably of desert
origin. A noteworthy type of rock exten¬
sively used as ballast on the railways at
Santa Maria is a coarse gray grit, which
from inquiry I afterward found came from
B arras, on the railway close to Passo
Fundo, apparently from an intercalation
relatively high up in the volcanics, though
of this I can not be sure. It is remarkable
in that the samples picked up contained
tiny “dreikanter. ” Conglomerates have
been reported to occur in the Botucatu,
and these are manifestly worthy of de¬
tailed study in view of the information
they might yield regarding the geographi¬
cal and climatic conditions in Brazil at
the close of the Triassic epoch.

Above Taquara, on the road to Morro
Fortaleza, not far above the base of the
lava group, there crops out an agglomer¬
ate bed (Fig. 6, j), with a fine, pinkish,
sandy matrix in which was set an abund¬
ance of subangular to rounded fragments
of different kinds of lavas, which bed
passes upward into red cross-bedded
friable sandstone exactly similar to those
of the Rfo do Rasto seen in the town below,
and ending in a sharply defined ‘ ‘ baked
junction against the flow overlying; the
band totals 8 meters in thickness. Ten
meters higher up occur thin sandstone
veins running vertically down into cracks
in the underlying basalt from a higher
thin intercalation of red sandstone ; clearly,
just as in South Africa, eolian conditions
seem to have lingered on while the earliest
lavas were being erupted.

92 GEOLOGICAL COMPARISON OF SOUTH AMERICA WITH SOUTH AFRICA

Some of the thin intercalated sandstones and quartzites in the
basin are reported to contain fragmental igneous matter, and indeed,
in the Territory of Misiones in northeastern Argentina, such layers
may be tufaceous in their character.97 Such bands have been passed
through in certain of the borings, for example in those at Posadas,
Solari, and Mercedes (Corrientes). It is worthy of note that tufa¬
ceous layers should also have been found at a lower horizon (in the
Rio do Rasto) in the bore-hole at San Cristobal (Santa Fe) still
farther to the west, where the volcanics were struck beneath the
Neogene at 73 5 meters, the Triassic sediments being cut at 900 meters,
underlain by possibly Bonito beds from about 1,141 to 1,384 meters.
A rather similar succession was intersected between 860 and 1600
meters in the boring at Tostado, a little to the northeast, which helps
to link up the strata of the Parana basin with the Paganzo of the
Cordoba and La Rioja districts. In Laguna Paiva No. 2, a little to
the north of Santa Fe, the amygdaloids were struck at 602 meters
and not bottomed at 638 meters.

(14) The Volcanics

As various observers have pointed out, many of the flows are
relatively coarse-grained, compact rocks difficult to distinguish from
intrusive sheets, but as a rule such types, when satisfactorily exposed,
display vesicular structure at the top, if not at the very base. Though
not recorded by previous workers, I found “pipe amygdaloids”
developed at the bottom of the flows in several places and at Taquara
also “vesicle cylinders” and “bubble trains” set vertically in non-
vesicular basalt, just as can be instanced from the Stormberg series.98

Some of the lavas are highly vesicular and even cavernous, Brazil
and Uruguay being noted for the large quartz-filled geodes and hydro-
lytes that have become weathered out in the red loamy soil; others
are very dense, in which case there is sometimes a columnar structure.
In color they range from black to dark green, purple, brown, red, or
chocolate. Native copper is occasionally to be found in them. The
thickness of the individual flows varies from 0.5 meter upward, the
general value being probably anything up to 50 meters or thereabouts,
though Woodworth has spoken of sheets from 95 up to perhaps 190
meters thick in the eastern part of Rio Grande do Sul. There are no
references to the occurrence of thin layers of red bole or earth between
successive effusions, and in this respect the volcanics are like those
of South Africa, for which the evidence points to the rapid welling out
of flow after flow without any lengthy time interval, probably under
a dry climate such as would have hindered the rapid weathering of
the lava crusts.

As regards the thickness of the group, Baker99 states that in
different parts of the basin figures of from 250 to 500 meters have
97 Hausen (1919). 98 Du Toit (1907). 99 Baker (1923), p. 72.

GONDWANA SYSTEM IN BRAZIL, URUGUAY, AND PARAGUAY 93

been measured, although much rock must have been removed by
erosion from over this great region. In one of the borings at Curuzu
Cuatia, on the lower Parana River, between Corrientes and Concor¬
dia, the base of the volcanics (from which intercalated sediments
were absent) was not passed through at 486 meters even. In this
respect, therefore, the group is comparable with the Stormberg
basalts, wherein a thickness of over 1,000 meters has been recorded
in Basutoland and 400 meters in the Kaokoveld.

(15) Petrology

The bulk of the flows are “melaphyres” in which olivine is
absent or else in small individuals, usually much altered to serpentine,
or, as in Uruguay according to Walther, to iddingsite, while the
structure is in general ophitic to subophitic, features that exactly
duplicate those of the Stormberg volcanics. Hausen observed no
porphyritic structures in Misiones, but Walther mentions types
approaching the porphyrites in Uruguay, while Baker refers to
augite-porphyrite and Branner records the presence of such types in
Rio Grande do Sul and Hussak in Santa Catherina and Sao Paulo.
This is instructive because, although porphyritic basalts are unrep¬
resented in the Union of South Africa, they appear occasionally up
the Zambezi-Linyanti Valley and are well marked in the Kaokoveld
of Southwest Africa. Andesitic varieties are sometimes present in
Brazil, as at Santa Maria.

Doubtless the lavas issued mainly from fissures, now occupied
by narrow vertical dikes of basaltic or doleritic rock, but at Santa
Maria what was taken to be a volcanic neck was observed in the face
of the spur north of the town, facing Pedreira and overlooking the
railway to Passo Fundo. It cuts the hard interbedded sandstone
capping the ridge and is filled with a pale scoriaceous rock, banded in
nearly vertical fashion parallel to the wall of the pipe.

Regarding the age of the Serra Geral eruptives, it can hardly be
doubted that, like those in western Argentina and Patagonia, they
are Rhaeto-Liassic, though direct evidence thereon is wanting.

(16) The Intrusive Dolerites or Diabases

Penetrating the strata of the Santa Catherina system, but more
commonly its lower half, are these well-known extensive sheets and
dikes of basic rock that are manifestly closely allied to the Serra
Geral eruptives, though, so far as can be gathered, of slightly more
basic composition. Numerous references will be found in the geolog¬
ical literature to such sills, but no comprehensive account thereof.
Baker has indicated on his small-scale map the areas outside the
basin proper where they have been observed by him, and he notes
that they also penetrate the basement formations in Paraguay and
the southern part of Matto Grosso.

They are common in the Itarare, Bonito, and Iraty beds, but the

94 GEOLOGICAL COMPARISON OF SOUTH AMERICA WITH SOUTH AFRICA

impression that I obtained from journeys between Porto Alegre
through Santa Maria and Rivera to Montevideo, where excellent
sections are furnished by numerous railway cuttings, was that such
intrusions were distinctly scarce in the upper part of the system and
then generally dike-like, just as is the case in the Karroo. Further,
it may be affirmed that the relative proportion of igneous rock is
much less than in the dolerite-riddled portion of the Union of
South Africa. Their precise relationship to the eruptives has not yet
been worked out, but arguing from analogy from South Africa1, they
would most probably have been injected into the framework of South
America during or probably just after the eruptive phase, and hence
probably date from the beginning of the Jurassic.

They display no unusual petrological characters, ranging from
dolerites without olivine to olivine-dolerites, and having subophitic
or ophitic structures. A typical sample from a bore-hole near Rio
Claro in Parana possessed a specific gravity of 3.02. '

SECTION L. THE NORTHEASTERN REGION OF BRAZIL

Mainly to Lisboa,2 Crandall,3 and Small4 is due our knowledge of
the quite considerable area of Permo-Triassic in Maranhao, Piauhy,
and the northeastern part of Goyaz. Quite unjustified is its southerly
extension, as shown on Branner’s geological map of Brazil, so as to
join up with the strata of the Parana basin, the formations filling the
broad gap being either pre-Carboniferous or post-Triassic, though
probably the latter may conceal some Gondwana beds.

The strata are lying nearly flat, resting on crystallines, but in the
east, according to Small, unconformably on the thick Serra Grande
series, described elsewhere (possibly of early Palaeozoic age), and are
overlapped to the north by the Cretaceous and the coastal Tertiaries.

The lowest beds, of Permian age, make a broad, sweeping horse¬
shoe, extending from the north of the Pamahyba River southward
through Piauhy, then westward to the Rio Tocantins and down the
latter to the borders of Para. The higher horizons lie within the
curve, the Triassic appearing toward the north and covering a
limited area about the headwaters of the Mearim River in Maranhao.

Called by Lisboa the ‘ ‘ Pamahyba series ” and divided by him into
several groups totaling a few hundred meters in thickness, so far as
one can gather, the beds consist successively of gray calcareous shales
and gray to white sandstones, a thick red sandstone having purple
spots and with pisolitic limestone, a gray sandstone followed by green
and chocolate shales, and limestones with cherty bands. Glacial
signs are absent at the base. Psaronius associated with gymno-
spermous wood has been found in many localities in this wide region
throughout the full thickness of strata, together with the cast of a
stem referred to Sigillaria in Piauhy. Since the first-named occurs,

1 Du Toit (1920). 2 Lisboa (1914). 3 Crandall (1910). 4 Small (1914).

GONDWANA SYSTEM IN BRAZIL, URUGUAY, AND PARAGUAY 95

according to Derby, in Sao Paulo State associated with Stereosternum
and Lycopodiopsis, such would suggest that the Parnahyba series
probably represents horizons from about the Iraty upward and hence
mainly of Permian age, the beds being all of fresh-water origin,
apparently.

The succeeding “Mearim series” consists of a few hundred
meters of white, splotched, and red sandstones overlain by flow’s of
basic amygdaloidal lavas, which are also intercalated in the red
sandstones, the strata building table-topped hills, well represented
between Grajahu and Pastos Bons, while they and the underlying
beds are, furthermore, cut by intrusive dolerite in the form of sheets
and dikes.

There can be no doubt that this upper series, older than the
Cretaceous and so like the Sao Bento of southern Brazil, is of Triassic
age, support for which is found in the discovery of scales of Semio -
notus near Floriano on the Parnahyba River.

Attention might furthermore be directed to the general parallel¬
ism in facies with the ‘ ‘ Karroo ” succession of the Low'er as contrasted
with the Upper Congo basin in Africa, namely, in the absence of
glacials, the shaly and often slightly calcareous character of the
Lualaba beds with fish and crustacean remains, and the succeeding
yellow or pink friable Lubilache beds, though volcanic rocks are not
known to overlie the latter.

SECTION M. EASTERN BRAZIL

In the coastal region of Bahia and Sergipe, Branner 5 has described
under the name of the “Estancia beds” certain strata, which he
placed in the Permian, that occupy the region from Bahia nortlrward
to the Rio Sao Francisco, though much concealed by Cretaceous and
Tertiary formations. Subsequently Soper 6 has removed a part of this
to the Cretaceous and has furthermore stated that the Estancia beds
pass down, apparently wdthout a break, into a thick series of rocks
that rest unconformably upon an uneven surface of crystallines and
proterozoic (?) quartzites. It totals no less than 3,700 meters, the
beds being tilted and sometimes considerably disturbed, and even
faulted, the foldings trending generally a little east of north, but
along other axes as w^ell, overlain discordantly by gently inclined
Cretaceous and by horizontal Tertiaries.

In the lowrer part are seen shales, slates, and gray to pink lime¬
stones, followed by a great mass of green, blue, dark or dark red, often
micaceous, shales, succeeded by red sandstones and by blue lime¬
stones. The finding of Alethopteris branneri White in a dark shale
beneath red Cretaceous sandstone at Aracy, and according to Leme 7
of Psaronius near to Conselho, would suggest an upper Carbonifer¬
ous or more likely a lowrer Permian age for the upper part of the series;

6Branner (1913). 6Soper (1914), pp. 25-37. 7Leme (1924), p. 181.

96 GEOLOGICAL COMPARISON OF SOUTH AMERICA WITH SOUTH AFRICA

consequently the basal portion may extend well back into the
Carboniferous.

Comparisons may be instituted with the gently tilted formations
in the western part of the Belgian Congo, particularly the middle
portion of the Kundulungu, called by Cornet the “Mpioka series, ”
with its red coloration.

It is just possible that the horizontal limestones and shales of the
Salitre Valley in Bahia, extending over wide areas to the southwest
thereof, resting unconformably upon much older formations, and
tentatively placed by Branner8 in the Permian, may belong to the
Estancia series, but palaeontological data are essential before any
further advances can be made. In the coastal zone to the south of
Bahia near Cannavieiras beds occur on the Rio Pardo and Rio
Jequitinhonha that have yielded plants referred by Hartt to Aster o-
phyllites (?) scutigera, suggested by D. White as perhaps a Phyllo-
theca.9

Nevertheless, the following important points have been estab¬
lished: (i) The presence of some undoubted late Palaeozoic continen¬
tal beds in the coastal region; (2) their partially calcareous nature;
and (3) their disturbance by early mesozoic movements not alto¬
gether coinciding in trend with the ancient “Brasilides, ” the signifi¬
cance of which will be remarked on in Chapter VI.

SECTION N. THE CRETACEOUS OF THE INTERIOR

Brief reference only will be made to the continental Bauru beds
of Sao Paulo State that rest horizontally and unconformably on the
Triassic traps and are probably of Cretaceous age. Their precise
distribution being not very well known, these beds are not indicated
on the accompanying geological map, but it might be remarked that
they occupy wide areas, forming much of the higher ground border¬
ing the Parnahyba, Rio Grande, Tiete, and Paranapanema, and
extend down the valley of the Parana to Guayra, while beyond at
San Ignacio near Posadas the sandstones have been brought down to
river-level by warping. The transgressive base is indicated by the
fact that they rest on the traps between Bauru and Agudos, but on
the Triassic sandstone at Botucatu. They are composed chiefly of
massive and often false-bedded white to red sandstones with a cal-
careo-argillaceous cement. Farther north they form a broad covering
along and west of the Rio Sao Francisco, known here as the “Pira-
pora sandstone, ” and appear to connect up with the slightly younger
but marine Cretaceous of rather similar character of Piauhy and
Ceara. These beds rest very largely upon a peneplain cut across the
underlying formations of Brazil, and thus reveal the very consider¬
able denudation of the continent during the Jurassic epoch.

8Branner (1913), p. 626; (1919) p. 237; Crandall (1919), p. 244. 9 White (1908), p. 423.

CHAPTER VI

GEOLOGICAL HISTORY OF THE AFRO-AMERICAN

LAND MASS

That these two continents were intimately connected during
several geological epochs will, I venture, be acknowledged after the
perusal of the preceding pages, though the manner of such union
would admittedly be speculative. In preparing this review an
attempt was made first of all to write the historical account, irrespec¬
tive of any hypothesis as to the manner of such union or of the
ultimate mode of separation of the land-masses though it became evi¬
dent, as the data were assembled, that they pointed very definitely in
the direction of the displacement hypothesis, and that they could
most satisfactorily be interpreted in the light of that brilliant
conception.

It was finally decided to treat the subject from this viewpoint
rather than from any other, but only in such a way as to bring out
particular features the significance of which would otherwise be
overlooked; the hypothesis itself could then be discussed indepen¬
dently and without prejudicing this particular chapter.

THE SILURO-DEVONIAN

Knowledge concerning the early limits of the Afro-American
mass only becomes definite during the late Silurian, when the ocean
must have covered the central Sahara, western Africa, the lower
portion of the Amazon Valley, parts of Bolivia, Jachal, San Juan, and
Mendoza, but not the Nevado de Famatina. The faunas up to
the very close of that epoch were, it is essential to note, boreal in
their aspect.

Attention has more especially to be focussed on far distant
Bolivia, because of the light which its splendidly developed lower
Palaeozoics shed on the precise age of the unfossiliferous sandstone
formations of Parana and the Cape, customarily ascribed to the
lower Devonian. The valuable accounts of the stratigraphy of this
country by d’Orbigny,10 Steinmann,11 Ulrich,12 Knod,13 and others,
supplemented recently by Kozlowski14 and Bonarelli,15 clear up
many points, although showing the need for further investigation.

Following Knod and Kozlowski, the normal Bolivian succession,
resting usually on the Ordovician, is divisible into: (i) The lower or
Ida sandstone, about 170 meters thick, with unfossiliferous lower

10D’Orbigny (1842). 12 Ulrich (1893). 14 Kozlowski (1923).

11 Steinmann (1904). 13 Knod (1908). 15 Bonarelli (1921), pp. 39-56.

98 GEOLOGICAL COMPARISON OF SOUTH AMERICA WITH SOUTH AFRICA

half (a greenish gray or whitish quartzose sandstone overlain by
gray calcareous sandstone and calcareous flagstone; (2) the Conu-
laria and Crinoid beds some 200 meters thick (dark shales and sandy
shales with calcareous nodules, like those of Parana) ; (3) the upper
or Huamampampa sandstone up to 250 meters thick (grayish and
unfossiliferous) . These 700 to 800 meters of beds are generally
agreed upon as representing the lower Devonian alone (Oriskany),
but Kozlowski has stated that around Lake Titicaca there is
(4) the Sicasica formation (quartzites of a warm color, micaceous
brown or white shales with sandy layers and black siliceous nodules) ,
with a fauna showing middle Devonian forms together with a few
lower Devonian types followed by unfossiliferous sandstones and
shales — Onondaga-Hamilt on .

Now, both in Parana and the Cape the sequence is almost identi¬
cal, the barren Furnas and Table Mountain sandstones being respec¬
tively followed by the dark fossiliferous Pont a Grossa and Bokkeveld
shales, which are unquestionably equivalent to the Conularia and
Crinoid shales of Bolivia, as borne out by their particular faunas.

On the other hand, Kozlowski16 and Bonarelli17 have independ¬
ently pointed out that in parts of Bolivia this important system
actually includes in its basal section strata that belong to the upper¬
most Silurian, and which, although of no great thickness, are wide¬
spread to the north and southeast of Sucre, being characterized by
the presence of Clarkeia antisiensis ( Liorhynchus bodenbenderi ) and
several other forms not found associated with the typical Devonian
faunas. At Tarabuco, east-southeast of Sucre, the succession resting
upon the Ordovician consists of 40 meters of barren white quartzite,
30 meters of yellow to red sandstones with Clarkeia , overlain by some
hundreds of meters of yellowish sandy shales, in the upper part of
which fossils characteristic of the Icla shales occur; at Finca Con¬
st ancia to the north of Sucre a rather similar order can be seen. That
is to say, where the normally unfossiliferous basal group of whitish
quartzitic sandstones has developed a marine facies, the latter now
carries not Devonian but Silurian forms, wherefore the presumption
is strong that the basal part of the equivalent Furnas and Table
Mountain sandstone is in each case of uppermost Silurian age. It is
significant that the only molluscan remains yet found in the Cape
formation — unfortunately not identifiable — should occur at the
very base of the sandstone.

A parallel is forthcoming from Jachal, where Keidel,18 studying
the unbroken succession in the Lomas de los Piojos, has recorded the
zone with Clarkeia antisiensis and Monograptus priodon, composed of

“Kozlowski (1923), pp. 8-10.

“Bonarelli (1921), pp. 46-53.

18 Keidel (1921), pp. 32-37, 51-54; Clarke (1913), P- 332.

GEOLOGICAL HISTORY OF THE AFRO-AMERICAN LAND MASS 99

green and dark micaceous shales, which are followed by 800 meters of
“Devonian,” the basal 500 meters being unfossiliferous sandy
shales, greenish and bluish gray sandstones with dark sandstone ribs,
followed by similar gray and green beds, but with the typical forms
of the “austral” Devonian of Bolivia, Parana, Falklands, and Cape.

THE DEVONIAN OSCILLATIONS

These illuminating sections in Bolivia prove, therefore, that the
great “Devonian” transgression really began just prior to the close
of the Silurian. At that period Central Africa had been land probably
as far northward almost as Nigeria and southward right to the Cape,
while most of eastern and southern Brazil, Uruguay, southeastern
Bolivia, and northern, central, and eastern Argentina were bound
to that continent.

Along the margins of this land-mass were then accumulated the
siliceous deltaic deposits of Parana, Matto Grosso, Sierra de la
Ventana, the Falklands, and the Cape (from Clan william in the
west to Zululand in the east), while, as the ocean advanced and the
area of this section of Gondwanaland decreased, the delta fringe
crept inward and marine muds and sands with a lower Devonian
fauna of austral type came to be laid down on them. In Africa, the
Gold Coast region was ultimately submerged, and in the opposite
direction the southern third of the Cape and the whole of the Falk¬
land Islands; whether the Cordoba-San Luiz region remained as
an island is unknown, but certainly Jachal and Salta were inundated,
though probably not the Famatina, Puna de Atacama, or the center
of La Rioja.

A cool climate is expressly indicated by the glacial zone of the
Table Mountain series, and indirectly by the dark gray, blue, and
green coloring of the marine strata, by the absence of limestones, and
scarcity of corals in them; everywhere a shallow ocean has to be
postulated, which would explain the widespread transgression of its
waters in certain territories.

THE DEVONIAN FAUNAS

With the lower Devonian, for reasons not yet understood, came
strong faunal differentiations. The boreal element still predominates
in the Sahara,19 as shown by species from Rhineland and North
America, but an austral bias is signaled by such forms as Homolo-
notus herscheli , Leptocoelia flabellites, Spirifer rousseauxi , etc. The
Maecuru (Amazon) assemblage, while showing alliances with the
European, displays the North American — Oriskany-Onondaga —
facies, but the austral element is nevertheless quite marked in certain

19Haug (1905); Lemoine (1913), p. 19.

100 GEOLOGICAL COMPARISON OF SOUTH AMERICA WITH SOUTH AFRICA

groups, particularly among the trilobites, with peculiarities among
the brachiopods, e.g., the Spirifers, which are more marked still in
the Bolivian and west Argentine areas. The fauna of Matto Grosso
is not far removed from that of Bolivia, but the west Argentine one
again stands apparently closer to that of the Falklands than to
Parana. Clarke 20 has commented on the fact that the Falkland fauna
is much closer allied to the Bokkeveld of the Cape than to the South
American assemblages, peculiar only so long as one disregards the
doctrines of the displacement hypothesis, for under the latter these
islands would have been nearer geographically to South Africa than
to Brazil. We know that some high ground must have lain in early
Devonian times to the west and northwest of the Cape (sufficient to
support local glaciers) , while the sources of the siliceous formations of
Sierra de la Ventana and Parana probably lay to the east rather than
the west. Consequently the Parana region might well have occupied
an embayment with a promontory intervening between the Brazilian
and Falkland shore-lines.

Our knowledge concerning much of the periphery of Gondwana-
land ceases with the lower Devonian, but during the mid-Devonian
the ocean persisted in the Amazon region and in northern Bolivia.
The Brazilian Erere fauna shows increased affinities with the North
American, in addition to forms from the Maecuru, but it also has
alliances with the Sicasica fauna of Bolivia through such forms as
Tropidoleptus carinatus and Homolonotus dekayi , typically Hamilton
species, the latter represented also in Gold Coast Colony.21 In Ahnet
(Sahara) the mid-Devonian carries Agoniatites vanuxemi , characteris¬
tic of the Marcellus stage of New York, while the upper Devonian of
Tassili shows affinities with North America. Faunas of late Devonian
age are not yet known in South America outside of the Amazon
Valley.

y THE CARBONIFEROUS EPOCH

The oscillating shallow seas then withdrew — probably the conti¬
nent rose isostatically — for in South Africa, the Falklands, and the
Sierra de la Ventana area siliceous estuarine and fluviatile beds of
presumably upper Devonian-lower Carboniferous age (derived in
the first-named from the erosion of the old Devonian land-mass)
succeed the marines with but a few plant remains. At Paracas on
the coast of Peru are the only other known plant-bearing strata,
probably of middle Carboniferous age.

Only in southern Peru, a little north of Lake Titicaca,22 are marine
beds represented in South America, of undoubted lower Carbonifer¬
ous (Avonian) age, though present in Gold Coast Colony and the
Sahara, and it would appear that the ocean then retreated to beyond

20 Clarke (1913), pp. 13, 56. 21Kitson (1925). 22 Douglas (1920).

GEOLOGICAL HISTORY OF THE AFRO-AMERICAN LAND MASS 101

its limits during the Silurian, thus presenting an increased area of
land to erosion. A certain amount of folding occurred in the pre-
Andine regions about this time, seemingly with the injection of
granites in Peru and Bolivia.

With the upper Carboniferous came a return of the ocean, which
entered the lower Amazon region and occupied a large part of Peru
and Bolivia, but the block between the Puna de Atacama and Potosi
remained land, around which a gulf of the sea must have crept to
penetrate into the western part of San Juan and parts of Chile on
about the same parallel of latitude ; all the country to the northeast,
east, and southeast of San Juan probably remained unsubmerged.

The upper Carboniferous occurs on either side of the Amazon
River with wide extension — a group of limestones, shales, and sand¬
stones, perhaps 600 meters thick, with an abundant fauna, including
Productus cor a , P. semireticulatus, Athyris subtilita, Spirifer earner a-
tus , etc., allied to the upper Carboniferous of the United States and
Urals and showing resemblances to the Carboniferous of Bolivia and
Peru on the one hand and of the Sahara on the other. Most curiously,
as Doctor Reed has well pointed out, the equivalent fauna from
Barreal is quite distinct from those recorded elsewhere in North or
South America, the forms being nearly all either closely allied to or
comparable with established species from the lower Carboniferous of
Europe or the middle or upper Carboniferous of Russia or parts of
Asia. Probably, therefore, the western part of San Juan was not in
direct communication with the ocean to the north. The fauna, it
might be noted, displays no affinities with those of eastern or west¬
ern Australia.

THE CARBONIFEROUS GLACIATION

Time is revealing more and more the number of places where the
/ Carboniferous glaciers passed into a shallow ocean and, melting,
I dropped their burden, for example in Tasmania, New South Wales,
Western Australia, the Salt Range in India, the San Juan district in
Argentina, and Parana in Brazil. It has furthermore become evi¬
dent that over wide areas the ice must have traveled across a gently
undulating surface nearly at, if not below, sea-level, as is proved by the
shales with marine mollusca in Parana and Southwest Africa, by the
Dwyka shales of South Africa, Bonito coal measures of Brazil, etc.
The general low relief of the ice-ridden territory is indeed one of the
most unexpected peculiarities of this Palaeozoic glaciation.

I have adduced evidence to show that in South Africa23 the glaci¬
ation apparently started at several centers, in each case over some¬
what higher ground, but that the ice-sheets at the maximum stage of
glaciation seem to have coalesced, to discharge southward into a

23 Du Toit (1921).

102 GEOLOGICAL COMPARISON OF SOUTH AMERICA WITH SOUTH AFRICA

body of probably fresh water. An important center was situated in
Southwest Africa, but it is not at all unlikely that a similar feature
lay to the northwest or even west of the Cape (from which direction
had indeed come the local glaciers of the Devonian) , suggestive being
the “boulder pavement” at Eland’s Vlei on the Doom River, with
its groovings directed nearly west-east.

In South America the evidence consistently favors an ice center
situated out in the present Atlantic, the significance of which will be
appreciated from the study of Figure 7. The position allotted to the
Falkland Islands in this geographical scheme is determined approxi¬
mately by a series of rather pretty comparisons: (1) The folding is
along two axes, one directed west-northwest and the other at right
angles thereto, but of fairly open character as a rule, with dips else¬
where generally low over wide areas, and thus comparable with the
Ceres-Clanwillian region, and neither with the Caledon-Riversdale
sections nor with Argentina, where the first-mentioned set of foldings
is dominant and intense; (2) the lower Devonian sandstones are
gritty and pebbly, as in the Cape-Clanwilliam region or in Parana,
and not quartzitic, as in Mossel Bay or in the Sierra de la Ventana,
moreover, the glacial horizon of the western Cape may, according to
Baker, just possibly be represented in West Island; (3) the fauna of
the Devonian shales in the Falklands is very closely related to that
of the Bokkeveld, less so to that of Parana ; (4) the Devono-Carbonif-
erous quartzites of the Falklands are identical with the Witteberg
series of the Cape and not closely comparable with the greywacke
phase of the Sierra de la Ventana; (5) the strongly cleaved tillite of
the islands is slightly disconformable to these quartzites, as in Clan-
william, whereas the glacials of the Rio Sauce Grande are conform¬
able to the strata below, just as in the south of the Cape (Worcester) ;

(6) the tillite is of great thickness, with some intercalated shales, and
hence like that of the southern Karroo and the Rio Sauce Grande;

(7) the Lafonian sandstone, just above the tillite, has no lithological
representative in the Cape, but finds its equivalent in the Itarare
series of Uruguay and Brazil; (8) the absence of the “ Mesosaurus
zone” links the islands with Argentina; (9) the great development
of Lafonian sediments devoid of coals recalls the facies of the Sierra
de Pillahuinco and the Karroo of the southern Cape rather than that
of the northern Karroo or of Parana; (10) the upper Lafonian beds
show lithological resemblances with the upper Karroo and not the
Triassic of South America; (11) the few dolerite intrusions suggest
again the Cape-Clanwilliam region.

If we admit the displacement hypothesis, these affinities would
collectively assign the Falklands to a position along the northern
edge of the broad belt of foldings that linked the Cape with Argen¬
tina, but would place them somewhat nearer to Africa. Despite the

GEOLOGICAL HISTORY OF THE AFRO-AMERICAN LAND MASS 103

fact that these islands rise from the Patagonian coastal shelf, and
that the late Mesozoic foldings (Patagonides) strike southeastward
near the Gulf of San Jorge, and therefore toward them, as remarked
by Windhausen,24 the Falklands, if we ignore the mere tectonic
parallelism, display not the slightest affinities with Patagonia, where
the late Triassic volcanics and sediments rest upon the crystallines,
with no representatives of the Palaeozoics. It must accordingly be
concluded that this outpost of Gondwanaland belongs to the north¬
east rather than to the west and actually affords very striking sup¬
port to the displacement hypothesis. The record by Schwarz of
granite, probably from volcanic ejectamenta, in Tristan da Cunha is
an indication of crystalline plutonics underlying part of the South
Atlantic basin.

The north-south directed groovings beneath the tillite in the
Falklands would lend a modicum of support to such an hypothetical
ice-center situated out in the Atlantic, though impinging on Brazil,
as indicated by the common absence of the glacials in the southern
corner of that country, by the fluvio-glacials in Santa Catherina,
Uruguay, and San Juan, and the marine glacials in Parana and near
Barreal in San Juan. The conditions in Goyaz and Matto Grosso are
not yet known, while it is uncertain that ice formed at this date in
Bolivia, since the glacials of the Bermejo series may perhaps be of
Permian age.

In 1 92 1 ,25 1 ventured to point out that the evidence in South Africa
favored the deduction that the several centers had become glaciated
in turn, the earliest on the west, the latest on the east. Both in New
South Wales (Seaham area) and in San Juan Rhacopteris and Car diop¬
ter is are present between the lowermost glacials, while such is not the
case in Brazil, South Africa, India, Victoria, or Tasmania. Although
the palaeontological evidence on all these points is not as definite as
could be desired, it would appear that glaciation commenced in the
middle or early upper Carboniferous in the Southern Hemisphere in
the Seaham area, extended to Argentina, then to South Africa, to the
west of Australia, Tasmania, and India during the upper Carbonifer¬
ous, and recurred during the early Permian in New South Wales
and perhaps still later in Bolivia and the eastern Congo.

Under the displacement hypothesis, not only would all the areas
affected be brought together in the most simple manner, within an
oval perhaps no larger than the African continent, but the non¬
synchronism of glaciation in the several parts would find their
explanation as the natural outcome of an extensive active ice-cap,
the margins of which progressively advanced in one direction and
retreated in the other, so that with time the sheet had as a whole
migrated over the surface, glaciating various sections in turn, exactly

24 Windhausen (1921a), p. 6. 26 Du Toit (1921).

104 GEOLOGICAL COMPARISON OF SOUTH AMERICA WITH SOUTH AFRICA

as seems to have been the case with the Pleistocene Ice Age in the
Northern Hemisphere. This view would perhaps meet Coleman’s
well-founded criticism of the excessive size of the single ice-cap under
this supposition.26

The causes of this intense refrigeration, lasting through about
an entire geological epoch, are still largely speculative, but some
additional suggestions may be thrown out. I had tentatively
advanced the hypothesis of “eccentric ice-capping” to explain the
growth and migration of ice centers, but a second aspect, not yet
brought forward, is a possible variation in the crustal heat of the
earth locally, all explanations having hitherto sought for such causes
outside the lithosphere. Admitting the probability of Joly’s theory
of the connection between radioactivity and diastrophism, it would
follow that periods of liquefaction of the subcrust and the abnormally
rapid escape of internal heat by volcanism and hypabyssal injection
would be succeeded by intervals of quiescence, endothermic reac¬
tions, and reduced heat transference. A certain section of the crust
might thereupon come to have over, a period an exceptionally low
geothermic gradient, under which refrigeration would at least be
facilitated, provided that climatic and other well-recognized predis¬
posing agencies were concurrently present. That the entire crust
of the globe should have been simultaneously affected in any such
manner is, however, almost unthinkable.

CARBO-PERMIAN SEDIMENTATION

During the closing stages of glaciation, the upper Carboniferous
ocean, with its characteristic Spirifer and Productus fauna, occupied
the Amazon region, Peru, and Bolivia, and penetrated into the
western part of the San Juan. In some extraordinary fashion, the
remarkable Eurydesma fauna of the Salt Range and Hunter River
area makes its appearance in Southwest Africa, though by what
channel this specialized lamellibranch form reached this spot is
unknown, but presumably via the Cape, for a route across Africa
from Mozambique, while not yet proved impossible, is rather unlikely.

In southern Brazil, Uruguay, Paraguay, and western Argentina
deltaic deposits were laid down, the “ Glossopteris flora” flourished,
and the coals of Brazil were formed; the areas marginal thereto
received estuarine, lacustrine, or “basin” deposits, for example the
Cape, Southwest Africa, and eastern Argentina. A deepening of the
waters then drowned these deltaic or shallow-water deposits, except
in western Argentina, Bolivia, and Africa north and east of the Cape,
in which directions the ground presumably stood higher, and within
this immense area of open water the black, sulphureted, and often
limy muds of the Iraty-upper Dwyka shales were, as suggested by

26Coleman (1926), p. 260.

GEOLOGICAL HISTORY OF THE AFRO-AMERICAN LAND MASS 105

the writer, deposited in an estuary or land-locked sea like the Gulf of
Bothnia.27 The deeper, sulphureted waters were unfavorable to
bathyal life and almost the only forms were fishes, the swimming
Mesosaurus , and Crustacea. The development of bedded limestones
in Sao Paulo indicates communication in that direction with the
northern Permo-Carboniferous ocean — a broad region of marine
deposition in the Triassic after an intervening period of elevation
and erosion.

In Natal, Transvaal, and Rhodesia28 deltaic coal measures were
laid down on an extensive scale, into which crept a few relics of the
northern flora, introduced presumably by way of Brazil, though fail¬
ing to reach Rhodesia or India. In the west and south of the Cape, in
the Falklands, and in eastern Argentina the deposits were of the kind
called “basin” by the writer for want of a better term — a monoto¬
nous succession of fine sands and silts, often ill-differentiated, with
occasional “marls” and calcareous nodules, laid down on interior
plains or in very wide and shallow depressions subject to flooding and
desiccation like those of Turkestan. The conditions were, however,
favorable for vertebrate life, as shown by the wonderful reptilian and
amphibian fauna of the Beaufort beds of southern Africa, the forms
appearing earliest in the southwestern comer of the Karroo and
spreading thereafter to the northeast, through East Africa to Mada¬
gascar, India, and even Russia, accompanied by members of the
Glossopteris flora.

THE PERMO-TRIASS1C MOVEMENTS

Hitherto crustal movements had been mild and generally in the
vertical direction over this section of Gondwanaland, but at the
close of the Permian a lengthy arc of compression (the Gondwanides)
came into being, extending east-west through the south of the Cape,
the Sierra de la Ventana, Sierra Pintada, and northward to the
Puna de Atacama, the strata therein becoming crumpled and in places
overturned to the north and northeast. That these may have been
“coastal” ranges is suggested by the presence of marine Triassic and
Liassic beds at a few localities outside the arc, whereas just inside the
area inclosed by the latter — a ‘ ‘ foreland ’ ’• — only continental deposits
have been found. During the early Triassic these border ranges
were, however, actively eroded, so that in the later part of that epoch
sediments and volcanics were being deposited unconformably upon
the tilted Devono-Permian succession, both in the Cape and Argen¬
tina, to the south of the fold-belt in places upon the pre-Devonian
basement, and to the north and northeast thereof upon only slightly
disturbed Permian, and hence without marked discordance as a rule.

27 Du Toit (1921).

28 The conditions are more fully discussed by Du Toit (1926), Chapter XXI.

106 GEOLOGICAL COMPARISON OF SOUTH AMERICA WITH SOUTH AFRICA

THE ARIDITY OF THE CLOSING TRIASS1C

The climate, which presumably had generally been warm and
dry, appears to have finally become more and more parched, until
toward the close of the Triassic the material being deposited over
wide areas in Brazil, Uruguay, Paraguay, and the southern half of
the African continent consisted of fine-grained, cream, pink, or red
sands, sometimes with well-rounded and polished grains and with .
marked false-bedding, stuff which must largely have been of desert
origin, e.g., the Botucatu and Rio de Rasto in the Parana Basin, the
Forest-Bushveld-Cave sandstone of the Union, Southern and North¬
ern Rhodesia, the Lubilache of the Congo basin, and probably the
Adigrat beds of Abyssinia, covering areas totaling several millions of
square kilometers.

Lithologically these various deposits in no small degree resemble
the Quaternary Pampean loess of Argentina, with its prevalent pink¬
ish, sandy material with calcareous concretions, largely windbome
in its origin and of great thickness in places; in other respects the
Tertiary- Quaternary Kalahari beds of Bechuanaland, with fluviatile
and dune sands overlying in places marls, clays, and some con¬
glomerates. The fact that the conditions in Europe during the
closing part of the Triassic were largely desert would almost suggest
a period of universal desiccation, although animal life could by no
means have been scanty. Fluviatile and lacustrine phases have
yielded the well-known Thinnfeldia flora (together with Estheria ),
significantly on the margins of this gigantic region, i.e., western
Argentina, Chile, Cape Province, peninsular India, Tonkin, New
South Wales, Queensland, and Tasmania.

THE MESOZOIC ERUPTIONS

Outstanding too, is the enormous scale of the basic effusions at
the close of the Triassic, under which vast territories in the two con¬
tinents were flooded with basalts, in places to depths of over 1,000
meters, i.e., the Parana basin, the limited region in Maranhao, the
much-dissected relics in western Argentina, together with extensive
outpourings, mainly of acid character, in Neuquen and Patagonia,
the Stormberg lavas of the Union of South Africa, Lebombo, South¬
ern Rhodesia, lower Zambezi Valley, and Kaokoveld. In practically
every case thin sedimentary intercalations are to be found in the
basal part of the volcanic groups, certain of which indicate the per¬
sistence of arid conditions.

Conspicuous too are the accompanying sills and dikes of dolerite
(diabase) that, avoiding the folded region, ramify through the
Gondwana beds or penetrate the basement in the Karroo region, the
Zambezi Valley, Tasmania, Antarctica, the Parana basin, and possi¬
bly Guiana, and that were injected during or immediately after the
eruptive phase, probably during the Liassic.

GEOLOGICAL HISTORY OF THE AFRO-AMERICAN LAND MASS 107

THE JURASSIC TRANSGRESSION

The upward transfer of these enormous volumes of magma led
to instability along the borders of Gondwanaland and to the trans¬
gression of the Liassic and Jurassic ocean across its margins, and the
breaking-up of that continent seemingly dates from this period. We
find fossiliferous marine beds with dolomite and gypsum in Tunis
and Abyssinia, a wide development of Jurassic through British East
Africa, Tanganyika Territory, and Madagascar, while on the oppo¬
site side of the land-mass about the border of Chile and Argentina
the Liassic is characterized by eruptive matter — rhyolite, dacite,
and spilite — while marine beds of this epoch covering many stages
were laid down along an enormous stretch of the Andine region.

THE CRETACEO-TERTIARY

It is a striking fact that no early marine Cretaceous should
fringe the coasts either in the section between Bahia Blanca and
Bahia or that between Cape Agulhas and Angola, suggesting, indeed,
that the two continents may have still been united at the commence¬
ment of that epoch, although Madagascar and India must almost
certainly have parted from Africa by that time. The early Cre¬
taceous ocean nevertheless assuredly trespassed over the southern
extremity of Africa, and also covered parts of Neuquen and the
Andine region.

The mid-Cretaceous, so far as can be elucidated the Turonian,
saw a great renewal of orogenic movement in Africa, directed east-
west over the wide belt traversed by the earlier Cape foldings, with
considerable marginal fracturing both there and in the Natal-
Zululand coastal area. Evidence of synchronous crustal movements
has been discovered in Neuquen, with arc-like flexures bridging the
gap between the Gondwanides and the (posthumous) Andine fold¬
ings, while correlated flexures strike southward through Chubut,
curving eastward to the mouth of the Rio Deseado, disturbances
that have been called the “ Patagonides ” by Windhausen.29 Then
came a period of extensive erosion, after which the later Cretaceous
ocean transgressed into those regions, entering by an arm situated
between the Sierras of Buenos Aires and the Patagonian platform,
as far inland as the Sierra Pintada.

The weight of evidence would ascribe the base-leveling in the
Sierra de la Vent ana and the accumulation of the ‘ ‘ high-level gravels
to the well-established Eogene transgression that followed the first
phase of the Andine movements, while the upheaval thereof would
synchronize with the second phase and, preceding the “Parana”
ingression, date from the early Pliocene. The correspondence with
the southern Cape is hence remarkably close.

28 Windhausen (1924), p. 202.

108 GEOLOGICAL COMPARISON OF SOUTH AMERICA WITH SOUTH AFRICA

A wealth of information will be found in the writings of Wind-
hausen on the palaeogeography of northern Patagonia, the outstand¬
ing item being the fact that the Cretaceo-Tertiary (San Jorge) fauna
of the Rio Negro and Chubut is of South Atlantic and Antarctic
facies and does not show North Atlantic affinities.

The little that is to be gleaned from Eastern Brazil is confirma¬
tory. The late Tertiary lacustrine deposits stand at a relatively high
level, e.g.y Curitiba, Sao Paulo, and near Diamantina, and point to a
comparatively recent uplift, while the physiography of the Parahyba
Valley between Sao Paulo and Rio de Janeiro strongly suggests that
the lengthy crystalline chain of the Serra da Itajuba running parallel
to the coast is a fault scarp with downthrow on the ocean side. In
South Africa, too, the general movement of the continent has been
in an upward direction to the amount of several hundred meters.

THE ANDINE MOVEMENTS

Under the displacement hypothesis the South American conti¬
nent is viewed as having proceeded to drift westward during the
latter part of the Mesozoic, crumpling up in its path the marine sedi¬
ments bordering the western side of the Brazilian “shield, ” a process
that led to the extravasation of magma and the injection of hypabys-
sal and plutonic matter into that belt of extreme compression and of
upheaval. The Tertiary foldings and overthrustings, directed usually
toward the east, that characterize the Cordillera and extend from
Venezuela to Terra del Fuego, find their explanation in logical fashion
under this hypothesis, the eruptive matter being regarded not as the
cause of such movements, but as the product of such compression
upon the zone underlying this belt of crumpling, an action that has,
moreover, not yet ceased.

Hindered by the birth of these western ranges, the drainage of
the continent would have been reversed, while the spasmodic ele¬
vation of the chains would have caused oscillations in the level of the
slowing earth-block and encroachings and retreats of the waters of
the Atlantic. In the broadening gap between Africa and South Amer¬
ica the presumably basaltic ocean-floor with its accumulating mantle
of pelagic deposits would normally have been in tension, and found¬
ering of sections thereof is a possibility that can be invoked to explain
the volcanicity of the South Atlantic basin, as exemplified by its
many volcanic islands.

Much could be written on the Tertiary history of this vast ocean
basin having an intimate and vital bearing on the subject under
review, but enough has, I venture, been set down to impress the
reader with the exceptionally illuminating and outstanding character
of this stimulating theory of earth structure, undoubtedly the most
fascinating of geological hypotheses to-day.

CHAPTER VII

BEARING ON THE DISPLACEMENT HYPOTHESIS

While the general geological resemblance between those portions
of the two continents that face the South Atlantic basin has long
been perceived, the outcome of these present studies is essentially to
emphasize this geological parallelism, which is nothing less than
extraordinary, considering the enormous stretches of ocean parting
these two land-masses.

Such points of resemblance have now become so numerous as
collectively almost to exceed the bounds of coincidence, while they
are, moreover, confined not to one limited region nor to one epoch,
but implicate vast territories in the respective land-masses and
embrace times ranging from pre-Devonian almost to the Tertiary.
Furthermore, these so-called “coincidences” are of a stratigraphical,
lithological, palaeontological, tectonic, volcanic, and climatic nature.

Of prime importance , moreover , is that evidence obtainable from the
study of the phasal variations displayed by particular formations when
traced within their respective continents.

In illustration, let us consider the case of two equivalent forma¬
tions, the one in South America beginning on or near the Atlantic
coast at A and extending westward to A' and the other in Africa
starting similarly near the coast at B and stretching eastward to B'.
Then it can be affirmed that more than one such instance can be
designated, where the change of facies in the distance A A' or BB' is
greater than that found in AB, although the full width of the Atlantic
intervenes between A and B. In other words, these particular forma¬
tions along the two opposed shores tend to resemble one another
more closely than either one or both of their actual and visible
extensions within the respective continents. With the multiplication
of such examples, drawn from more than one geological epoch, such
a singular relationship can no longer be regarded as wholly fortuitous
and a definite explanation therefore has accordingly to be sought.
An analysis, moreover, shows that this unexpected tendency is
equally marked, whether the formations involved be marine, deltaic,
continental, glacial, eolian, or volcanic.

If, on the other hand, the two land-masses are pictured as having
been moved closer together, as in Figure 7, a great number of obser¬
vations and deductions are now found to be brought into apparent
harmony, and these possible “coincidences” are disposed of in the
simplest fashion.

This is precisely what the displacement hypothesis effects, there¬
by providing a simple explanation of many otherwise puzzling

109

110 GEOLOGICAL COMPARISON OF SOUTH AMERICA WITH SOUTH AFRICA

observations. The fact that many eminent scientists have cast doubt
upon its geophysical possibility should not be permitted to cloud the
issue any more than that the existence of former “land bridges’'
should be denied because of cogent objections based upon the doc¬
trine of isostasy.

It is not proposed to discuss here the physical basis of that
hypothesis, nor is it desired to deal with this problem as a whole,
such as has been done by Wegener.30 The intention is merely to set
forth some of the data regarding Africa and South America and to
state the conclusions to be drawn therefrom, that are distinctly
awkward of explanation under the current and orthodox view of
“land bridges,” but which, on the contrary, appreciably favor the
“hypothesis of continental disruption.” Incidentally, some few
observations will be made having a bearing upon other parts of
Gondwanaland, that in turn suggest lines of future research in those
particular countries.

Of prime importance is the extraordinarily close correspondence
in the outlines of the opposed shores of the two continents, as has
been pointed out and discussed by others long before Wegener, and
which is particularly marked when comparison is made not with
maps, but on the face of a terrestrial globe. Next is the presence of the
central Atlantic rise beneath the ocean, with its surprisingly sym¬
metrical position nearly midway between the Old World and the New.

Interpreted mathematically , the great regularity of these three
features, extending through the entire length of the South Atlantic,
would betoken an enormously high probability that such features had
owed their origin to one and the same set of tectonic forces at a
relatively late geological period. Upon this rise are, furthermore,
aligned certain of the volcanic islands of the southern Atlantic. This
otherwise profitable subject must, however, be relinquished in favor
of the more momentous geological aspect.

Commencing in the south, the following relationships can be
considered as more or less established :

* (I) The section south of Bahia Blanca and that below the Zuurberg

in the Uitenhage district show several points of agreement in that :
(a) The upper Triassic (i) is predominantly of volcanic origin, (2)
rests discordantly upon Permian or older beds that are affected by
Permo-Triassic movements, (3) is influenced by mid-Cretaceous
disturbances following more or less the older tectonic axes, and (4)
is overlain by marine Cretaceous and Tertiary, the former of which
contains variegated clays and is in places gypsiferous. In the Cape
the volcanics are, however, basic, in Argentina largely acid, though
in Mendoza and San Juan basaltic flows are represented. ( b ) The
lower Cretaceous in northwestern Neuquen on the southern side of

30 Wegener (1924).

BEARING ON THE DISPLACEMENT HYPOTHESIS

111

the “ Gondwanides ” contains a typical “Uitenhage” invertebrate
fauna, this being the only part of South America where such a
faunal assemblage has yet been found, and like that in the Sundays
River Valley has been tilted before late Cretaceous times. ( c ) There
are great developments of nearly flat marine Tertiaries from Eocene
to Pliocene in age, in which most strikingly an “Atlantic” fauna is
not at all or only partially represented.

(II) The ranges north of Bahia Blanca undoubtedly correspond
with the Cape Fold ranges, in each case showing: (a) Intense fold¬
ing, with overturning toward the north or northeast, strata up to the
Permian being involved. ( b ) The quartzites of the Sierra de la Ven-
tana correspond lithologically with the Table Mountain sandstone
of the region about Mossel Bay and George, (c) The fossiliferous
Devonian is like that of the latter region, but the equivalent of the
Witteberg series is composed of greywackes instead of hard white
quartzites. ( d ) The thick, folded and cleaved glacials in Argentina
duplicate the characters of the Dwyka tillite and are conformable
with the beds below, as in the Cape south of latitude 33 ° S. (e) In
Argentina, dark shales overlie the glacials, as in the Cape, and pass
up into beds like the Ecca of the southwestern Karroo, only some¬
what more quartzitic, but in the first-named, just as in Pondoland,
the horizon with Mesosaurus is not recognizable. (/) Dolerite intru¬
sions are absent in each case, (g) Consolidated ferruginous “gravels”
rest on bevels cut across the folded beds on the northern flanks of the
Sierra de la Vent ana and duplicate in most extraordinary fashion
the early Tertiary “high-level gravels” of the south of the Cape,
having similarly been raised and dissected at a subsequent date.

( h ) Traced northwestward from Sierra de la Vent ana into San Juan
and Jachal, the lower Devonian quartzites have become darker and
less like the Table Mountain sandstone, the fossiliferous slates
greener, the equivalent of the Witteberg is apparently represented by
grits and greywackes, the glacials now rest unconformably on the
older divisions and show characters very different from those in
the Cape, at the same time becoming compound; tfie plants
include northern Carboniferous forms, while the succeeding strata,
the equivalent of the Ecca, become quite unlike those of the west¬
ern Cape.

(III) To the northeast of the Sierra de la Ventana the “Gond-
wanides” are fading out, and at Olavarria and Tandil the pre-
Devonian rocks are only slightly affected by them, though a folding
transverse thereto, trending northeastward, can be made out, thus
paralleling the conditions between Clan william and Namaqualand.
Closer comparison is impossible, since the Pampean of the lower
ground round about conceals these older groups.

(IV) Comparing the region stretching from Uruguay to Minas

112 GEOLOGICAL COMPARISON OF SOUTH AMERICA WITH SOUTH AFRICA

in Brazil with that between Clan william and the Kaokoveld, we find :
(a) The almost horizontal Furnas sandstone of Parana is similar to
the equivalent Table Mountain sandstone of Clan william and Van
Rhynsdorp. (b) Each is thinner and softer than in the south and each
carries small quartz pebbles, (c) Each is succeeded by the marine
Devonian shales with calcareous nodules — Ponta Grossa shales and
Bokkeveld beds — with closely allied austral faunas, (d) The soft
Tibagy sandstone with Spirifers duplicates the “ Fossiliferous sand¬
stone” of the Bokkeveld of Ceres and Clan william, (e) The base of the
Itarare glacials is unconformable and transgressive, exactly as is the
case with the Dwyka in Calvinia, which stratigraphical relation is
maintained toward the north. (/) There is irregularity in the charac¬
ter and thickness of the glacials in each country, owing to the
uneven nature of the floor, etc. (g) The glacials are absent at the
base of the Gondwana system in Rio Grande do Sul and in Santa
Catherina, just as in parts of the Transvaal. Qi) A southeasterly
source is presumed for the Brazilian glacials, a northerly, north¬
easterly, and perhaps northwesterly origin for those in the western
Cape and in Southwest Africa, (i) The Iraty shales are identical
lithologically and palaeontologically with the White band of the
Dwyka, each containing the reptile Mesosaurus, not known in other
parts of the world. The South African formation is fully developed
from Robertson across to Grahamstown and northward to Mariental,
but is not represented in Natal, the Transvaal or about Palapye; the
South American extends from Uruguay to Sao Paulo and westward
into Paraguay, but is unknown in the bore-holes in Argentina west
of the Parana River or in Bolivia. Thus the basin within which this
uncommon type of originally organic sulphureted mud was deposited
is fairly well defined and must have formed an estuary opening
probably to the north, where the facies becomes calcareous, a con¬
clusion to which the presence of a marine phase in the glacials in
Parana and Southwest Africa would give support, (j) An important
difference is to be found through the Brazilian Bonito or “coal
measures ” underlying this horizon, whereas the Natal and Transvaal
Ecca “coal measures” succeed the latter, but I should like to record
that in the western Karroo I have found a zone of gray fissile
sandstones such as is unrepresented farther to the east or northeast,
in corresponding position in the upper Dwyka shales. Presumably
the Bonito is a deltaic phase that “invaded” the basin in which
the “post-glacial” deep-water shales were being laid down, (k) The
Estrada Nova, which shows resemblance to stages II and III of the
Paganzo, but not to the presumably equivalent horizon of Bolivia,
strongly recalls the Ecca of southwest Africa, which again is widely
different from that of the Cape, Transvaal, and Rhodesia. Silicified
wood is common in both countries, but marine mollusca of this age

BEARING ON THE DISPLACEMENT HYPOTHESIS

113

have not yet been found in South Africa. (/) The higher Permian
beds are apparently absent from the Parana basin and from South¬
west Africa, which has seemingly been the result of the positive
earth movements at the close of the Palaeozoic, (m) The Sao Bento
series is pseudo-conformable to the underlying strata in the Parana
basin, just as the Stormberg series rests without angular break upon
the upper Beaufort series in the north of the Orange Free State or
upon the Ecca in the central Transvaal, (i) Each series transgresses
across the lower Gondwanas, i.e., along the margins of the Parana
basin and in the region lying to the north and northeast of the Cape
Province; (2) strata with the “ Thinnfeldia flora” are developed
toward the base, almost solely in the south, i.e., in the Cape-Basuto-
land region and in western Argentina and the fresh- water crustacean
Cyzicus (. Estheria ) draperi is common to both these areas; (3) the
brilliantly colored Rio do Rasto parallels the Stormberg Red beds and
Bushveld marls and like the latter formations contains dinosaurian
remains belonging to allied forms ; (4) the Botucatu and uppermost
portion of the Rio do Rasto agree lithologically with the Cave-
Bushveld-Forest sandstone, all of which have been formed largely
by eolian agency under an arid climate; silicification of the sand¬
stones is common; (5) the succeeding and widespread volcanics are
interbedded in their basal portions with thin sandstone bands or
tufaceous sandstones; (6) the only places where the volcanics form
the actual coast are near Torres and in the Kaokoveld respectively ;
(7) the lavas are basalts with but little olivine or else basaltic andes¬
ites, but, while ophitic and subophitic structures are the rule in the
Cape, a porphyritic structure is occasional in southern Rhodesia and
is dominant both in the Kaokoveld and in the Parana basin, while
tuffs are rare. They show bands of pipe-amygdaloid and were evi¬
dently poured out in rapid succession, apparently under a dry climate
and presumably from fissures, for except in the Basutoland region
volcanoes are practically unknown ; (8) these effusions terminate the
succession in both countries, (m) Widespread injections of dolerite
characterize the flat -lying Karroo of the Cape, Natal, and southwest
Africa and also the Parana basin, but are not found in the south of
the Cape, northern Transvaal, or Southern Rhodesia generally, nor in
southern or western Argentina. ( n ) Marine Jurassic and Cretaceous
beds are absent from along the opposite coasts. (0) Kimberlite and
melilite-basalt of presumably late Cretaceous age pierce the strata
in the form of pipes both in South Africa (for example, in Namaqua-
land and the Gibeon district) and in eastern Brazil (for example, in
the Serra das Lages 100 km. from Rio de Janeiro,31 and at Patos, in
the western half of Minas, where a neck penetrates Triassic sand¬
stone). (p) The Cretaceous of east-central Brazil is largely a conti-

31Rimann (1915).

114 GEOLOGICAL COMPARISON OF SOUTH AMERICA WITH SOUTH AFRICA

nental deposit covering a huge region in the interior, overlapping the
Sao Bento volcanics and paralleling in certain ways the extensive
Kalahari beds of southwest Africa, (q) The detrital diamonds of south¬
west Africa that have been derived from Tertiary marine beds near
Luderitz are quite unlike those won from the kimberlite pipes of
South Africa, but show crystallographic and physical points of
resemblance with the gems obtained in eastern Brazil from gravels
or from pipes, such as the Boa Vista Mine, piercing the Espinago
quartzites and apparently of pre-Gondwana age. (r) The pre-Devo¬
nian beds consist of quartzites, limestones, and slates folded along
axes roughly parallel to the respective coasts and injected in places
by granitic bodies, i.e., the Bambuhy and Assunguy series, at inter¬
vals from Bahia to Uruguay, and the Nama system from Luderitz
to Cape Agulhas. (5) Brouwer has called attention to the presence
of several centers of alkaline rocks, both plutonic and effusive, on
either side of the Atlantic, for example, in Southwest Africa the
important group of foyaites of the Granit Berg, etc., and the phono-
lites of the Klinghardt Mountains near Luderitz, and in Brazil the
well-known Poqos de Caldas north of Sao Paulo, the various similar
occurrences in the State of Rio de Janeiro, such as the Serra de
Gericino, Serra de Tingua, Cabo Frio, etc.

(V) Proceeding farther north we find: (a) Opposed to the dis¬
turbed area of Cretaceous and Tertiary of Angola and Loanda are
those of Bahia and Sergipe, in which their equivalents, with similar
faunal elements of the Atlantic and Mediterranean types, display
somewhat less tilting, (b) Inland therefrom in Brazil are the folded
Permian and probably Carboniferous Estancia beds, with some
resemblances to the Kundulungu of the lower Congo region, while
beneath the latter lies a great calcareo-dolomitic formation, which
may perhaps be compared with the ancient limestones of Bahia.

(VI) Farther north is found a belt of Cretaceo-Eocene along the
coast from Natal westward that rises up to form the plateau along
the boundary of Ceara with Piauhy and is seen again in the northern
part of Maranhao. These strata can be compared with the beds of
approximately similar age in the coastal portions of Gold Coast,
Dahomey, and Cameroons, extending up the valleys of the Niger and
Benue and occupying a wide area to the north. In Nigeria the
Cretaceous is somewhat folded and faulted. Reference might be
made to the well-known volcanic line of the Cameroons that extends
southwest ward into the ocean, in view of the presence off the comer
of Brazil of the phonolite island of Fernando Noronha.

(VII) The Gondwana outlier of Maranhao and Piauhy consti¬
tutes a fairly close parallel with the development known as the Lubi-
lache in the western part of the Congo Basin in ( a ) the absence of the
glacial group, (b) the absence of coals, (c) the equivalence apparently

BEARING ON THE DISPLACEMENT HYPOTHESIS

115

of the upper red sandstones of Brazil with the cream and red friable
sandstones in the Congo. Mesozoic volcanics are, however, not yet
known in west-central Africa, whereas the Brazilian strata are over-
lain by basalts and penetrated by dolerites.

(VIII) The Silurian and Devonian strike south-south west ward
through the Sahara and southwestward through West Africa, with
isolated patches of the latter system in Gold Coast Colony, and are
apparently not much disturbed generally, a condition that can be
paralleled with the corresponding systems forming the syncline of
the lower Amazon Valley resting on the Archaean granite, with trend
oblique to the coast -line, the more so in that the Devonian in each
case includes, in addition to European elements, some North Ameri¬
can forms, and also displays certain important affinities with the
austral fauna. Presumably land lay to the south, and along that
Devonian coast migration was possible toward Europe in the one
direction and toward Amazonas, Matto Grosso, and Bolivia in the
other. A point that might be noted in view of the diamondiferous
deposits of the Guianas is the frequency with which that gem occurs
in the coastal belt of West Africa, e.g., in Liberia and Gold Coast.

While the above can be taken as merely summarizing the evidence
on the subject, it will be clear to all acquainted with the literature
that many other points of similarity or else of analogy could readily
be discovered in the geology of these two land-masses. Sufficient, I
venture to think, has already been set down to bring out the aston¬
ishing geological agreement between more or less comparable sections
of the respective coastal zones, from which it will be conceded that
the evidence so far would distinctly appear to favor the displacement
hypothesis rather than orthodox ideas. It is nevertheless highly
desirable that more impartially minded persons should criticize the
data here given and judge whether those amazing resemblances have
been correctly interpreted or whether some more rational explana¬
tion for them could not be formulated.

Accepting provisionally this hypothesis , it will next be instructive
to attempt some graphic representation thereof.

Regarding the various possible dispositions of the continental
masses, it can first of all be remarked that actual contiguity of the
opposed shore-lines can most definitely be ruled out, and, secondly,
that even apposition of the borders of the continental shelves, as
favored by Wegener, may perhaps hardly be warranted, for utilizing
the line of reasoning based on phasal variation , the differences actu¬
ally noticed between the various facies of the equivalent formations
where they come closest together are of such a degree as to demand
a fairly wide gap. One of the order , perhaps of from 400 to 800 km.,
would indeed seem to he needed , if all the observed phenomena are to
he satisfactorily accounted for.

116

GEOLOGICAL COMPARISON OF SOUTH AMERICA WITH SOUTH AFRICA

- Cretaceous and
l Eocene

✓

. Condwana

«*— • —

Silurian , Devonian'
and Carboniferous

Late Eozoic and
e a r/y Pa la e oz oic ■

• Gondwanides and
Cape fold in 3s

v V

V V

Granitic basement

PosPTriassic uplifts

Fig. 7 — Suggested continental restoration under the Displacement Hypothesis.

- Limit of Mesosaurus

— . - And me fold mss

- BrasiUdes and

Post-Nama foldings

BEARING ON THE DISPLACEMENT HYPOTHESIS

117

Such is schematically represented in Figure 7, which is tentatively
suggested as perhaps best meeting the needs of the case, though the
intervening space is actually a little less than the phasal variations
would rightly demand.

Further critical comparative studies should enable a better ori¬
entation to be made, the diagram advanced being admittedly only
a first approximation. Granted, too, that such crustal slipping could
have taken place, it must not be overlooked that some regional dis¬
tortion might have resulted during the drifting apart of the floating
continental blocks, an action inferred from the inflection of the
Andine foldings in the neighborhood of Cape Horn.

It will be noticed that in this figure the Falkland Islands have,
following the discussion in Chapter VI, been moved up into a posi¬
tion between Cape Town and La Plata. Only now can the remark¬
able correspondence of the various fold-lines, and even of the more
moderate archings, of different ages be properly appreciated. The
rupture of the Afro-American mass is also more than hinted at in the
strict parallelism of the zigzagging of the two coast-lines near Rio
de Janeiro and Angola respectively. It is surprising, too, though not
deliberately arranged, that the space between the two shores should
correspond so closely in its two boundaries with the plan of the
“central ridge” of the South Atlantic. These two sections of coast¬
line, it should furthermore be noted, are composed of crystalline
rocks, whereas both to the north and south considerable stretches
can be found where late Tertiary and Quaternary marine sediments
fringe the shores and consequently tend to obscure the original out¬
lines of the supposedly fractured masses.

Further elaboration is hardly necessary, and the diagram is
accordingly left to the criticism of the reader.

CHAPTER VIII

CONCLUSIONS

Throughout this work the intention has been to detail the geo¬
logical peculiarities of the opposed sections of the two land-masses,
to point out their resemblances and differences, and to draw such
legitimate conclusions in regard to the geographical, climatic, and
other circumstances in each country as the facts would appear to the
writer to warrant, though irrespective of any particular theory of
continental union during the past, for that they were so united is
indicated by a wealth of evidence of a practically indisputable
character.

But, having proceeded thus far, one could scarcely avoid making
use of these data and indulging in a certain amount of speculation as
to their possible manner of union during the later Palaeozoic and
early Mesozoic eras. Such an analysis, it can be affirmed, does not
favor the notion of one or more relatively narrow connecting links or
“land bridges” lasting down into the early Mesozoic, but on the
contrary supports the presumption of some continuous land area
embodying those sections of Gondwanaland that are now represented
in the two continents. It furthermore strongly favors the admittedly
revolutionary idea that geographically these two portions were
appreciably closer in the past; indeed, the evidence is, I think, of
sufficient weight to warrant such a viewpoint being adopted, as a
working hypothesis at any rate. Upon studying the remnants of
Gondwanaland in the other continents — India, Australia, etc. — we
find the facts and the deductions therefrom in similar accord, and
the impression becomes decidedly strengthened that the displace¬
ment hypothesis, if not an actual explanation of the phenomena,
would at least seem to contain more than a germ of the truth,
despite its revolutionary and heterodox nature and apparent lack
of agreement with geophysical considerations.

Nevertheless, as already remarked, geological evidence almost
entirely must decide the probability of this hypothesis, for those
arguments based upon zoo-distribution are incompetent to do so,
being as a rule equally, though more clumsily, explicable under the
orthodox views involving lengthy land connections afterward sub¬
merged by the oceans.

The hypothesis sets forth to explain in simple and logical fashion
a host of problems — geological, palaeontological, tectonic, climatic,
and biological — that have hitherto proved difficult or impossible of
satisfactory solution, and is incidentally serving to stimulate geo-

118

CONCLUSIONS

119

logical thought in fashion almost unparalleled in the history of
that science. For example:

(1) It condenses all the sections of Gondwanaland with their
markedly similar formations and geological histories within the
compass of one moderately sized continent , instead of demanding a
land-mass very much larger than Eurasia.

(2) It brings into close association away from the equator all the
areas glaciated in the “Permo-Carboniferous” and thus succeeds in
eliminating an outstanding difficulty in necessitating somewhere or
other a refrigeration in the subtropics or tropics, a trouble inherent
under any other hypothesis, even in those postulating a wide move¬
ment of the South Pole.

(3) It can explain the apparent non- synchronism of glaciation in
the several sections and many other observed peculiarities as pri¬
marily due to the progressive migration of the main ice center or
centers.

(4) It simplifies the problem of the distribution of the ‘ ‘ Glossop-
teris ” and “ Thinnfeldia ” floras.

(5) It brings together the wide areas over which arid conditions
seem generally to have prevailed at the close of the Triassic. In
making a review of this problem nothing is more conspicuous than
the tendency under the orthodox viewpoint of overlooking the enor¬
mous improbability that over widely separated parts of the globe,
situated in different latitudes and longitudes and under totally
differing oceanic environments (and therefore of atmospheric dis¬
tributions) there should have coexisted huge areas throughout the
entirety of which the climate should consistently have at any one
epoch been either frigid or pluvial or arid.

(6) It assembles the earlier Mesozoic lava-fields.

(7) It would explain Gondwanaland as a well-defined and almost
isolated unit down to about the end of the Jurassic epoch, after which
the continental mass is viewed as proceeding to break up and the
sectors to begin drifting apart, with the Cretaceous ocean progres¬
sively penetrating between the blocks and generally coming to over¬
lap their borders in the fully established marine transgressions of
the late Mesozoic.

In the hypothesis as formulated by Wegener, the New World is
regarded as having parted from the Old up the full length of the
Atlantic from south to north at quite a late stage in the Tertiary, *
against which supposition many objections could be raised. Else¬
where32 I have tentatively suggested the radically different concep¬
tion of two such parent continents, that to the south being Gond¬
wanaland, which, by impinging on each other, gave rise to the enor¬
mously extended orogenic structures made by the Atlas, Alps,

32 Du Toit (1921a).

120 GEOLOGICAL COMPARISON OF SOUTH AMERICA WITH SOUTH AFRICA

Carpathians, Caucasus, Himalayas, etc., or, as Suess has called
them, the “Posthumous Altaides. ” Concentrating attention upon
the southern continent, it can be pointed out that one of the deter¬
mining factors in the conjectured breaking up of the mass may have
been the development around the continental “shield” of the
peripheral trough of subsidence or “fossa, ” within which sedimenta¬
tion had proceeded through lengthy periods during Palaeozoic, Meso¬
zoic, and even Cainozoic times, whereby an engirdling zone of crustal
weakness would have been produced favoring the centrifugal separa¬
tion postulated.

These encircling oceanic deposits would thereafter have been
pushed up into folds in advance of the drifting crustal sectors, a
process that would ultimately have served to arrest their outward
movement, for, in conspicuous fashion, excluding “Angaraland, ” all
the known portions of Gondwanaland now lie within a practically
closed orogenic ring constituted by the Atlas, south European,
Iranian, and Himalayan folds on the north, the Malay, Polynesia,
and New Zealand crumplings on the east, the west Antarctica belt
on the soutlp and the Andine flexures on the west, curving eastward
into Venezuela. Along certain sections of this “orogen, ” to use
Kober’s term, intense compression and overthrusting then took
place, accompanied by considerable magmatic activity.

Such a view would, moreover, serve to explain the temporary
reunion of certain of the continents at some stage in the Tertiary, as
the facts of zoographical distribution would apparently demand. A
rather similar process is conceived to have operated in the Northern
Hemisphere, where the continental fragments lie within a great oval
ring of mainly Tertiary foldings, from Mexico to Alaska, Japan, the
Himalayas, and onward as before. These two orogenic belts are
pressed together in the section extending from the West Indies to
the East Indies, in which two regions distorted arcs with marked
inflections have originated from their supposed mutual interference.
As will be observed from a map, these two orogenic “fossae, ” when
rolled out into one plane, come to resemble a figure 8, while the
remainder of the surface of the globe constitutes the immense
basin of the Pacific, along the margins of which the two fold-systems
have crowded.

SOME GENERAL REMARKS

These pages have of necessity dealt in very summary fashion
with this fascinating subject, more particularly as related to those
territories beyond the respective opposed regions known personally
to the writer. It is therefore to be hoped that scientists acquainted
with those particular outside regions may be induced to set down
their observations on those areas, supporting or else refuting the pre-

BIBLIOGRAPHY

121

sumptions here put forward on behalf of this hypothesis, since a
strict and impartial criticism is indeed required if this riddle in early
history is to be deciphered. The cooperation of geologists, palaeon¬
tologists, zoologists, botanists, and physicists is urgently needed, the
discussion advanced here dealing admittedly with only a very
limited, albeit extremely important, section of the globe, from which,
under the eclectic hypothesis of crustal instability, corroborative or
destructive evidence might reasonably be expected. By virtue of
their enormous lengths of opposed coast-line and extraordinary geo¬
logical parallelisms, the two most favored continents from which evi¬
dence is to be drawn would appear to be Africa and South America,
and, should the details herein set forth appear to be worthy of
serious consideration, it is to be hoped that more detailed investiga¬
tions may shortly be instituted elsewhere on the two sides of the
Atlantic for the purpose of clearing up some of the many crucial
questions that must be regarded as sub judice.

Even if the facts collected should cause the displacement hypoth¬
esis to be discarded, the researches made through its stimulus would
have served a most useful purpose in establishing data for the fuller
comprehension of this problem of the past history of our planet.

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Rassmuss, J.

1918.

Der Siidrand der Puna de Atacama (NW. Argentinien). Leipzig.

Investigation de la estructura tectdnica de la Cuenca imbrifera del
Rio de la Rioja. Minist. Agricult. Argentina, bol. 17, serie B.

126 GEOLOGICAL COMPARISON OF SOUTH AMERICA WITH SOUTH AFRICA

Rassmuss, J. — Continued.

1921. Observaciones geologicas en Salta. Minist. Agricult. Argentina, bol.

4» P* 25-

1922. Apuntes geoldgicos sobre los hallazgos de Carbdn al sur del Lago
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1922a. La Cuenca de Marayes. Ibid., bol. 32, serie B.

Reed, F. R. C.

1925. Revision of the Fauna of the Bokkeveld Beds. Annals S. African
Museum , XXII, pt. I, no. 2, pp. 27-225.

Rimann, E.

1915. Ueber Kimberlit und Alnoit in Brasilien. Tscher. Min. u. Petr. Mitt.
XXXIII, p. 244.

1917. A Kimberlita no Brasil. Annaes. Escola. Minas. Ouro Preto. no. 15.

1918. Estudio geologico de la Sierra Chica. Bol. Acad. Nacion. Ciencias.

Cordoba, XXIII, 2,pp. 129-202.

Rogers, A. W. and A. L. Du Toit.

1909. The Geology of Cape Colony. London.

Schiller, W., and H. Keidel.

1907. Ueber den Bau der argentinischen Anden. Sitz. Berich. K. K. Akad.
Wissen. Wien., Math-natur. Kl., CXVI, sect. I, pp. 649-674.

Seward, A. C.

1922. On Carboniferous Plants from Peru. Quart. Journ. Geol. Soc. London

LXXVIII, p. 278.

Seward, A. C., and J. Walton.

1923. On a Collection of Fossil Plants from the Falkland Islands. Quart.

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SlEMIRADSKI, I. VON.

1893. Eine Forschungsreise in Patagonien. Petermann’s Mitt., Bd. 39, pp.
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Small, H. L.

1914. Geologia e supprimento d’agua subterranea no Piauhy e parte do
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Sopper (Soper), R.

1914. Geologia e supprimento d’agua subterranea em Sergipe e no
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Stappenbeck, R.

1910. La Precordillera de San Juan y Mendoza. Anales. Minist. Agricult.
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1913. Apuntes Hidrogeologicos sobre el Sud-Este de la Provincia de Men-
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1927. Ueber T ransgressionen und Regressionen des meers und Gebirgsbildung
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APPENDIX

UPPER CARBONIFEROUS FOSSILS FROM ARGENTINA

F. R. Cowper Reed, M.A., Sc.D., F.G.S.
Sedgwick Museum, Cambridge , England

With four plates

129

GENERAL REMARKS

The fossils submitted to me by Doctor Du Toit from the Que-
brada del Salto, Barreal, San Juan, Argentina, are mostly preserved
in a tough purplish sandy mudstone rather than shale, with an
irregular subconchoidal fracture, and, though often fragmentary and
imperfect, are occasionally in a good state of preservation.

R. Stappenbeck,1 in 1911, recorded the following fossils from the
same locality and apparently from the upper of the two fossiliferous
horizons herein discussed, which he referred to the stage of Spirifer
supramosquensis , a Russian species which Nikitin regarded as
characteristic of the Gshelian :

Spirifer supramosquensis Nik.
Productus cor a D’Orb.
Productus lineatus Waag.
Productus pustulatus Keys.
Orthis sp.

Chonetes sp.

Platy stoma sp.

Pleurotomaria sp.

Euomphalus sp. aff. parvus Waag.
Orthoceras sp.

Cyathocrinus sp.

Bryozoa.

No description or figures of the species were given, and there
has not been, to the best of my knowledge, any later account of
the fauna.

In the succeeding descriptions the figures 7281 to 7376 represent
the catalogue numbers of the specimens, which are preserved in the
South African Museum at Cape Town.

DESCRIPTION

Fenestella aff. perelegans Meek

Most of the specimens of Fenestella in this collection are poorly preserved
and fragmentary and only in one case is the poriferous face well preserved.
In this specimen (7324) the branches are subparallel, the dissepiments
slender and equidistant, the fenestrules rectangular and oblong, being about
ip2 times as long as wide and 9 to 10 occurring in a distance of 10 mm.;
there are 4 to 5 rather widely spaced small cells to each fenestrule, one of the
cells usually lying at the base of the dissepiments, and the low median
carina bears a row of much smaller pores (or hollow tubercles) numbering
7 to 9 to each fenestrule. The reverse face is rather coarsely striated longi¬
tudinally. The poriferous keel occurs in many species of the genus and was
figured by McCoy2 in F. formosa from the Carboniferous limestone of
Ireland. But it is on upper Carboniferous horizons that this type of Fenestella
is most common, and we may especially compare our form with F. perelegans
Meek3 of the coal measures of Nebraska, but also recorded by Waagen and

1 Stappenbeck, Geol. Aufbau d. Vorkordillere, Geol. u. Palaeont. Abhandl. N. F.,
Bd. IX, Hefts, I9ii,pp. 31,32.

2 McCoy, Syn. Carb. Foss. Ireland, 1844, p. 201, PI. XXIX, Fig. 2.

3Meek and Hayden, Final Rept. Nebraska, 1871, p. 153, PI. V II, Figs. 3 to 3d.

131

132 GEOLOGICAL COMPARISON OF SOUTH AMERICA WITH SOUTH AFRICA

Pichl4 from the Producius limestones of the Salt Range. There are also
several allied Russian species from the upper Carboniferous, such as F.
saraneana Stuck.5 and F. eichwaldi Stuck.,6 and the author7 has described a
form allied to the latter species from the upper Carboniferous of Chitral.
F. laosensis Mansuy,8 from the Permo-Carboniferous of Indo-China, may
also be compared.

Fenestella sp. ind.

Among the fragments of zoaria of Fenestella occurring in the collection
there seems to be another species (7306, 7307) characterized by its finer
mesh-work, 12 to 16 fenestrules occurring in a distance of 10 mm. The
reverse face is longitudinally striated, but the poriferous face is unknown
and the affinities of the species are therefore uncertain.

Polypora aff. biseriata Ulrich

A species of Polypora is represented by several poor and fragmentary
specimens (7286, 7285, 7311, 7295, 7298). The one (7286) which has the
celluliferous face of the zoarium best preserved shows also portions of the
reverse face. The zoarium consists of subparallel, thick, straight branches,
frequently bifurcating and bearing two rows of rather large alternating cells,
with an additional one usually at the base of each dissepiment. Traces of
a median line of small nodes can be occasionally detected. The reverse face is
ornamented with 8 to 10 rather coarse longitudinal thread-like lines, and
is flattened for most of its length, but seems to swell up in places into low,
broad nodes. The dissepiments are short and thickened at their base and
form oval fenestrules of subequal size longer than wide but narrower than
the branches; about 7 occur in a length of 10 mm.

The relations of this imperfectly known species seem to be with P.
biseriata Ulrich9 and P. varsoviensis Prout,10 both from the Warsaw Forma¬
tion, Illinois.

Orbiculoidea saltensis sp. nov. (Plate XIII, Fig. 1)

Shell subcircular. Upper valve low, conical, with excentral apex situ¬
ated at about one-third of the diameter from posterior margin. Surface
ornamented with about fifteen coarse rounded subequidistant concentric
liras, mostly bearing small, low, closely placed, hollow tubercles, the whole
crossed by very delicate radial strias. Lower valve (incompletely known)
flattened or gently concave, with hollow, low, conical apex and a small
foramen at the end of a partly inclosed broad groove to posterior margin.

Dimensions — I (7335): Diameter, 20 mm.; height, c. 8 mm. II (7340):
Diameter, c. 27 mm. ; height, c. 9 mm.

Remarks — There are three specimens (7335, 7340, 7310) of this new
species, one of which (7335) has the lower valve showing the posterior
groove, though in a poor state of preservation. The other two are less perfect
and only show the upper valve. The peculiar tuberculation of the concentric
rugae seems to be an original and definite character, but it is only well seen

4Waagen and Pichl, Salt-Range Foss. (Palseont. Ind., Ser. XII, 1885), p. 777; PI.

LXXXVII, Figs. 1 to 3.

6 Stuckenberg, Mem. Com. Geol. Russ., vol. X, no. 3, 1895, p. 231, t. XX, Fig. 16.

6 Ibid., p. 234, t. XXII, Fig. 1.

7 Reed, Upper Carb. Foss. Chitral (Palasont. Ind., n.s., vol. VI, mem. 4, 1925), p. 19,
pi. II, Figs. 6, 6 a, 7.

8 Mansuy, Mem. Serv. Geol. Indo-Chine, vol. II, fasc. 4, 1913, p. 23, PI. I, Figs. 2 a to c .

9 Ulrich, Geol. Surv. Illinois, vol. 8, 1890, p. 592, pi. LX, Figs. 4, 4 a and 4 b.

10 Ibid., p. 593, PI. LX, Figs. 2, 2 a, and 2 b.

UPPER CARBONIFEROUS FOSSILS FROM ARGENTINA

133

in two specimens, the third (7310) being much crushed and distorted. The
relations of this species seem to be with Orbiculoidea missouriensis (Shu-
mard)11 of the upper Carboniferous rather than with 0. nitida Phill.

Productus lineatus Waagen (Plate XIII, Fig. 9)

This species,12 which is included by many authors in Productus cor a
D’Orb., is represented by one small complete specimen of a pedicle valve
(7365) and several fragments of larger shells. The synonymy of this species
has frequently been discussed,13 but to the author14 Waagen’s type seems at
any rate to mark a distinct variety of the form known as Productus cora in
the lower Carboniferous of Europe.

Productus curvirostris Scliellwien var. nov. barrealensis (Plate XIII, Figs. 4 a, 4 b)

Shell with strongly convex narrow, elongated pedicle-valve, having
prominent incurved acutely pointed beak projecting behind and over short
straight hinge-line. Ears small, triangular, gently convex, well marked
off from body by impressed line. Surface of valve ornamented with few
regularly distributed spinose tubercles, semirecumbent, widely spaced, and
arranged in a roughly quincunx order, with weak concentric rugae becoming
more marked on the flanks and with fine, irregular, undulating concentric
lamellose striae over the whole valve.

Dimensions — (7315): Length, 16 mm.; width (cardinal), 10 mm.;
height, c. 8 mm.

Remarks — This shell, which is represented by one well-preserved speci¬
men of a pedicle-valve (7315) and by a fragment of another may be regarded
as a variety of Productus curvirostris Schellw.15 of the Permo-Carboniferous
of Italy. Mansuy16 has also recorded this species from Indo-China. It is
undoubtedly allied to Pr. acute atus Mart., but is sufficiently distinct, as
Schellwien and others have pointed out.

Productus cf. juresanensis Tschernyschew

A fragment of a pedicle- valve of a species of Productus (7281) is too
imperfect for a satisfactory determination, but it appears to possess the
ornamentation of Pr. juresanensis Tschern.,17 and it may be compared with
it rather than with Pr. nebrascensis Owen,18 which is closely allied and is
also an upper Carboniferous species. Pr. scabriculus Mart, belongs to the
same group.

Productus ( Marginifera ) cf. echinatus Waagen

One imperfect pedicle valve (7364) appears to possess the external char¬
acters of Pr. (. Marginifera ) echinata Waagen,19 as figured by Waagen from

uSchuchert, Bull. 87 U. S. Geol. Surv., 1897, p. 280 (for synonymy and references).

12 Waagen, Salt Range Foss. I (Palaeont. Ind.), p. 673, PI. LXVI, Figs. 1, 2; PI.
LXVII, Fig. 3.

13Hayasaka, Science Rept. Tohoku Imper. Univ., ser. 2, Geol., 1922, pp. 86-93,

14 Reed, Up. Carb. Foss. Chitral, etc., Palaeont. Ind., vol. VI, mem. no. 4, 1925, p. 28,
PI. Ill, Figs. 12 to 14a.

15 Schellwien, Palaeontographica, XXXIX, 1902, p. 26, t. Ill, Figs. 12 to 14. Gortani,
Palaeont. Ital., vol. XII, 1906, p. 23, t. II, Figs. 1 to 3; id., Boll. Soc. Geol. Ital., vol. XXV,
1906, fasc. 2, p. 14, Fig. 7.

16 Mansuy, Mem. Serv. G60I. Indo-Chine, vol. II, fasc. 4, 1913, p. 32, PI. II, Figs.
9a toe; ibid., vol. Ill, fasc. 3, 1914, p. 16, PI. II, Figs, ioatoc.

17 Tschernyschew, Mem. Com. G60I. Russ., vol. XVI, no. 2, 1902, p. 620, t. XLVII,
Figs. 1, 2; t. LIII, Fig. 4.

18Schuchert, Bull. 87 U. S. Geol. Surv., 1897, p. 327 (for synonymy and references).

14 Waagen, op. cit., p. 727, PI. LXXVIII, Fig. 1.

134 GEOLOGICAL COMPARISON OF SOUTH AMERICA WITH SOUTH AFRICA

the lower Productus limestone of the Salt Range. The thin, recumbent
spines on the surface, becoming more upstanding or tubercular posteriorly,
and the transverse swollen shape of the valve are clearly preserved; the
broad short beak, hollowed umbonal slopes, and hinge-line can also be
distinguished. It had been labeled Strophalosia cf. indica Waag., but is
totally different from that species.

Productus ( Marginifera ) spinulo-costatus Abich var. nov. peregrina (Plate XIII, Fig. 2)

There is one fairly perfect pedicle- valve (7374) which might be regarded
as a variety of Productus ( Marg .) ornatus Waag.,20 but seems more allied to
Pr. (Marg.) spinulo-costatus Abich,21 of the Djulfa beds, and if better known
we might consider it to be a distinct species. The shell is transversely semi¬
elliptical, with a straight hinge-line, equal to, or nearly equal to, its width;
the pedicle-valve is strongly swollen, with a weak, broad median depression
down the middle; the beak is broad, rounded, obtuse, swollen, and incurved
and overhangs the hinge-line. The ears are small, triangular, depressed,
and sharply marked off from the umbonal slopes, which descend steeply to
them and are somewhat excavated. The surface of the valve is ornamented
with weak, low, rounded, indistinct ribs, somewhat discontinuous, being
mainly due to radially elongated recumbent stout spines arranged in a
roughly quincunx fashion, but widely spaced; there are about eight such
faint ribs on each side of the median depression, which bears only one short
similar rib arising at about half the length of the valve ; three to five small spi-
nose tubercles form an irregular line along the junction of the ears with the
body, and two to three more occur on the ears. Fine concentric striae cross
the valve, with a few stronger growth-lines becoming more marked on the
flanks.

From typical examples of Pr. (Marg.) ornatus it differs by its more
elongated recumbent spine bases, and thus more resembles the Armenian
species, Pr. (Marg.) spinulo-costatus , which Freeh22 and Hayasaka23 figure
also from China. Pr. walcottianus Girty24 may also be compared.

Chonetes cf. pseudovariolata Nikitin

Two small specimens of Chonetes in rather a poor state of preservation
seem to be comparable to Ch. pseudovariolata Nikitin,25 of the Gshelian stage
of Russia, rather than with Ch. lissarensis Diener,26 of the Zewan beds of
Kashmir; but such small and imperfectly known shells are almost impossible
to determine specifically.

Chonetes granulifer Owen (Plate XIII, Fig. 6)

One large specimen of a species of Chonetes (7319) shows the pedicle-
valve with the shell broken away from most of the middle part and the
outer surface only preserved on a small portion near the anterior margin.
It is transversely semi-elliptical in shape, with the cardinal angles slightly

20 Waagen. op. cit., p. 721, PI. LXXVII, Figs. 5 and 6.

21 Freeh and Arthaber, Palaeoz. in Hocharmenien, Beitr. z. Palaeont. u. Geol. Oesterr.
Ung., Bd. XII, 1900, pp. 262-264, t. XX, Figs. 5, 7, 8, and 9; Diener, Palaeont. Ind., n.s.,
vol. V, mem. 2, 1915, p. 82, PI. VIII, Figs. 13, a to d, PI. IX, Figs. 1 and 2.

22 Freeh in Richthofen’s “China,” Bd. V, 1911, p. 175, PI. XXVII, Fig. 2.

23 Hayasaka, Science Rept. Tohoku Imper. Univ. Ser. 2, Geol., 1922, p. 99, PI. IV,
Figs. 15 and 16.

24 Girty, Prof. Paper 58, U. S. Geol. Surv., 1908, p. 269, PI. XXI, Figs. 27, a and b.

“Nikitin, Mem. Com. Geol. Russ., vol. V, no. 5, 1890, p. 27, PL II, Figs. 1 to 4;
Loczy, Beschr. Palaeont. Stratigr. Result. Reise Graf. Bela Szechenyi in Ostasien
(Budapest, 1898), p. 73, t. Ill, Figs. 8 to 13.

26 Diener, Himal. Foss. (Palaeont. Ind. Ser. XV), vol. I, pt. 4, 1897, p. 19, PI. II,
Figs. 4 and 6; ibid., n.s., vol. V, mem. 2, 1915, p. 83, PI. IX, Fig. 3.

UPPER CARBONIFEROUS FOSSILS FROM ARGENTINA

135

pointed but not produced into ears. The cardinal margin shows seven to
eight small, obliquely directed spine-bases, the largest being at the cardi¬
nal angle. The body is gently convex, and the valve is not definitely flat¬
tened or depressed in the middle, a sinus being completely wanting. The
surface is covered with numerous fine, granulated, equal radial lines, fifty to
sixty occurring on the margin in a space of io mm., apparently increasing by
bifurcation and intercalation, and in all there must be at least 200 such lines
around the whole margin of the valve. The interior shows a low, narrow
median ridge extending from the beak for about one-third the length of the
valve, and separating weakly impressed flabellate diductor scars, on each
side and in front of which, to a distance of about three-fourths the radial
diameter of the valve, there are coarse, rather closely set papillae, somewhat
irregularly arranged in radial lines ; outside them there is a marginal band
of smaller, more regular, closer, and more numerous papilla (in both cases,
of course, shown on the internal cast as punctae) .

This shell in some respects seems to resemble Ch. variolata D ’Orb., 27
and especially its variety baroghilensis Reed28 from the upper Carboniferous
of Chitral, in its internal character, but it has no definite median flattening
or sinus. Many of the shells referred to Ch. granulifer Owen29 bear a closer
resemblance to our shell, though this specific name has been used in some¬
what a wide sense and still requires a detailed diagnosis and strict limita¬
tion, but it is an indication of an upper Carboniferous horizon.

Camarophoria cf. mutabilis Tschemyschew?

Two crushed and imperfect valves (7327, 7352) of a rhynchonelloid
shell having three to four ribs in the sinus and on the fold and four to five on
each side seem to be comparable with the variable species Camarophoria
mutabilis Tschem.,30 typically occurring on the Schwagerina horizon of
Russia and also recorded from Indo-China by Mansuy.31

Spirifer cf. supramosquensis Nikitin (Plate XIV, Fig. 1)

Stappenbeck32 has already recorded Spirifer supramosquensis from this
locality in Argentina. It is characteristic of the Gshelian, according to>
Nikitin.33 There is one specimen (7316) in the present collection which,
seems indistinguishable from this species, and especially resembles the
figure of the shell from the Urals referred by De Verneuil34 to Sp. crassus
De Ron., but considered by Nikitin to be identical with Sp. supramosquen¬
sis. The shells which Hayasaka35 and Mansuy36 respectively figure as Sp.
nikitini Tschern. from the upper Carboniferous of Manchuria (in associ¬
ation with Sp. supramosquensis) and from the Productus limestone of Indo-
China bear a considerable resemblance, and Hayasaka remarks on its like¬
ness to the American Sp. mexicanus Shum. of the upper Carboniferous.

27D’Orbigny, Voyage dans l’Amerique Merid. Ill, pt. 4, 1842, p. 49, PI. IV, Figs. 10
and 11. Kozlowski, Brach. Carb. Super. Bolivie, Ann. Pateont. IX, 1914, p. 55, PI.
VIII, Fig. 16.

28 Reed, Up. Carb. Foss. Chitral (Pal. Ind., n.s., vol. VI, mem. 4, 1925), p. 40, PI. Ill,
Figs. 1 to 4.

29 Greene, Journ. Geol., vol. XVI, 1908, pp. 654-663, Pis. I-IV ; Girty, Bull. 544, U. S.
Geol. Surv., 1915, p. 59, PI. VI, Figs. 12 to 133.

30 Tschemyschew, op. cit., p. 491, t. XLV, Figs. 1 to 15.

31 Mansuy, op. cit., vol. II, fasc. 4, p. 90, PI. IX, Figs. 14a to c.

32 Stappenbeck, Geol. Aufb. d. Vorkordillere (Geol. u. Palaeont. Abh. N. F., Bd. IX,
Heft 5, 1911), pp. 31-32.

33 Nikitin, Mem. Com. G60I. Russ., vol. V, no. 5, 1890, pp. 66, 165, t. Ill, Figs. 1 to 3.

34 De Verneuil, Geol. Russ. II, Palaeont., p. 165, t. VI, Fig. 2. v-

33 Hayasaka, op. cit., 1922, p. 125, PI. VI, Figs. 10 to 13.

36 Mansuy, Mem. Serv. Geol. Indo-Chine, vol. 2, fasc. 4, 1913, p. 66, PI. VI, Fig. 4.

136 GEOLOGICAL COMPARISON OF SOUTH AMERICA WITH SOUTH AFRICA

Gortani37 would regard Sp. fritschi Schellw. as only a variety of Sp. supra-
mosquensis , and there are many closely allied species from the upper Carbon¬
iferous of Russia, such as Sp. ussensis Stuck.,38 which are difficult to separate.

Spirifer mexicanus Shumard var. nov. neotropica (Plate XIV, Figs. 3, 4)

There are two specimens (7325, 7366) of a species of Spirifer belonging
to the Sp. mexicanus group which much resemble the varieties of Sp.
mexicanus from Texas, figured by Girty,39 and are distinguished by the
more definitely demarcated but smooth channel in the median sinus of the
pedicle- valve. This median channel in the sinus of one of our specimens
is deep, narrow, devoid of ribs, and preserves an almost uniform width,
but in the other (7366) is more open. The shell is longer, more oval, and
narrower in shape than Sp. supramosquensis , being longer than wide, with
a shorter hinge-line and smaller beak. The interior of part of the valve is
seen in one specimen and shows rather coarse pitting toward the lateral
margins on each side of the large median muscular area. There are seven
to ten low, rounded, flattened, simple ribs of subequal size on each lateral
lobe, and on the rounded slopes of the sinus there are three or four nar¬
rower equal similar ribs, and on the upper edge two much sharper ones.
The cardinal ribs are very faint. Very fine radial lines and delicate con¬
centric striation ornament the whole surface of the shell.

Dimensions — Length, c. 25 mm.; width, c. 30 mm.

Remarks — In spite of its more quadrate shape and simple ribs it seems
probable that this shell is more allied to Sp. mexicanus than to Sp. nikitini
Tschern.,40 but it is certainly a new variety.

Spirifer wynnei Waagen var. nov. argentina (Plate XIV, Figs, ya, 7 b)

Shell transversely subelliptical, about twice as wide as long; hinge-line
less than width of shell; cardinal angles rounded. Pedicle- valve convex,
deeper than opposite valve; beak prominent, moderately high, somewhat
incurved; hinge-area triangular, gently concave, inclined steeply to plane
of valve, well-defined from lateral lobes by sharp edges; surface of valve
crossed by shallow, broad, rounded median sinus, not sharply marked off
from lateral lobes, increasing in width and depth anteriorly, with floor pro¬
duced with broad, rounded, projecting tongue arching steeply upward, so
as to be nearly at right angles to plane of valve; lateral lobes rounded, gently
to strongly convex from side to side. Sinus holding nine to ten subequal,
narrow, low, rounded ribs, which mostly divide at about half their length,
making fifteen to eighteen on the anterior margin. Lateral lobes with ten to
•twelve similar, rather larger ribs, which bifurcate once at about half their
length and sometimes again nearer margin, or rarely trifurcate, giving an
appearance of fasciculation and numbering twenty-four to twenty-eight of
subequal size on the margin, those near the cardinal edge becoming smaller
and fainter. Brachial valve less convex and shallower than pedicle- valve,
with low, broad, rounded median fold increasing in width anteriorly, not
marked off from lateral lobes; beak small, slightly elevated, scarcely
incurved; hinge-area narrow, with sharply defined edges, lying in plane of
valve. Fold with five to seven narrow, low, rounded ribs, arising from the
beak, and each bifurcating at about one-third to one-half its length, and

37 Gortani, Palseont. Ital., vol. XII, 1906, p. 26, t. II, Figs. 15 to 18.

38 Stuckenberg, Mem. Com. G60I. Russ., n.s., Liv. 23, 1905, pp. 44, 123, t. Ill, Fig. 17;
t. V, Figs. 3 and 4; t. VII, Fig. 11.

39 Girty, Prof. Paper 58, U. S. Geol. Surv., 1908, p. 360, PI. XIII, Figs. 1 to 9.

40 Tschemyschew, op. cit., p. 542, t. XIII, Fig. 2.

UPPER CARBONIFEROUS FOSSILS FROM ARGENTINA

137

•some dividing a second time so as to form sixteen to eighteen ribs on the
front margin. Lateral lobes with five to six similar but rather larger ribs on
each side, which bifurcate soon after their origin and mostly again at about
half their length or near the margin, so as to make about twenty to twenty-
four in all on the margin, with a decided tendency to fasciculation. In both
valves the ribs on the fold and in the sinus tend to be smaller than those
on the lateral lobes.

Dimensions — (7309): Length of brachial valve, 31 mm.; width of bra¬
chial valve, 50 to 54 mm. ; depth of conjoint valves, 26 mm.

Remarks — This form, which is represented by five imperfect specimens
in different states of preservation, is undoubtedly closely allied to Sp.
wynnei Waagen,41 but it can hardly be considered identical with the Salt
Range type-examples, though it may be regarded as a variety. The chief
differences are in the tendency to fasciculation of the ribs and in the fact
that they are smaller on the fold and sinus than on the lateral lobes. The
rounded character and low elevation of the fold on the brachial valve and
the sharply demarcated hinge-area on the pedicle-valve are features which
distinguish it from another Salt Range species, Sp. oldhamianus Waag. ;42
the number of ribs is also less. The lower Carboniferous species Sp. crassus
De Kon.43 is perhaps allied to our shell, but it has a less marked median fold
and sinus, and no tendency to fasciculation of the ribs. Some of the shells
which from time to time have been referred to Sp. striatus Mart, show
a marked resemblance in the ribbing, but differ by not possessing rounded
cardinal angles, which is also one of the chief distinctions of our shell from
the true Sp. cameratus Morton, though Derby44 attributed some Brazilian
shells of this shape to this species. The fine-ribbed specimens from the British
lower Carboniferous which Davidson45 at first referred to Sp. duplicicosta
Phill. but subsequently46 transferred to Sp. striatus are almost inseparable
from our shells, but the present author does not agree with Davidson’s views
-about the species. Sp. volgensis Stuck.47 from the Russian upper Carbonif¬
erous may also be compared. Diener48 has figured and described examples
of Sp. wynnei from Chitichun, which much resemble our specimen. The
species which Nikitin49 described from the Gshelian of Russia as Sp. post-
striatus was referred in 1889 by Tschemyschew to Sp. wynnei (but subse¬
quently in 1902 to Sp. cameratus ) ; it differs from our shell by having a more
triangular shape and longer hinge-area, the latter extending to the cardinal
-angles instead of being considerably less than the width of the shell. The
ribbing, however, of Sp. poststriatus is more like that of our shell than is that
of Sp. wynnei , being subfasciculate. Undoubtedly our shell belongs to the
same group as that containing Sp. striatus , Sp. duplicicosta , Sp. cameratus ,
Sp. condor , Sp. fasciger, Sp. ravana, and Sp. marcoui , all of which are
recorded by Tschemyschew50 from the upper Carboniferous of Russia.
Hayasaka,51 who describes Sp. wynnei from the upper Carboniferous of

41 Waagen, Salt Range Foss., I, p. 517, PI. XLIV, Figs. 6 and 7

42 Ibid., I, p.518, Pl.XLVI.

43 De Koninck, Faune Calc. Belg., VI (Ann. Mus. R. Belg., XIV, 1887), p. 137,
PI. XXIII, Figs. 3 to 9.

44 Derby, Bull. Cornell Univ., 1874, p. 12, PI. I, Fig. 9 (non cet.).

45 Davidson, Mon. Brit. Foss., Brach. II, p. 21, PI. Ill, Figs. 7 to 9.

*6Ibid., p. 221.

47 Stuckenberg, Mem. Com. Geol. Russ, n.s., Livr. 23, 1905, pp. 40, 122, t. Ill, Fig. 19.

48 Diener, Himal. Foss., vol. 1, pt. 3 (Palaeont. Ind. Ser. XV.) 1897, p. 44, PI. VII,
Figs. 1 to 4.

49 Nikitin, op. cit., 1890, pp. 64, 164, t. II, Figs. 16 to 19.

50 Tschemyschew, op. cit., 1902, pp. 133-146.

61 Hayasaka, op. cit., 1922, p. 'I27, PI. VI, Figs. 15 and 16.

138 GEOLOGICAL COMPARISON OP SOUTH AMERICA WITH SOUTH AFRICA

Manchuria, notes points of resemblance between it and Sp. volgensis Stuck.
It is said also to occur in the “lower Permian” of Australia, according to
Freeh, and in the upper Carboniferous of California, and Schellwien52-
figures it from the Trogkofel beds of the C-arnic Alps.

Spirifer saltensis sp. nov. (Plate XIV, Figs. 8a, 8b)

Shell transversely elliptical, much compressed; cardinal angles strongly
rounded; cardinal line less than width of shell. Pedicle- valve gently convex,
most so posteriorly; beak small, pointed, elevated, incurved, with concave
shoulders; hinge area small, triangular, nearly in plane of valves, with
sharply defined edges. Surface of valve with weak, broad, shallow, but
well-defined, rounded sinus holding four to five narrow, low, rounded,
simple, equal ribs; lateral lobes covered with eight to nine much broader,
low, rounded, flattened ribs, becoming narrower toward the cardinal angles,
and each dividing near the margin into two, or usually three, much smaller
ribs, giving a subfasciculate appearance. Brachial valve less convex than
pedicle-valve, with a low, scarcely raised, but definite broad median fold,
increasing rather rapidly in width and carrying a median weak, narrow,
simple rib, and on each side of it a stronger but narrow, rounded, bifurcated
rib, the division taking place at about the third of its length; lateral lobes
with six to seven much broader, low, flattened ribs dividing into three
smaller ones near the margin, and clearly forming fascicles; toward the
cardinal margin all the ribs become very weak and faint.

Dimensions — (7296) : Length, 20 mm. ; width, 29 mm. ; thickness, 10 mm.

Remarks — The relations of this shell, of which there is only one speci¬
men which is fortunately nearly perfect, are undoubtedly with the earner a-
tus group of species; the fasciculation of the ribs is a distinctive feature.
The rounded elliptical shape of the shell and short hinge-line are unlike
Sp. fasciger or its allies, although the ribbing especially recalls some forms
attributed to Sp. musakheylensis Dav.,63 which is often regarded as only a
variety of Sp. fasciger.5* But the elliptical shape, rounded cardinal angles,
and short hinge-line are found combined with a similar division and sub-
fasciculation of the ribs in some shells referred by Davidson 55 to Sp. dupli -
cicosta Phill. from the British lower Carboniferous, and to Sp. cameratus
Morton from Brazil,56 of which species our shell might even be considered
a variety.

Spirifer barrealensis sp. nov. (Plate XIV, Fig. 2)

Shell transversely subtriangular. Pedicle-valve convex, with deep, well-
defined median, subangular sinus, increasing slowly in width to front margin ;
hinge-line long, equal to width of valve; cardinal angles acute; beak high,
prominent, acutely pointed, incurved; hinge-area high, triangular, concave,
nearly in plane of valve. Surface of shell marked with five to six low, rounded,
simple, weak ribs on each lateral lobe, becoming fainter and almost obsolete
toward the cardinal angles ; sinus with lateral slopes bearing a faint, low
narrower rib on each side, arising at about half the length of the valve by the
unequal division of the larger rib forming the edge of the sinus, the floor of

62 Schellwien, Fauna d. Trogkofelsch., Abh. k. k. geol. Reichsanst., XVI, 1900, p. 75,
t. X, Figs. 5 and 6.

63 Diener, Himal. Foss., vol. I, pt. 4, p. 35, PI. Ill, Figs. 3 and 4; PI. IV, Figs. I and
2; PI. V, Fig. 1.

64 Reed, Upper Carb. Foss. Chitral, Palaeont. Ind., n.s., vol. VI, mem. 4, 1925, p. 42
and references.

65 Davidson, op. cit., PI. II, Fig. 11 (non cet.).

66 Derby, op. cit., p. 12, PI. I, Figs. 3, 14 (non cet.).

UPPER CARBONIFEROUS FOSSILS FROM ARGENTINA

139

the sinus being narrow, concave, and the width of a rib. Whole surface of
valve covered with closely placed concentric lamellose striae and growth¬
lines, and with very delicate radial striae. Brachial valve unknown.

Dimensions — (7371): Length, c. 17.5 mm.; width, c. 32.0 mm.

Remarks — The affinities of this species seem to be with Sp. aff. boon -
ensis Swallow, described by Girty57 from Oklahoma. The one specimen in
the present collection is crushed and imperfect, only the central portion
and left lateral lobe of the pedicle-valve being preserved. Sp. keilhavii
Von Buch58 from the upper Carboniferous of the Urals, etc., is less like it.

Spirifer aff. rajah Salter (Plate XIV, Fig. 5)

There is one imperfect specimen (7317) of a pedicle-valve of a species of
Spirifer which may be a variety of Sp. barrealensis, but it differs in being
subquadrate in shape, in possessing more numerous and narrower ribs on
the lateral folds, and by having on the steeply inclined, flattened slopes of
the sinus two to three very faint and narrower ribs ; the floor of the sinus
is flattened, of nearly uniform width, and rather wider than one of the
inner ribs on the lateral lobes, just as in Sp. barrealensis. The minute
ornamentation is identical. In our specimen the anterior part of the shell
is sharply bent under the posterior part, but the sinus, with its short pro¬
jecting tongue, and the concentric lamellae near the edge, are well pre¬
served, and it is in this region that the ribbing is most clearly shown. The
cardinal angles are obtusely angular, and the shell much resembles certain
of the specimens figured by Broili59 from Timor, which he refers to the
Himalayan species Sp. rajah Salter. Sp. samarensis Stuck, is also allied.

Spirifer ( Martinia ) cf. simensis Tschernyschew (Plate XIV, Fig. 6)

There are two specimens of pedicle- valves in the collection (7338, 7363)
which seem comparable to, if not identical with, the shell figured and
described by Tschernyschew60 from the Schwagerina horizon in the Urals
under the name Martinia simensis. Mansuy61 has recorded this species
from Tonkin.

Dimensions — (7363) : Length, c. 15 mm.; width, c. 15 mm.

Spirifer ( Martiniopsis ) cf. aschensis Tschernyschew

An imperfect pedicle- valve (7361) which shows the umbo, the median
channel-like sinus, and the faint ribs on the lateral lobes, may be compared
with Tschernyschew’ s Martiniopsis aschensis 62 rather than with any of the
other closely allied species of the same subgenus described by the same
author from the Schwagerina horizon in Russia.

Spiriferina zewanensis Diener (Plate XIII, Fig. 3)

There is one nearly perfect but somewhat compressed specimen (7312) of
a species of Spiriferina having the pedicle- valve in a good state of preserva¬
tion and not crushed ; the brachial valve is somewhat flattened by pressure,
but it shows all essential characters, and the ornamentation of the surface

67 Girty, Bull. 544, U. S. Geol. Surv., 1915, p. 91, PI. XI, Fig. 5.

68 Tschernyschew, op. cit., p. 527, t. XL, Figs. 1 to 4.

69 Broili, Palasont. Timor, VII, No. 12, 1916, p. 34, t. CXIX, Figs. 1 to 11, t. CXX,
Figs. 1 to 6.

60 Tschernyschew, op. cit., p. 569, t. L, Figs. 1 to 3.

61 Mansuy, op. cit., vol. V, fasc. 4, 1916, p. 33, PL V, Fig. 10.

62 Tschernyschew, op. cit., p. 557, t. L, Fig. 4.

140 GEOLOGICAL COMPARISON OF SOUTH AMERICA WITH SOUTH AFRICA

of both valves is beautifully preserved. In the pedicle-valve there are four
(and a weaker fifth) strong angular folds on each side of the median sinus,
which is broad, subangular, and rather rapidly increases in width anteriorly ;
the pair of folds bordering it are the strongest of the series, the others suc¬
cessively decreasing in size toward the cardinal region, a smooth triangular
space devoid of ribs being left along the cardinal line. The beak is small,
acute, elevated and slightly incurved, but not high, and the hinge-area is
low and narrow. The brachial valve has a narrow, prominent median fold,
rounded rather than subangular and very slowly increasing in width anteri¬
orly ; there are only three strong subangular folds on each side and traces of
a fourth one. The cardinal angles of both valves are broken off, but seem to
have been acute or subacute. The surface of both valves is covered with a
series of strong, equidistant, regular, thick imbricating lamellae about twenty
to twenty-five in number, and the shell substance is coarsely punctate. A
very delicate radial striation is also visible with a lens on the surface.

Dimensions — Length, 14 mm.; width (estim.), 28 mm.

Remarks — This shell is much like Sp. octoplicata Sow. as redefined
by North, especially the mut. 8 Vaughan,63 but the species from the Zewan
beds of Kashmir which Diener64 first described as Sp. cf. kentuckiensis
Shum., but subsequently as Sp. zewanensis sp. nov., seems to be indistin¬
guishable from our specimen.

Reticularia notica sp. nov. (PI. XIII, Figs. 8a, 8b, 10)

Shell subcircular. Pedicle valve moderately convex; beak high, promi¬
nent, pointed, incurved, with umbonal slopes hollow; cardinal area concave,
triangular, steeply inclined; hinge-line short, about half width of shell. Sur¬
face of valve marked with continuous median shallow sinus, scarcely increas¬
ing in width anteriorly. Ornamentation of shell consisting of numerous
closely placed subequidistant concentric thin lamellae with their edges pro¬
vided with minute equidistant, rather widely spaced, small, short, simple,
recumbent spines, not crossing the lamellae but forming narrow fringes.
Brachial valve unknown.

Dimensions — Length, 15 to 16 mm.; width, 14 to 15 mm.

Remarks — This species, of which there is one broken example (7326) of
a pedicle valve having the surface beautifully preserved and showing the
ornamentation, and three other decorticated and poor specimens (7376,
7345, 7372) can not be referred to Ret. lineata Mart., because of the median
sinus and the character of the marginal spinose fringes. But as often remarked,
R. lineata has been made to include a variety of forms. It is more like Ret .
setigera Hall and Whitfield 65 in the ornamentation and in the median sinus
and shape we may also compare R. orientalis Mansuy,66 and Ret. rostrata
Kut.67 R. waageni Loczy,68 from southern China and especially Squamularia
guadelupensis Shum.69 from Texas, may also be compared.

63 North, Quart. Journ. Geol. Soc., vol. LXXVI, pt. 2, 1920, p. 217, PI. XIII, Fig. 9.

64 Diener, Himal. Foss., vol. I, pt. 2, 1899, p. 61, PI. V, Figs. 11 and 12; id. Anthrac.
Foss. Kashmir, etc. (Palasont. Ind., vol. VI, mem. 2, 1915), p. 90, PI. IX, Fig. 12.

65 Hall and Whitfield, Explor. 40th Parallel, p. 270, PI. VI, Figs. 17 and 18.

66 Mansuy, op. oil., vol. II, fasc. 4, p. 81, PI. IX, Fig. 2.

67 Tschernyschew, op. cit., p. 575, t. XX, Figs. 14 to 18.

68 Loczy, Beschr. Wiss. Ergeb. Pal. Stratigr. Result. Reise des Grafen Bela Szechenyi.
(Budapest, 1898), p. no, t. IV, Figs. 1 and 2.

69Girty, op. cit., 1908, pp. 367 to 369, PI. XIV, Figs. 2 and 3.

UPPER CARBONIFEROUS FOSSILS FROM ARGENTINA

141

Ambocoelia plano-convexa Shumard

This well-known brachiopod, which occurs in the upper Carboniferous
of America,70 Asia,71 and Europe72 and was recorded by Derby73 from the
coal measures of Brazil and by Kozlowski74 from the upper Carboniferous of
Bolivia, is represented by one pedicle-valve in the collection, measuring
about 7.5 mm. in width and about 5 mm. in length.

Athyris ( Spirigerella ) ? sp.

There is one fragmentary specimen of a broadly subcircular pedicle-
valve with a weak anterior, broad, median sinus, and strong concentric
growth-ridges which seems to belong to some species of Athyris or Seminula
and may perhaps be compared with Spirigerella grandis Waag.75 and the
allied species from the Productus limestones. We may also compare some of
the shells from the upper Carboniferous of Bolivia figured by Kozlowski76
under the name Seminula argentea (Shepard) , for the genus of our specimen
is uncertain.

Hemiptychina cf. sublx vis Waagen (Plate XIII, Fig. 5)

A small oval terebratuloid shell (7300 showing only the pedicle- valve
has the external appearance and shape of Hemiptychina sublcevis Waag.,77
but its identification is somewhat uncertain. It measures about 6.5 mm.
in length.

Pseudamusium stappenbecki sp. nov. (Plate XIII, Figs. 11 and 13)

Shell obliquely subelliptical, longer than high, transverse, bilaterally
asymmetrical, having an oblique axis and anterior swing; gently biconvex,
compressed. Right valve with body gently convex, more or less flattened;
beak pointed, with its edges meeting at a right angle or more than a right
angle, situated excentrally at about one-third the length of the valve from
posterior end; anterior end of valve rounded, projecting in front, strongly
arched forward above, curving back sharply below into inferior margin, which
makes a wider, gentler curve and passes obliquely up into shorter, more
semicircular posterior margin; junction of body above with posterior ear
straight ; junction of body with anterior ear slightly concave. Anterior ear
large, narrow, long, acutely triangular, depressed, sharply marked off from
body, rounded in front, without byssal slit; surface marked with four to five
broad, low radial folds. Posterior ear small, short, depressed, smooth, weakly
but distinctly marked off from body, with obtuse posterior angle, higher
than long, extending a short distance down posterior margin of body.
Surface of body marked with very faint, low, wide, flattened radial ribs
of subsequal size, separated by incised lines and only distinct toward the
margins; a few closely placed fine raised radial lines are present on anterior
and posterior upper margins of body near junctions with ears; strong con¬
centric stride and growth-ridges at unequal distances apart cover the whole
surface of both valves. Left valve similar to right valve, but with the fine
radial lines extending over more of the surface of the body.

Dimensions — Length (oblique), 25 mm.; height, 22 mm.

70 Girty, Bull. 544 U. S. Geol. Surv. 1915, p. 94 and refs.

71 Mansuy, op. cit., vol. II, fasc. 4, 1913, p. 82, PI. IX, Fig. 4.

72 Tschemyschew, op. cit., p. 575, t. XX, Fig. 1.

73 Derby, Bull. Cornell Univ., 1874, p. 19, PI. VIII, Figs. 12, 16, 18, PI. IX, Fig. 7.

74 Kozlowski, op. cit., 1914, p. 76, Text-Fig. 19, PI. I, Fig. 5, PI. X, Figs. 1 to 14.

75 Waagen, op. cit., p. 461, PI. XXVI, Figs. 1 to 7 (especially Figs. 3 and 4).

76 Kozlowski, op. cit., 1914, p. 79, PI. XI, Figs. 1 to 46.

77 Waagen, op. cit., p. 364, PI. XXVII, Figs. 1 to 3; Diener, Palasont. Ind., ser. XV,
Vol. I, PI. V, 1903, p. 40, PI. II, Figs. 3 a to d.

142 GEOLOGICAL COMPARISON OF SOUTH AMERICA WITH SOUTH AFRICA

Remarks — This species is represented by several fairly perfect speci¬
mens, but the radial ribbing is only seen in those having the shell more or
less preserved, most of the specimens being casts in which the concentric
lines and ridges are more conspicuous.

The right valves (7287, 7290, 7303) are more complete than any of the
left valves (7301?, 7302, 7291, 7289, 7284), but there seems to be little or no
difference in their characters. The generic reference of this shell is to
Pseudamusium as defined by Wheelton Hind, and it seems allied especially
to Ps. anisotum Phill.78 and to Pecten sibiricus De Vern.,79 which Hind con¬
siders to be probably identical.

Diener80 has figured an unnamed species of t( Aviculo pecten” from the
Zewan beds which seems rather to resemble the Argentine shell. The well-
known Russian species Av. sericeus De Vern.81 is less oblique and less trans¬
verse, and the same differences are noticeable in the Amazonian upper
Carboniferous shell which Katzer82 has figured as Euchondria neglecta
Geinitz. But Herrick’s species Crenipecten foerstiizz of the Pottsville fauna
closely resembles our species in character.

Pseudamusium cf. ellipticum (Phillips) (Plate XIII, Fig. 12)

There seems to be another species of Pseudamusium in the collection
which is only represented by one good example of a left valve (7304), and
it differs from the foregoing in its shape and apparently in its ornamenta¬
tion. It is not oblique and is higher than long, being a bilaterally symmetri¬
cal oval shell like a Pecten; the sides of the beak which is central in position,
meet at about 750; the anterior ear is shorter broader, and more equilater-
ally triangular than in Ps. stappenbecki and shows concentric lines instead of
radial ribs. The long, straight shoulders of the body descend nearly to the
middle of the valve. The surface is gently convex, and though the shell is
mostly missing, there is a regular fine radial lineation visible over the whole
surface, passing into broad, flattened ribs near the margins, which are more
distinct than in the previous species, and the concentric ridges and striae
are less well developed.

This shell seems to resemble Ps.fibrillosum (Salt.) of the Coal Measures
of England, as described by Wheelton Hind,84 but still more Ps. ellipticum
Phill.85 of the Carboniferous limestone of Great Britain and Ireland.

Dimensions — (7304) : Height, 25 mm.; length, 19 mm.

Pseudamusium cf. fibrillosum (Salter)

There is one left valve (7324) of a species of Pseudamusium which seems
more like Ps. fibrillosum (Salt.)85 as described by Wheelton Hind than
Ps. anisotum, Ps. ellipticum, or Ps. redesdalense Wh. Hind. It has the up¬
right oval shape and vertical axis of Ps. ellipticum and Ps. fibrillosum, but
the finer ornamentation of the latter without any wide, flat ribs.

Aviculopecten barrealensis sp. nov. (Plate XIII, Fig. 14)

Shell obliquely oval, gently convex. Body subtriangular, rounded;
beak subanterior, small, with sides meeting at about 90°. Anterior margin
of shell short, strongly arched, sweeping down and back obliquely into well-

78 Wheelton Hind, Brit. Carb. Lamellibr., vol. II, 1903, p. 104, PI. XXI, Figs. 13 to 20.

79 De Verneuil, Geol. Russ., II, Palaeont., p. 329, PI. XXI. Fig. 7.

80 Diener, Himal. Foss., vol. I, pt. 2, 1899 (Palseont. Ind.), p. 16, PI. I, Fig. 3.

81 Stuckenberg, Mem. Com. Geol. Russ., vol. XVI, no. 1, 1898, p. 200, t. I, Fig. 22.

82 Katzer, Grundziige d. Geol. d. unter. Amazonasgebietes (Leipzig, 1903), p. 185,
t. VIII, Fig. 6.

83 Morningstar, Geol. Surv. Ohio, Ser. 4, Bull. 25, 1922, p. 230, PI. XIII, Figs. 7, 8.

84 Wheelton Hind, op. cit., p. 106, PI. XVI, Figs. 16 to 22.

85 Ibid., p. 103, PI. XX, Figs n to 18.

UPPER CARBONIFEROUS FOSSILS FROM ARGENTINA

143

arched inferior margin which curves up sharply behind with short rounded
projecting posterior end. Ears well marked off from body, flattened
depressed; anterior ear rather large, triangular, projecting, with rounded
anterior margin ; [posterior ear larger ( ?) , triangular, with acute ( ?) posterior
angle]. Surface of valve covered with fine, regular, straight, mostly equi¬
distant, threadlike, raised radiating ribs, of equal strength, thirty to thirty-
three in number, less than half being primary and continuous from beak to
margin, the rest arising by intercalation mostly at about one-fourth the
length of the others; interspaces wide, flat, all of them as well as the ribs
being crossed by rather closer, finer, regular, threadlike raised lines which
are equidistant in the lower half of the shell, but become more and more
crowded and numerous toward the beak. Anterior ear with concentric
growth-lines.

Dimensions — (7362): Length (oblique), 11.5 mm.; height, 9.0 mm.

Remarks — Only one specimen (7362) occurs in the collection, but it is
a nearly perfect left valve. The surface of this shell is divided up into
numerous oblong cancellce by the crossing of the radial and concentric
lines, as in A.forbesii McCoy,86 which it also much resembles in shape, but
this Argentine species differs by the ribs being of equal strength, and the
obliquity of the shell is more marked and the body narrower and not subor-
bicular. Ps. radialis (Phill.) as figured by Waagen87 from the Salt Range
has a somewhat similar ornamentation.

Nuculana ( Leda ) cf. bellistriata Stevens (Plate XIII, Fig. 7)

One small right valve of a species of Nuculana occurs in the collection
(7339)* but it is only an internal cast and does not show the dentition. It
seems somewhat like N. bellistriata Stevens,88 from the Pennsylvanian of
the United States, but is shorter and blunter behind. Probably it is a
new species.

Dimensions — Length, 10 mm.; height, 7 mm.

Euomphalus subcircutaris Mansuy (Plate XV, Figs. 1,2,4)

There is a species of Euomphalus rather abundantly represented in the
collection and including several well-preserved specimens which seems
absolutely indistinguishable from Mansuy’s E. subcircularis 89 from the
Carboniferous of Chouei Tang, Yunnan. Apparently this is the shell which
Stappenbeck mentions from Barreal as resembling E. parvus Waag.,90 but
as being much larger.

The specimens average about 25 to 30 mm. in diameter, and some
of them (7322) are well preserved and show both the apical and basal sur¬
faces. In all respects they agree with Mansuy’s figures and description,
which need not be repeated.

Pleurotomaria ad vena sp. nov. (Plate XV, Fig. 5)

Shell low, conical, heliciform, height and diameter being about equal,
basal whorl occupying about half the height; apical angle about 130°;
whorls rounded, five to six in number, rapidly decreasing in size to apex.
Basal whorl large, rounded below, more or less flattened above, rising at
an angle of 450 to 6o° from the periphery, which is obtuse; slit-band promi-

86 Wheelton Hind, op. cit., p. 83, PI. XVIII, Figs. 3 to 7.

87 Waagen, op. cit., p. 280, PI. XXIII, Fig. 5.

88 Girty, Bull. 544, U. S.Geol. Surv., 1915, p. 122, PI. XIV, Figs. 1 to 9; Jakowlew,
Mem. Com. Geol. Russ., n.s., Livr. 4, 1903, p. 10.

89 Mansuy, op. cit., vol. I, fasc. 2, 1912, p. 105, PI. XIX, Figs. 3a to d.

90 Waagen, op. cit., p. 89, pi. IX, Fig. 2.

144 GEOLOGICAL COMPARISON OF SOUTH AMERICA WITH SOUTH AFRICA

nent, situated slightly above the periphery, narrow, concave, deep, with
sharp raised edges. Upper whorls rounded. Sutures not deeply sunken,
with slit-band on upper whorls situated on or slightly above them. Base of
shell convex, rounded; umbilicus small, closed, depressed; lip of mouth
somewhat thickened. Shell ornamented with revolving liras crossed by finer
spiral lines which at their intersection form small pustules or nodules giving
a moniliform character to the lirae; on apical surface of each whorl above the
slit-band there are five to seven of such equidistant revolving liras of equal
strength, closely nodulated, mostly with finer, similarly nodulated liras
between them; below the slit-band on the basal whorl are more numerous
and more closely placed finer nodulated liras, with the closely placed spiral
lines bending back to meet the slit-band at an angle of about 20°.

Dimensions — Height, c. 30 mm. ; basal diameter, c. 35 mm.

Remarks — There is one specimen (7355) somewhat crushed but showing-
well the basal whorl, slit-band, and ornamentation. Another (7360) shows
the spire and upper whorls better. The species seems to be allied to PL
punjabica Waag.91 of the upper Productus limestone of the Salt Range,
but differs in the upper whorls being more rounded, in the slit-band being
sutural, and in the more marked nodulation of the revolving liras. We may
perhaps also compare PI. timorensis Wanner92 from the Permo-Carbonifer¬
ous of Timor and Ptychomphalus venustus Mansuy93 from the correspond¬
ing beds of Indo-China, especially with regard to the shape of the shell and
its ornamentation.

Pleurotomaria argentina sp. nov. (Plate XV, Figs. 3a, 3 b, 3c)

Shell conical, subtrochiform ; apical angle 750; whorls five to six in
number, bluntly angulated at periphery, slowly decreasing in size. Basal
whorl large, fully half the total height of the shell, with swollen, convex
rounded base, subangular periphery bearing a prominent, well-defined,
sunken, narrow slit-band having sharply raised edges, and with a somewhat
flattened apical face sloping up to suture-line. Upper whorls with promi¬
nent suture-band situated a little distance above suture-line, which is not
sunken. Surface of whorls marked with regular revolving lirae, numbering
six to seven on apical face, equidistant and bearing regular sharp, equi¬
distant, small spinose tubercles; below the slit-band on the upper whorls
are one to three similar lirae. Lower surface of basal whorl with several
similar equidistant lirae immediately below slit-band, but nearer umbilicus
they become finer and less distinct or obsolete, fine spiral growth-lines
being here specially developed. Umbilicus sunken, closed. Mouth large,
subcircular.

Dimensions — (7334) : Height, c. 27 mm.; diameter, c. 24 mm.

Remarks - — This species is closely allied to PI. ( Phanerotrema ) gray -
villensis Norvv. and Pratt, as described by Girty 94 from the Pennsylvanian of
Oklahoma, differing chiefly in the absence of strong spiral lines crossing the
revolving lirae, and of the transverse ridges below the suture-lines on the
apical surface of the whorls.

Pleurotomaria barrealensis sp. nov. (Plate XVI, Figs. in, 16)

Shell subturbinate, composed of four to five rounded whorls, rather
rapidly decreasing in size to apex; apical angle about 8o°. Basal whorl

91 Waagen, op. cit., p. 115, PI. XI, Figs. 3 and 4.

92 Wanner, Palaeont. Timor, Lief. XI, Abh. XVIII, 1922, p. 20, t. 151, Figs. 9 a and 6.

93 Mansuy, op. cit., vol. II, fasc. 4, 1913, p. 102, PI. XI, Fig. 3.

94 Girty, Bull. 544 U. S. Geol. Surv., 1915, p. 149, PI. XXIII, Figs. 2 to 8.

UPPER CARBONIFEROUS FOSSILS FROM ARGENTINA

145

large, rounded-subquadrate in section, being somewhat flattened on outer
face; slit-band narrow, inconspicuous, situated at junction of outer face
with convex apical face; inferior surface of basal whorl rounded, but not
strongly convex, somewhat flattened; umbilicus sunken, small; mouth
transversely oval, wider than high, with thickened inner lip. Upper whorls
with more or less flattened vertical outer face below the slit-band, which is
situated in about the middle of each whorl. Inferior surface of basal whorl
crossed by strong subequidistant, sublamellose, spiral growth-lines and by
numerous rather closely placed, subequidistant, thick, thread-like, smooth
revolving liras, not tuberculated; outer face of basal whorl ornamented with
similar more widely spaced revolving liras; apical face (not well preserved)
ornamented with similar revolving liras.

Dimensions — Height, c. 55 mm.; diameter at base, c. 55 mm.

Remarks — There is only one specimen (7323) of this shell, but it is
nearly complete, though the surface ornamentation is destroyed, except on
the basal whorl, and the slit-band is nowhere distinct. We may compare this
species with PI. orientalis Roemer, as figured by Fliegel95 from the upper
Carboniferous of Padang, Sumatra, and with PL cf. punjabica Waag. as
figured by Diener 96 from the Productus shales of the Himalayas.

Metoptoma ? sp.

One much-crushed subcircular shell (7318) may possibly be referred to
the genus Metoptoma , for apparently it had a low capuliform shape with an
elevated submarginal apex scarcely overhanging the posterior margin. The
surface of the shell seems to have been gently convex, very obliquely coni¬
cal, and there are traces of twx> to three small, short marginal radial folds
in the median line on the anterior edge. On one part of the central pre-
umbonal region regular fine, equidistant, incised radial lines are visible, and
a few concentric growth-strias and ridges sweep around the margins and pass
beneath the umbo.

Dimensions — Diameter, 22 to 25 mm. ; height, + 4 mm.

Orthoceras sp.

One small fragment of a subcylindrical shell with a circular cross-section
is probably referable to a species of Orthoceras. The specimen is only 10.5
mm. in length and shows five to six horizontal septa in that distance. The
siphuncle is central and circular and measures one-sixth to one-seventh of
the diameter. The walls of the cameras seem to be unusually thick. The
external surface of the shell seems to be smooth, except for very delicate
concentric striae. The affinities of this fragment are not clearly determinable,
owing to the poorness of the specimen. Another fragment (7354) of appar¬
ently the same species consists of one broken, isolated camera; the septa
are seen to be deeply concave and the siphuncle apparently expands in the
upper part of each chamber. If the thickness of the walls of the chambers
as seen in the other specimen is due to a marginal infilling we may per¬
haps compare Pseudorthoceras knoxense Girty97 from the Pennsylvanian of
America, which also agrees in its slow rate of tapering, central siphuncle,
distance apart of the septa, and circular section. The rate of tapering,
central siphuncle, circular section, and distance apart of the septa in our
specimens also suggest a comparison with Orth, punjabiense Waag.98 from
the middle Productus limestone of Musakheyl.

95 Fliegel, Palaeontographica, Bd. XLVIII, Lief. 3, 1901, p. 113, t. VIII. Figs. 7 and 8.

96 Diener, Palaeont. Ind., ser. XV, Vol. I, pt. 5, 1903, p. 100, PI. V, Figs. 1 to 3.

97 Girty, Bull. 544 U. S. Geol. Surv.. p. 227, PI. XXVII, Figs. 1 to 6

98Waagen, op. cit p. 71, PI. VI. Fig. 11.

146 GEOLOGICAL COMPARISON OF SOUTH AMERICA WITH SOUTH AFRICA

COMPOSITION AND CORRELATION OF THE FAUNA

The following is a list of the species in the present collection
which have been identified and described above :

* Fenestella aft. perelegans Meek.

sp. ind.

Polypora aff. biseriata Ulr.

Orbiculoidea saltensis sp. nov.

*t Productus lineatus Waag.

* curvirostris Schellw. var. nov. barrealensis.

* cf. juresanensis Tschern.

* ( Marginifera ) cf. echinata Waag.

* ( Marginifera ) spinulo-co status Abich var. nov. peregrina.

*Chonetes cf. pseudovariolata Nik.

granulifer Owen.

*Camarophoria cf. mutabilis Tschern.

*Spirifer cf. supramosquensis Nik.

* wynnei Waag. var. nov. argentina.
saltensis sp. nov.

barrealensis sp. nov.

mexicanus Shum. var. nov. neotropica.

* aff. rajah Salt.

* (Martini a) cf. simensis Tschern.

* ( Martiniopsis ) cf. aschensis Tschern.

* Spiriferina zewanensis Diener.

Reticular ia notica sp. nov.

*\Ambocoelia plano-convexa Shum.

Athyris ( Spirigerella ) ? sp.

*Hemipty china cf. sublcevis Waag.

Pseudamusium stappenbecki sp. nov.

cf. ellipticum (Phill.).
cf. fibrillosum (Salt.).

Aviculopecten barrealensis sp. nov.

Nuculana ( Leda ) cf. bellistriata Stevens.

Euomphalus subcircularis Mansuy.

Pleurotomaria advena sp. nov.

argentina sp. nov.
barrealensis sp. nov.

Metoptoma ? sp.

Orthoceras sp.

With regard to the two horizons in the shales from which Doctor
Du Toit’s specimens were collected the following lists indicate the
distribution of the species :

Lower horizon (7281-7313).

Polypora aff. biseriata.

Fenestella sp. ind.

Productus cl. juresanensis.

Spirifer wynnei var. argentina.
saltensis.

Spiriferina zewanensis.

Hemipty china cf. sublcevis.

Pseudamusium stappenbecki.

cf. ellipticum.

UPPER CARBONIFEROUS FOSSILS FROM ARGENTINA

147

Upper horizon (7314-7376).

Fenestella aff . perelegans.

Orbiculoidea saltensis.

Productus lineatus.

curvirostris var. barrealensis.

( Marginifera ) cf. echinata.

( Marginifera ) spinulo-co status var. peregrina.

Chonetes cf. pseudovariolata.
granulifer Owen.

Camarophoria cf . mulabilis.

Spirifer cf. supramosquensis.
barrealensis.

mexicanus var. neotropica.

{Martinia) cf. simensis.

( Martinia ) cf. aschensis.

Reticularia notica.

Pseudamusium cf.fibrillosum.

Aviculopecten barrealensis.

Nuculana cf. bellistriata.

Euomphalus sub circular is.

Pleurotomaria advena.

argentina.

barrealensis.

Metoptoma ? sp.

Orthoceras sp.

The species marked with an asterisk (*) in the above list occur
either in the Carboniferous of Russia or parts of Asia, though several
are represented here by varieties. In many cases we have not been
able to feel sure that the other species are identical, owing to the
paucity or poor preservation of the specimens in the present col¬
lection, so that they can only be compared with already described
forms. A few are, however, identified without hesitation; such are
Productus lineatus , Chonetes granulifer, Amboccelia planoconvexa, Spiri-
jerina zewanensis, and Euomphalus sub circular is.

The species marked with a dagger (f) have been recorded by
previous geologists from South America, but these are very few, and
the remainder show little affinity. The fauna, in fact, of this Argen¬
tine locality is quite distinct from that of Brazil or Bolivia, and does
not show any striking resemblance to any occurring in North
America, except perhaps to the Guadelupian type.

Derby," in 1894, gave a list of the Amazonian upper Carbonifer¬
ous fauna, but without any figures or descriptions. Many had been
described in his earlier paper on the Brazilian Carboniferous fossils
from Itaituba. The most complete list of the upper Carboniferous
fossils from the Amazon region, with descriptions and figures of
several of the species, was given by Katzer,100 in 1903. Among the
species occurring in this area and the present collection from Barreal

99 Derby, Journal of Geology, vol. II, 1894, p. 480.

100 Katzer, Grundzuge d. Geol. d. unter Amazonasgebietes (Leipzig, 1903), pp. 142-
188, 263-268, t. IV-VIII.

148 GEOLOGICAL COMPARISON OF SOUTH AMERICA WITH SOUTH AFRICA

are: Productus lineatus and Amboccelia plano-convexa, while probably
some of the shells referred to Sp. condor by Katzer ( e.g ., op. cit., t.
V, Fig. i) should be identified with Sp. ef. supramosquensis , and Pr.
nebraskensis may be the same as the shell compared with Pr. juresa-
nensis. But the Amazonian fauna, which is a large one, consists
mainly of species not recognized at Barreal. Katzer (op. cit.,
pp. 246-253) has discussed the relations of this fauna with that of
other regions and has referred to the literature on the subject.

The relations of the Argentine fauna to that of the upper Car¬
boniferous of Bolivia, of which the brachiopods alone have been
adequately studied, is not close, as is seen by Kozlowski’s101 memoir.
But Amboccelia plano-convexa and Productus lineatus ( = cora (pars)
Kozl.) are species which the two faunas have in common.

Meyer,102 in 1914, described marine upper Carboniferous faunas
from Peru and Bolivia and discussed their occurrence generally in
South America, referring to Stappenbeck’s discovery of such at
Barreal, but without giving any further particulars. Of the Argen¬
tine species, Productus cora (including Pr. lineatus ) alone is men¬
tioned as occurring in Bolivia, but in Peru we note, in addition to this
species, Amboccelia plano-convexa. Reviewing the evidence, Meyer
assigns all the faunas to the upper Carboniferous and not to the
Permian. Douglas103 in 1914 briefly described a similar fauna of the
Titicaca district, ascribing it to the upper Carboniferous or Permo-
Carboniferous, and he recognized that a few forms were related
to “Permian” forms from the Salt Range. None of the Argentine
species appear to occur. In a subsequent paper104 he records the
occurrence of lower Carboniferous fossiliferous beds in southern
Peru, but the fauna is quite distinct from that of Barreal.

There is not any very close resemblance with the fauna of any
part of the Productus limestones of Asia, though a few species are
apparently identical and several are allied or comparable. Hayasaka,105
however, has described a small fauna of brachiopods from the
upper Carboniferous of the coal-bearing series of Hon-kei-ko,
Manchuria, which includes the following species occurring at
Barreal: Camarophoria cf. mutabilis, Spirifer supramosquensis , Sp.
wynnei, and some other allied species of Spirifer.

If we accept Holland’s correlation of the Productus limestones 106
we only find Spiriferina zewanensis of the Zewan beds as a Permian
form, though Pleurotomaria advena is more allied to an upper Produc-

101 Kozlowski, Brach. Carb. Super. Bolivie, Annales de Paleont. IX, 1914, pp. 1 to 100
Pis. I to XI.

102 Meyer, Neues Jahrb. f. Mineral, etc., Beil. Bd. XXXVII, 1914, pp. 590-651,
t XIII XIV

103 Douglas, Quart. Journ. Geol. Soc., vol. LXX, 1914, pp. 30-37, Pis. VIII, IX.

1MIbid., vol. LXXVI, 1920, p. 41.

105 Hayasaka, op. cit., 1922, pp. 1 17-137.

106 Holland, Mem. Geol. Surv. India, vol. LI, pt. 1, 1926, p. 22.

UPPER CARBONIFEROUS FOSSILS FROM ARGENTINA

149

tus limestone species than to any other. Productus lineatus and
Amboccelia planoconvexa, though occurring in the Zewan beds, are
abundant also on lower horizons and in the so-called upper Carbonif¬
erous of Russia and America. Chonetes granulifer is typically a
Pennsylvanian species ; and the species Sp. supramosquensis is char¬
acteristic of the Gshelian, which occurs immediately above the
Moscovian and is therefore well below the Permian. If we look at
the rest of the species from Barreal, we observe that nearly all are
closely allied to or comparable with established species from either
the lower Carboniferous of Europe or the middle or upper Car¬
boniferous of Russia or North America, and that none are limited
to undisputed Permian beds. Thus among the new forms, Spirifer
saltensis shows close affinities with some examples of Sp. duplicicosta
of the lower Carboniferous; Sp. barrealensis is especially allied
to Sp. boonensis; Reticularia notica is related to R. setigera of the
lower Carboniferous ; Pseudamusium stappenbecki has affinities with
upper Carboniferous species ; Pleurotomaria argentina closely resem¬
bles a species from the Pennsylvanian of the United States, and
PI. barrealensis is like an upper Carboniferous form from Sumatra.

Thus the weight of evidence from the fossils leads us without
hesitation to refer this fauna from Barreal to the Carboniferous , and
it seems that it should not be placed at the top of that formation, but
probably toward the base of the upper division. It is interesting to note
that Holland (op. cit.) places the glacial boulder bed of the Salt
Range in the Carboniferous, for the tillite of Barreal is stated to pass
up into and even include some of the beds from which the present
collection of fossils was obtained.

150 GEOLOGICAL COMPARISON OF SOUTH AMERICA WITH SOUTH AFRICA

TRIASSIC FOSSILS FROM RIO CLARO, PARANA, BRAZIL

The following species have been determined provisionally from the
material forwarded by Doctor Du Toit, but it is intended to publish full
descriptions and figures elsewhere at some later date. The fossils from
the upper zone have presented difficulties in their identification owing to
their occurrence in the form of casts.

Lower Horizon — Zone i :

Pachycardia aff. rugosa Hauer.

Anodontophora aff. trapezoidalis Mansuy.

Trigonodus aff. rablensis (Gredler).

Radiolaria (not determinable).

Upper Horizon — Zone 2:

P achy car dia neotropica sp. nov.

Myophoria ( Myophoriopis ) aff. carinata Bittn.

aff. lineata Miinst.

Megalodus ? neolropicus sp. nov. cf. triqueter (Wulf).

Gonodon ( Schafhautlia ) paranaense sp. nov.

Modiola aff. subcarinata Bittn.

Solenomorpha in the sense used by Holdhaus is not represented in the
collection, nor are there any species common to the two zones. Permian
forms are absent, the fossils from both horizons displaying undoubted
Triassic characters suggestive of the upper rather than the lower Trias.

INDEX

Authorities Cited in the Text

Aguirre, 19, 21

Arocena, 3, 4

Ave-Lallemant, 4 7, 48

Baker, C. L., 61, 83, 87, 89, 90, 92-93

Baker, H. A., 11, 26

Beder, 60, 77

Berry, 40, 55

Bodenbender, 28, 35~36, 38-39, 42-44,
46-47

Bonarelli, 56, 58, 98

Brackebusch, 43

Branner, 62-64, 7°, 93, 95-96

Brouwer, 114

Chamberlin, 65

Clarke, 11, 60-61, 100

Coleman, 23, 31, 67, 70-71, 74, 104

Crandall, 64-65, 94

Daly, 2

Derby, 61, 63-64, 94, 147
Douglas, 57, 148
Draper, 65, 67
Du Toit, 94, 101, 103, 1 19
Evans, 61
Ferraz, 59, 74
Fourmarier, 9
Gothan, 55
Gregory, 9
Groeber, 27, 51
Guillemain, 67, 73
Halle, 11-12
Harder, 65
Haug, 11
Hausen, H., 35
Hausen, J., 88, 90, 93
Hauthal, 19, 23
Heald, 55-57
Holdhaus, 81-82
Holland, 148-149
Huene, 79
Katzer, 147-148

Keidel, 14, 18-30, 32-35, 37, 42, 47, 49,
51,98
Knod, 97

Kozlowski, 97-98, 148

Kurtz, 36, 38-41, 89

Leme, 59, 61, 63-64, 82, 85, 89, 95

Lemoine, 10

Lisbda, 94

Lundqvist, 77

Mather, 55-57

Meyer, 148

Nagera, 5

Oliveira, 4, 67, 70, 72, 75, 81,83-84
Orbigny, 56, 62
Pacheco, 71, 76, 79, 83, 87
Pastore, 5

Penck, 36-38, 43, 35
Rassmuss, 51-52
Reed, 5, 35, 60, 82, 101
Rego, 83-84
Rimann, 53, 70
Rogers, 27
Schiller, 19, 20
Seward, 11-12, 40
Sobral, 4, 90
Solms-Laubach, 50
Soper, 95

Stappenbeck, 28, 32-33, 35, 38, 43, 47~49>

131

Stelzner, 47
Taylor, 1

Walther, 3-4, 62, 66-67, 69, 73, 76, 78,
82-84, 87, 90, 93
Wegener, 1, no, 115, 119
White, D., 77-78, 82, 96
White, I. C., 66, 72, 80, 83-84, 86
Windhausen, 27, 32, 51, 60, 103, 107-108
Woodworth, 70-74, 89, 92
Wright, 2
Zeiller, 77, 82

Fossils Described in Appendix

Ambocoelia plano-convexa, 141
Athyris, 14 1

Aviculopecten barrealensis, 142
Camarophoria cf . mutabilis, 135
Chonetes granulifer, 134

cf. pseudo variolata, 134
Euomphalus subcircularis, 143
Fenestella aff . perelegans, 13 1
Hemiptychina cf. sublaevis, 141
Metoptoma, 145
Nuculana, 143
Orbiculoidea saltensis, 132
Orthoceras, 145
Pleurotomaria advena, 143

argentina, 144
barrealensis, 144
Poly pora aff. biseriata, 132

Productus curvirostris, 133

cf. juresanensis, 133
lineatus, 133

(marginifera) cf. echinata, 133
spinulo-costatus,
134

Pseudamusium cf ellipticum, 142
cf. fibrillosum, 142
stappenbecki, 141
Reticularia notica, 140
Spirifer barrealensis, 138; cf. aschensis, 139
cf. mexicanus, 136
saltensis, 138
cf. simensis, 139
supramosquensis, 135
wynnei, 136

Spiriferina zewanensis, 139

151

152

INDEX

General

Abaet6, 64, 70
Accra, 10-11
Adiantites, 36, 40

Afro-American landmass, 1, 97, 99, 107, 109
rupturing of, 108, 117, 119
Agoniatites, 100
Agua Suja, 70, 83
Alethopteris, 95
Alhuampa, 46, 58, 77
Alkaline rocks, 114
Amazon syncline, 13, 15

valley, Carboniferous, 57, 101, 104,
H7-I49

valley, Devonian, 61, 99, 115
Ambocoelia, 147-149
Amygdaloid, 84, 92, 95
Anaplophora, 45

Andes, 14, 45, 108. See Cordillera
Andesite, 48, 89

Andine foldings, 14, 28, 42, 107-108, 117,
120

Angola, 9, 16, 107, 1 14, 1 17
Annular ia, 32, 77
Anodontophora, 82, 150
Araucaria, 55
Archaean :

Africa, 6
Brazil, 13, 115
Archaeopteris, 36, 40
Areado sandstone, 70
Argentina :

Carboniferous, 29-41
compared with Australia, 34, 39-41,
54, 103, 106

Devonian, 22, 33, 35, 55, 98, in
Gondwana, 22-58

glacials, 14, 22-25, 28, 30-36, 41,

Ordovician, 19, 28, 31-32, 56
Silurian, 18, 28, 97-98
Arthrophycus, 19
Assunguy series, 59, 63, 114
Asterocalamites, 36-37
Asuncion, 60, 77
Athyris, 101
Atlantic basin:

central rise, no
origin, 108, 119
volcanicity, 103, 108, no
Atlantic coasts, 15-16, 18, 107, no, 117
comparison, 1516
Atrypa, 19

Austral Devonian faunas, 6, 12, 16, 22, 99
Australia, comparison with Argentina, 41,
. 54

Avicula, 45

Bahia, 13, 16, 64-65, 95~96, 107, 114

Bahia Blanca, 14-15, 19, 27, 107, 110-111

Baiera, 47-48, 50

Bajo de Velis, 37, 39, 43~44

Balcarce, 19

Bambuhy series, 63-64, 70, 114
Barreal, 34~35, 4 7, ioi, 131, 148-149
Basaltic lavas:

Argentina, 27, 48, no
Brazil, 14, 89-94, Io6, 113

Basaltic lavas — continued
South Africa, 8, 106, 113
Basement rocks, 6, 13-15, 64-65, 115
Bauru beds, 61, 86, 96
Beaufort series, 8, 105
age, 8
flora, 8, 13

Bello Horizonte, 63-64
Benguella, 9, 15
Bermejo series, 55-58
age, 57

glacials, 58, 103
Bituminous shales, 48, 50, 69
B6a Vista, 65, 114
Bokkeveld beds, 6, 12, 112
Argentina, 20, 22, in
Bolivia, 98
Brazil, 59, 60, 112
Falklands, 12
fauna, 100
Bolivia:

Carboniferous fauna, 56-57, 147-149
Carboniferous flora, 40
Permo-Triassic, 55-58
Siluro- Devonian, 97-98
Bonito beds:
age, 78

Argentina, 76, 85, 92
Brazil, 75-76, 112
coals, 75-76
flora, 77
Paraguay, 77
Uruguay, 69, 76

Boreal, Devonian faunas, 16, 61, 99, 100
Botrychiopsis, 36, 40
Botucatu beds, 83, 85-87, 90, 106, 113
interbedded lavas, 90
Boulder:

Beds. See Glacials
Pavements, 24, 34, 102
Brasilides, 14, 18, 62, 96
Brazil :

Carboniferous marine, 13,72, 101, 147
Cretaceous, 61, 86, 96
Devonian, 13-^15, 60-61, 99, 100, 112
Permo-Triassic, 75-95
Pre-Cambrian, 15, 64-65
Triassic marine, 81-82, 150
Brazilian Coal Commission, 66, 75
Bushveld sandstone, 8, 106, 113
Cagapava, 63, 84
Cacheuta, 50, 54
Calamites, 40

Calchaquenos, 28, 31, 35, 50
Calvinia, 7
Camarophoria, 135
Cameroons, 10-n, 16, 114
Campinas, 70, 74, 76
Cape, geology, 6-9
Cape Corrientes, 1 8
Cape Fold-ranges, 7, 14, 19, in
Cape system, 6, 12
Capetown, 15, 62
Caraga quartzite, 64
Carboniferous :

Amazon, 13, 101, 147

INDEX

153

Carboniferous — conti nued
Argentina, 29-41

fossils described, 131-149
affinities, 147-148
horizons, 146-147
Asia, 1 47-1 49
Bolivia, 56-57, 148
Chile, 51

Eastern Brazil, 13, 96
flora, 29, 37, 39-41, 100
glacials, Falklands, 12

South Africa, 7, 19, 101-102
South America, 15, 30-35, 72, 100
conformity below, 7, 23
glaciation, 1 01-104
movements, 6, 100
ocean, 1 00-10 1, 104
Peru, 100, 148
Russia, 1 47-1 49
South Africa, 7
Western Africa, 11
Cardiopteris, 29, 36-38, 40, 103
Carpinterfa, 31, 36, 40
Cave sandstone, 8, 88, 90, 106, 113
Ceara, 13, 16, 114
Ceres, 7, 102
Cerro Bold, 37, 39, 45-46
Bonete, 23, 25
Largo, 63, 67, 73, 76, 81, 84
Morado, 46
Pelado, 32, 37-38
Challao, 48
Chapada, 61, 87
Chemnitzia, 56
Cherts, 80-82
Chile, Carboniferous, 51
Liassic, 107
Rhaetic 50
Triassic, 50-51
Chiropteris, 54
Chubut, 51, 107-108
Cladophlebis, 47, 49, 50, 54, 89
Clanwilliam, 15, 60, 102, m-112
Clarkeia, 98
Coal measures, 8
Coals :

Bonito, 75-76
Chile, 50

Paganzo, 32, 38, 46-47, 53
Uruguay, 76
Cochabamba, 56
Congo, 9, 16

Congo basin, 9, 95, 106, 114
glacials, 10, 58

Continental disruption. See Displacement
Hypothesis
Copiapo, 50

Cordaites, 36-37, 39-41, 77
Cordillera, 32, 50-51, 56, 108
Cdrdoba, 45, 53
Corumbatahy beds, 80-81
Cretaceous :

Argentina, 27, 47-48, 52, 55, 58, no
Brazil, 14, 16, 61, 9=5-96, 113-114
Mediterranean facies, 16
Movements, 10, 51, 107, no
Ocean, 107, 119
Patagonia, 14, 52

Cretaceous — continued

South Africa, 9, 52, in
Western Africa, 10, 16, 114
Culm flora, 32
Curitiba, 71, 108
Cuyaba, 61

Cyzicus, 47, 50, 52, 54, 113
Dadoxylon, 13, 47, 75, 79, 82
Damuda series, 8
Devonian:

Amazon, 13, 15, 61, 100, 115
Argentina, 22, 33, 35, 55, 98, hi
Bolivia, 55, 57, 61, 97-9 8, 100
Brazil, 14—15, 59-61, 100, 112
change facies, 22
Climate, 99, 100
Falklands, 12, 100
faunas, 99, 100

austral, 6, 12, 16, 22, 99
boreal, 16, 61, 99, 100
North American, 99, 100, 145
ocean, 99, 100, 115
oscillations, 99
Sahara, n, 16, 99, 100, 115
South Africa, 6, 12, 16, 100, 111-112
Uruguay, 60, 62
Western Africa, n, 15, 100, 115
Diamantina, 64-65, 108
Diamonds, 59, 61, 64-65, 114-115
Discina, 72

Displacement Hypothesis, 1,2, 17, 41, 9 7,
108-110, 118, 121
arguments for, 103, 109, 115
graphic representation, 116
Dinosaurs, 89, 113
Dogger, 51
Dolerites :

age, 15, 94- 106
Brazil, 81, 93~95, 106, 113
Falklands, 13, 102
South Africa, 9, 94, 106, 113
Dolomite:

Argentina, 18
Brazil, 65, 114
Congo, 10
South Africa, 6
Uruguay, 63, 67
Drakensberg volcanics, 8
Durazno, 74
Dwyka series, 7
age, 7

glacials, 7, 112

in Argentina, 22-25, 30-36, in
in Brazil, 70-72, 74-75
in Falklands, 12
in Uruguay, 67-69, 73-74
shales, 7, 16

White band, 7, 78, 80, 104-105
Brazil, 80

Earth movements. See Foldings
Ecca series, 7, 8, 77, 112
age, 8, 77
facies, 7, 8
flora, 8, 13

in Argentina, 21, 26, in
Eocene, 10, 16
Eogene, 107
Equisetites, 57

154

INDEX

Eremopteris, 40
Espinago quartzites, 64-65
Estancia beds, 64, 95, 114
Estheria, 47-52, 54“55, 89, 1 13
Estrada Nova group, 80-84
age, 82, 150
break in, 82, 85
fossils, 81-82, 150
Eurydesma, 104
Falkland Islands, 11-13, 99, 102
Devonian, 100, 102
geodesic position, 13, 16, 102, 117
glacials, 12, 102
tectonics, 11, 102
Famatina, 38, 44-45, 99
Favosites, 63
Fenestella, 34, 56, 132
Flora:

Bonito, 77-78
Carboniferous Peru, 100
Ecca, 8, 77
Lafonian, 12-13
Liassic, 55
Molteno, 54
Paganzo, 37-41
Trias-Rhaetic, 49, 50, 54
Foldings:

Andine, 14, 28, 42, 107-108, 117, 120
Brasilides, 14, 18, 62, 96
Cape, 7, 14, 19, 107
Cretaceous, 10, 51, 107, no
Gondwanides, 18, 26-27, 46, 52, 62,
105, 107, hi
Hercynian, 27

Permo-Triassic, 18, 27, 46, 105
Tertiary, 14, 28, 42, 120
Forest sandstone, 18, 88, 91, 106, 113
Fraile Muerto, 63, 67-69, 73, 79, 81
Furnas sandstone, 59-61, 71, 98, 112
Gangamopteris, 12, 32, 36-38
flora, 7, 16, 77
Glacials :

Argentina, 14,22-25, 28,30-36,41, 1 1 1

age, 35, 39, 4L 7§, 103, 149
Bolivia, 58

Brazil, 14, 70-72, 74~75
Congo, 10
Falklands, 12, 102
marine, 33-35, 72, 104
Uruguay, 67-69, 73-74
Glaciation, Carboniferous, 101-104, 119
causes, 104
centers, 101-104, 112
striated surfaces below, 7, 12, 30, 33,
35, 68, 103

Glossopteris, 12, 36-38, 40-41, 49, 77, 82
flora, 12, 14-16, 37, 39, 41, 44, 77,
104-105, 1 19

Gold coast, 10, 15, 99, 100, 114-115
Gondwana beds:

Argentina, 22-58
Brazil, 13-14, 70-72, 74-96
Falklands, 12

Flora. See Glossopteris Flora
South Africa, 7, 8
Uruguay, 67-69, 73-76
Gondwanaland, 1,2, 14, 78-84, 87-93, 99,
100, 103, 105, 118-120

Gondwanaland, breaking up, 107-108
glaciation, 1 03-1 04

Gondwanides, 18, 26-27, 46, 52, 62, 105,,
107, in

Goyaz, 61, 74, 79, 82, 87, 94
Grao Mogul, 64-65
Gravatahy, 72, 83
Guandacol, 35
Halobia, 51
Hastimima, 79
Hercynian folds, 27
High-level gravels, 19, 26-27, io7, 111
age, 27, 107
Hilario, 47
Holcostephanus, 52
Homalonotus, 99, 100
Huasco, 50
Interglacial zones, 25
Ipswich series, 52, 54
Iratf, 78, 82

group, 16, 78-80, 84, 95, 104, 1 12
fossils, 79
limestones, 78
Paraguay, 79, 82
South Africa, 80, 112
Uruguay, 69, 78
Itabirite, 64
Itarare series, 69, 70-74
banded shales, 73
base, 68-69, 71-72, 1 12
center of glaciation, 74-75
fossils, 72

source of erratics, 74
uneven floor, 71, 73
Jachal, 35, 98-99, in
Jaguariahyva, 60, 70
Jujuy, 43, 56
Jurassic, 46, 55, 107
erosion, 96
transgression, 107
Kalahari, 16, 91, 114
Kaokoveld, 7, 15, 106, 112
Karroo, 15
basin, 66
system, 7-9

Argentina, 23-26, 42, 54

Brazil and Uruguay, 71, 78-80,,
85, 88-89, 92-93, 101-106,
m-113

Falklands, 12-13, 16
Kimberlite, 113
Kuibis, 6

Kundulungu, 9, 10, 96, 114
Kuttung series, 40-41
Lafonian system, 12, 102
Lages, 72

Lake Titicaca, 40, 56-57, 98, 100
Land-bridges, 1, no, 118
La Rioja, 42, 45, 99
La Ternera, 50, 55
Lavras series, 64-65
Lebombo, 52, 106
Leoncito Encima, 33
Lepidodendron, 36-37, 39, 40, 77
Lepidophloios, 77
Leptoccelia, 35, 99
Liassic :

Argentina, 51, 54

INDEX

155

Liassic — continued

Argentina flora, 54
volcanics, 51, 107
Chile, 50

Dolerites, 15, 94, 106
Limestones :

Argentina, 18-19
Brazil, 61, 114
Congo, 10
South Africa, 6
Uruguay, 62-63, 6 7
Lingula, 57, 60, 72
Lualababeds, 9, 95
Lubilache beds, 9, 95, 106, 1 14
Liideritz, 6, 15, 62, 114
Lycopodiopsis, 77, 80, 95
Maldonado, 63
Mandiyuti conglomerate, 57
Maranhao, 13-14, 16, 94, 106, 114
Marattiopsis, 49
Marayes, 47, 52
Marechal Mallet, 81-82
Mariental, 7, 72, 112
Materal formation, 57
Matto Grosso, 14-15, 61, 79, 89, 99, 100
Mearim series, 95
Megalodus, 82, 150
Melania, 56
Melaphyre, 45, 51, 92
Melilite basalt, 113
Melo, 63, 67, 76, 79, 81-82
Mendoza, 45, 48-49, 52, no
Mesosaurus, 7, 16, 79, 105, 112
Minas, 63

Minas Geraes, 13, 64
Minas series, 64-65
Miocene elevation, 27
Molteno beds, 8
age, 8, 54
flora, 8, 54
Monograptus, 98
Montevideo, 62, 84
Moscovian, 35, 149
Myophoria, 82, 150
Nama system, 6, 18, 62-63, 114
Neocomian:

Argentina, 16, 52
Cape, 16, 52

Neogene, 14, 16, 43, 66, 85-86
Neuquen, 16, 52, 106-107, no
Neuropteridium, 36-37, 77
Nevado de Famatina, 38, 44-45, 99
New South Wales, 34, 39, 77, 103-104
Nigeria, 10, 99, 114
Noeggerathiopsis, 37
Northern Carboniferous flora, 38, 40
Olavarria, 18, hi
Oquita formation, 57
Ordn, 43
Orbicuioidea, 60
Ordovician :

Argentina, 19, 28, 31-32, 56
Bolivia, 97
Brazil, 13-14, 62-63
Uruguay, 62-63, 68
Orleans conglomerate, 72, 77
Ouro Preto, 64-65
Pachycardia, 82, 150

Paganzo system, 14, 28-54, 112-113
coals, 32, 38, 46-47, 53
description, 43-54, 58
distribution, 42-43, 46
flora, 37-41
folding, 31, 46
marine facies, 34-35
name, 41

overlapping, 39, 43
stages, 43 >

unconformity below, 28, 30, 33, 35,

38, 46

volcanics, 45-46
Palermo shales, 75-76
Palmeira, 78, 80, 83

Pampean formation, 16, 18-19, 27, 106,

ranges, 52-53
Paraguay :

Bonito, 77
Devonian, 60
Estrada Nova, 82
Gondwana, 60
Iraty, 79, 82
Triassic, 87
Paramillo, 47-48
Parana, 14, 59, 61, 63, 70, 83, 87
Basin, 66-94, io4
Devonian, 15, 59, 60
Parnahyba, 13
series, 94

Passa Dois series, 78-82, 85
composite character, 82, 85
in Argentina, 85
mollusca, 82, 150
Patagonia, Cretaceous, 27, 55
Patagonides, 103, 107
Pennsylvanian, 40-41
Peralta, 25
Permian:

Argentina, 14, 25-26, 43-45
Bolivia, 57
Brazil, 13, 94-96
movements, 10, 18, 27, 46, 105
South Africa, 8, 112
Pernambuco, 13
Peru, 40-41, 100

Carboniferous, 100, 148
Petroleum, 50, 58, 80
Phacops, 61
Phoenicopsis, 47, 54
Phyllotheca, 37, 46, 57-58, 77
Piauhy, 13, 16, 94, 1 14
Pillahuincd beds, 19, 25-26, 31
Pipe amygdaloid, 48, 92, 113
Piracicaba, 71
Pirapora sandstone, 96
Plants, fossil. See Flora
Pliocene, 50, 107
Polypora, 34

Ponta Grossa, 59, 60, 70-72, 75
shales, 59, 60-61, 98, 112
Porto Alegre, 72, 75, 78, 83, 86-87
Porto Uniao, 71
Potosi, 56, 1 01
Potrerillos, 49, 50
Pre- Cambrian,

Brazil, 15, 64-65

156

INDEX

Pre- Cambri an — continued
Cape, 6, 15
Southwest Africa, 6
Pre- Cordillera, 14, 27, 33, 41, 46
Productus, 34, 51, 56, 101 , 104, 147-149
limestones, 148
Psaronius, 80, 94-95
Pseudamusium, 34
Pseudomonotis, 51
Pyramboia group, 83, 86-87
Quaternary, 28, 43, 117
Quartz prophyry, 51-52
Queensland, 40-41, 54
Radioactivity, 104
Red beds, 8, 85, 89, 113
Reptilian fossils, 8
Rhacopteris, 29, 36-38, 103
Rhaetic:

Argentina, 42, 45-55
Brazil, 14, 89
Chile, 50
Floras, 50, 54
South Africa, 8, 54
Rhipidopsis, 37
Rhodesia, 8, 88, 106
Rhyolite, 52, 107
Rinconada, 36
Rio Claro, 81-82, 94
Rio do Rasto group, 81-89, 9U JI3
origin, 87

overlapping, 83-85

Rio Grande do Sul, 66, 72, 75, 81, 86, 92
Rio Sauce Grande conglomerate, 24
Rio (River) :

Atuel, 27, 51, 54
Choapa, 51
Chubut, 51
de Jejenes, 31, 36-37
de la Mina, 28, 31, 38
Grande, 28-32, 36-37
la Plata, 15

Negro (Argentina), 108
Negro (Brazil), 70-72
Negro (Uruguay), 60
Neuquen, 51
Niger, 11, 114
Parnahyba, 94-96
Sao Francisco, 13, 15, 63
Sauce Grande, 19, 20, 22-23, 27> 102
Rivera, 87, 89

Roches moutonn£es, 7, 30, 69, 74
Rocinha limestone, 80, 83
Sagenopteris, 83
Sahara, 11, 16, 57, 99, 100
Saharides, 10
Saldan, 53
Salta, 55, 58, 99
Salt Range, 104, 148
Samaropsis, 78
San Cristobal, 76, 85, 87, 92
San Jorge formation, 16, 108
San Juan, 28, 41-43, 101, 103-104, 110-11
Sanogasta, 44
San Rafael, 27, 32
Sao Bento series, 85-93
age, 89
area, 89
fossils, 89

Sao Bento series — continued
origin, 88

Sao Jeronymo, 72, 75

Sao Paulo, 63, 71, 74, 76, 78-79, 81, 83,
94, 105, 108, 1 14

Santa Catherina, 71, 80, 83, 86-89, 93
system, 14, 42, 66-94

Argentina, 76, 85, 92-93
classification, 67
overlapping, 72-73, 83
Santa Cruz:

Bolivia, 55, 57
Patagonia, 51, 55
Santa Maria, 87, 89, 91, 93
Scaphonyx, 89
Schizodus, 79
Schizoneura, 46, 58
Semionotus, 48-49, 54, 95
Serra Geral eruptives, 84, 89-93
age, 93
petrology, 93
thickness, 92
Serra Grande series, 94
Serrinha, 59, 70

Sierra Chica de Zonda, 28-32, 35-36, 38-39
de Cerro Blanco, 46-47
de Cordoba, 43, 46, 53
de la Huerta, 52
del Alto, 55-56

de la Ventana, 19-27, 99, 102, ill
folding, 20-21, 25, 102, hi
shale band, 21
quartzites, 21, 62, 102, 111
tillite, 22-25, 102, hi
de los Llanos, 37, 39, 44
de Mandiyuti, 55, 57
de Paganzo, 46

de Pillahuinco, 19, 20, 23-25, 102

de Sanogasta, 43

de Tandil, 18, 63

de Umango, 35, 43

deVelazco, 37, 39

de Vilgo, 43

Leone, 11, 15

Pintada, 22, 27, 32, 51, 105, 107
Valle Fertil, 36, 43, 46
Villa Unidn, 35, 43, 46
Sigillaria, 32, 77, 95
Silurian, Amazon, 13, 15, 115
Argentina, 18, 28, 97-98
Bolivia, 100
ocean, 97-99

Western Africa, 11, 15, 115
Solenomorpha, 81, 150
South Africa compared with South
America, 15-16, 19, iio-m
South America, geology, 13-14
South Atlantic, 108
Southern Flora. See Glossopteris flora
Southwest Africa, 6, 7, 79, 93, 102, 104,
112-114

Sphenophyllum, 77
Sphenopteris, 36, 40-41
Spirifer, 34-35, 56, 60, 63, 99, 101, 104,
1 47-1 49

Spiriferina, 34, 56
Stenopteris, 54
Stephanian, 39

INDEX

157

Stereosternum, 79, 80, 95
Stormberg series, 8, 42, 88, 113
age, 8, 54
divisions, 8
transgression, 8, 113
volcanics, 8, 52, 106
Stromatopora, 19
Sucre, 98

Table Mountain sandstone, 6, 12, 20,
in-112
age, 98

Argentina, 21, 111
Bolivia, 98
Falklands, 12
glacials, 6

Tacuaremb6, 74, 76, 79, 81, 84, 87, 89, 90
Tasniopteris, 47-48, 50, 54, 82
Taquara, 86-87, 90-92
Tatuhy group, 76
Tertiaries :

Argentina, 28, 52, 108, ill
Brazil, 13, 95, 108
South Africa, 9, hi
Western Africa, 10
Tertiary foldings, 28, 107-108, 120
high-level gravels 19,26-27,107
Thinnfeldia, 8, 46-48

flora, 16, 45, 53, 106, 1 13, 1 19
Tibagy, 59, 60, 70, 75

sandstone, 22, 60, 112
Tillite:

Argentina, 14-15, 19, 22-25, 3°~3U
33-36, 44
Bolivia, 58
Brazil, 70-71, 74
South Africa, 7
Uruguay, 68, 73-74
See Glacials
Tinogasta, 44
Togoland, 10, 16
Tombador series, 64
Tontal series, 33
Tornquist, 20
Torres, 13, 66, 87, 89
Tostado, 76, 92
Trapiche, 37
Traps, 86, 89
Trias-Rhaetic :

Argentina, 47-56, 58

Trias-Rhaetic — continued

Brazil, 13-14, 61, 67, 80-93
Chile, 50
Patagonia, 51, 55
South Africa, 8, no
Uruguay, 80-91
Triassic:

Argentina, 45-46, 92
Bolivia, 56

Brazil, 13-14, 61, 67, 80-91, 95
climate, 87-91, 106, 113, 119
Congo, 9

Marine, 45, 50, 81-82, 150
tuffs, 51-52

unconformity below, 8, 14-15, 27, 32,
42, 46-47, 50, 67, 74, 83-85, 105,
no

volcanics, 27, 51-52, 85, 94, 119
Trigonia, 52
Tropidoleptus, 60
Tuberao series, 75-77, 84
Tucumdn, 43, 55
Uitenhage, 52, no
fauna, 16, 52

Argentina, 16, 52, in
Uralian, 35, 40, 56
Uruguay:

Devonian, 60, 62
Gondwana :
coals, 76

glacials, 67-69, 73-74
volcanics, 84, 90-93
Ordovician, 62-63, 68
Uspallata, 32, 49, 51
Volcanics:

Liassic, 51, 107
Paganzo, 45-46
Serra Geral, 89-93

Argentina, 85, 92-93
Stormberg, 8, 93-94
Triassic, 48, 51-52, 85, 90-94, 119
Wegener’s Hypothesis. See Displacement
Hypothesis
Western Africa, 10-1 1
Westphalian, 39, 40
White band, 7, 78, 80, 112
Witteb erg series, 7, 12, 102
Argentina, 20, in
Falklands, 12

PLATES

I. Folded Devonian quartzites, Sierra de la Ventana.

II. A. Shale band in Devonian quartzites, Sierra de la Ventana; B. Cleavage in til-
lite, Sierra de la Ventana.

III. A. Tertiary “high-level gravels,’' Sierra de la Ventana; B. Lower glacial zone,

Sierra Chica de Zonda, San Juan.

IV. A. Glaciated surface beneath lowest glacial zone, San Juan; B. Lowest glacial

zone, Sierra Chica de Zonda, San Juan.

V. A . Second glacial zone, Sierra Chica de Zonda, San Juan; B. Second glacial zone,
Sierra Chica de Zonda, San Juan.

VI. Second glacial zone, Sierra Chica de Zonda, San Juan.

VII. A. Second glacial zone, Sierra Chica de Zonda, San Juan; B. Dome in Paganzo
beds, Carpinterla, San Juan.

VIII. A. Dome in Carboniferous beds, Barreal, San Juan; B. Paganzo beds, Bajo de
Velis, San Luiz.

IX. Triassic beds, Barreal, San Juan.

X. A. Tree-trunks in Triassic beds, Paramillo de Uspallata; B. Triassic beds,
Marayes, San Juan.

XI. A. Triassic conglomerates, Saldan, Cordoba; B. Triassic conglomerates, Capilla
del Monte, Cordoba.

XII. A. Devonian Furnas sandstone, Ponta Grossa, Parana; B. Rio do Rasto sand¬

stones, Taquara, Porto Alegre.

XIII. Carboniferous fossils, Barreal, Argentina.

XIV. Carboniferous fossils, Barreal, Argentina.

XV. Carboniferous fossils, Barreal, Argentina.

XVI. Carboniferous fossils, Barreal, Argentina .

m l! BRMtf M THt

27 1928

UNlVttlSMY 01 tU'N°*s

158

Carnegie Inst. Wash. Pub. 381

PLATE I

Folded Devonian quartzites north of the Cerro Naposta Grande, looking east

From a photograph by Dr. R. Beder

Carnegie Inst. Wash. Pub. 381

PLATE II

A — Shale band in quartzites of the Sierra de la
Ventana gorge below the Tres Picos

B — Cleavage in tillite, railway cutting a little northeast of Sierra de la Ventana station

THE LIBRARY

OF THE

UHIVERSITY OF ILLINOIS

Carnegie Inst. Wash. Pub. 381

PLATE III

A — Tertiary “ high-level

gravels" on folded Devonian beds, west side of the Arroyo San
Bernardino, Sierra de la Ventana

B — Lower glacial zone, immediately to the north of the Rio Grande, Sierra Chica de Zonda,

San Juan

Carnegie Inst. Wash. Pub. 381

PLATE IV

A — Glaciated surface of Ordovician limestone beneath lowest glacial zone, a little north of
the Rio Grande, Sierra Chica de Zonda, San Juan; the hammer indicates the direction
of the glacial striae

B — The lowest glacial zone, resting on tilted Palaeozoics, followed by plant-bearing shales
crowned with sandstones, a little north of the Rio Grande, Sierra Chica de Zonda,
San Juan

THE LIBRARY

OF THE

HMIVERSITY OF ILL!

Carnegie Inst. Wash. Pub. 381

PLATE V

A — Second glacial zone, a little north of the Rio Grande, Sierra Chica de Zonda, San Juan.
The dark tillite forms the central peak and is sandwiched between well-stratified beds;
the third glacial zone forms the point on the extreme left

B — Second glacial zone, Arroyo de Jejenes, San Juan. Below are sandstones, followed by
the glacials with lens of sandy material and overlain by sandstones which form the
summit of the cliff

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The second glacial zone, Arroyo de Jejenes, San
Juan, showing lenticular band of sandy material

Carnegie Inst. Wash. Pub. 381

PLATE VI

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Carnegie Inst. Wash. Pub. 381

PLATE VII

A— The second glacial zone, Arroyo de Jejenes, San Juan, showing practically

unstratified tillite

B— Dome in Paganzo beds, followed by tilted Calchaquenos and overlain by horizontal

Quaternary gravels; west of Carpinteria, San Juan

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Carnegie Inst. Wash. Pub. 381

PLATE VIII

A — Dome in Carboniferous beds near Quebrada del Salto, Barreal, San Juan, showing in
foreground boulder shales and fossiliferous shales, followed by sandstones forming
the hills in the background

B— Plant-bearing Paganzo beds, Bajo de Velis, Sierra de San Luiz. The range in the back¬
ground is made of crystalline rocks

> •

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PLATE IX

A — Triassic plant-bearing strata of Stage IV, Quebrada del Jarillal, Barreal;

on extreme right beds of Stage V

B — Triassic beds of Stage IV, overlain by the red conglomeratic strata of Stage V

Quebrada del Salto, Barreal, San Juan

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PLATE X

A — Tree trunks standing erect in Triassic volcanic ash, Paramillo de Uspallata

B — Tilted sandstones and conglomerates of the coal-bearing section of Stage IV, Carrizal

near Marayes, Sierra de la Huerta, San Juan

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PLATE XI

B — Triassic conglomeratic sandstones, Los Terrones, near Capilla del Monte

Sierra de Cordoba

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Carnegie Inst. Wash. Pub. 381

PLATE XII

A — Devonian Furnas sandstone, showing current-bedding. East of Ponta Grossa, Parana

B — Rio do Rasto " millet-seed " sandstones, municipal quarry, Taquara, near Porto Alegre.
The marked dip from left to right is due to false bedding, the formation being actually
horizontal

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Carnegie Inst. Wash. Pub. 381

PLATE XIII

Carboniferous Fossils, Barreal, Argentina

(i) Orbiculoidea saltensis sp. nov. (7335), upper valve. X 1.5. (2) Productus ( Marginifera )

spinulo-costatus Abich var. nov. peregrina (7374), pedicle-valve. X 1.25. (3) Spiriferina zewanensis
Diener (7312), pedicle-valve. X 1.5. (4a, 46) Productus curvirostris Schellwien var. nov. barrealensis
(7315), pedicle-valve, a, top view; b, front view. X 2. (5) Hemiptychina cf. sublcevis Waagen (7300),

pedicle-valve. X 3- (6) Choneles granulifer Owen (7319), pedicle-valve (shell partly wanting). X 1.5.

(7) Nuculana ( Leda ) cf. bellistriata Stevens (7339), internal cast. X 2. (8a, 8 b) Reticularia notica sp. nov.

(7326); a, pedicle-valve. X 1.5; b, portion of shell. X 8. (9) Productus lineatus Waagen (7365), side view,

pedicle-valve. X 2. (10) Reticularia notica sp. nov. (7445), pedicle-valve. X 1.5. ( 1 1 ) Pseudamusium

stappenbecki sp. nov. (7291), left valve. X 1.5. (12) Pseudamusium cf. elliplicum (Phillips) (7304), left

valve. X 1.5. (13) Pseudamusium stappenbecki sp. nov. (7290), right valve. X 1.5. (14) Aviculopecten

barrealensis sp. nov. (7362), left valve. X 4.

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PLATE XIV

7b 8b

Carboniferous Fossils, Barreal, Argentina

(i) Spirifer of. supramosquensis Nikitin (7316), pedicle-valve. X 1.25. (2) Spirifer barrealensis

sp. nov. (7371), pedicle-valve. X 1.5. (3) Spirifer mexicanus Shumard var. nov. neolropica (7366), pedicle-
valve. X 1.25. (4) Spirifer mexicanus Shumard var. nov. neotropica (7375), pedicle-valve. X 1.25. (5)

Spirifer aff. rajah Salter (7317), pedicle-valve (anterior part bent underneath). X 1.5. (6) Spirifer

( Martinia ) cf. simensis Tschernyschew (7363), pedicle-valve. X 1.5. (7 a, 7b) Spirifer Wynnei Waagen var.
nov. argenlina (7309), a brachial valve, X 1.25; b front view. X 1.25. (8a, 8 b) Spirifer saltensis sp. nov.

(7296); a, pedicle-valve. X 1.5; b, brachial valve. X i.S-

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PLATE XV

3 c

Carboniferous Fossils, Barreal, Argentina

(i) Euomphalus subcircularis Mansuy (7328), base. X 1. (2) Euomphalus subcircularis (7344)

apical surface. X 1.25. (3a, 3 b, 3c) Pleurotomaria argentina sp. nov. (7334); a, b, side-views. X 1.5; c, por¬
tion of base. X 6. (4) Euomphalus subcircularis (7322), apical surface. X 1.25. (5) Pleurotomaria

advena sp. nov. (7355)- X i-5-

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Carnegie Inst. Wash. Pub. 381

PLATE XVI

Carboniferous Fossils, Barreal, Argentina

Pleurotomaria barrealensis sp. nov. (7323) ; a, side view. X 1.5; b, base, X 1.5.

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CARNEGIE INSTITUTION OF WASHINGTON

PUB. No. 381

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