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/ BULLETIN

OF THE

MUSEUM OF COMPARATIVE ZOOLOGY

AT

HARVARD COLLEGE, IN CAMBRIDGE.

VOL. XLIV.

(GroLoeicaL Series, VII.)

CAMBRIDGE, MASS., U.S. A.
1901-1904.

UNIVERSITY PRESS:

JoHn WILson AND Son, CAMBRIDGE, U.S. A.

613348
7. SS

Bulletin of the Museum of Comparative Zoology
AT HARVARD COLLEGE.
VoL. XLIV.

GEOLOGICAL SERIES, Vol. VII.

THE STONE REEFS OF BRAZIL, THEIR GEOLOGICAL AND
GEOGRAPHICAL RELATIONS, WITH A CHAPTER
ON THE CORAL REEFS.

By Joun Casper BRANNER.

WitH NINETY-NINE PLATES.

CAMBRIDGE, MASS., U.S.A.:
PRINTED FOR THE MUSEUM.
May, 1904.

The Stone Reefs of Brazil, their Geological and Geographical
Relations, with a Chapter on the Coral Reefs.

By JouHn Casper BRANNER.

TABLE OF CONTENTS.

J. INTRODUCTION . . . Aaa? 4
II. SKETCH OF THE Gaesoce! OF THE Coase IN ITS pavitrons TO THE

SToNE AND CorAL REEFS 8

Pre-Cretaceous RC n Rhee! he Pn et Ae Rb iwa RE ost « 8

The Cretaceous . . Syiok t! «chai ate ee eee 9

What is the age of the Bahia beds ? mnie eh 5.5 g

Conclusion regarding the Bahia beds 11

iiheareomotmemcoastisediments ny. i Soke Ss ss OS
icweriioenoMcolortoape. . = 2 4a sible eeiote ne es 3 «|| 18
ithe Rertiary beds‘okthesAmazonas.. .0.0 5 2 si... es §6=628
TCHAPCERUCIiNtEyeGGDOSIES..! a) ac) 24 (oh A tees. Gee ew he ORT
Recent deposits . . . Sere ce en cs Ol
Conclusions regarding the pole of the ae Hep rece AL oe
III. DetTa1ILeD DESCRIPTIONS OF THE SANDSTONE REEFS -. .... 34
The Ceara stone reef . . ena Pe giriP est 46 BA
The stone reef at Rio Grande fio Marka: speisen eee ewes ies os a OO
The Pirangy rock reef ... . AOR res sh rc or AO
The stone reefs of the Cunhaht and Sifaman OPP. Pee ns oy AO
iemlrricrolStOnue recta mt: site ch sees s- S eetare Aalra. 63s, AB
The Mamanguape stone reef . . Bo bye i ey Nf
The consolidated beaches of Parahy ba de maces Rego beret § 00
The Pedra de Galé or Goyanna stone reef .. ....... . «486
SEeelrORDOCeIstONe TeAi yf w.s Ulett) Be. Gyeti se wee. wet. . . 69
hos ReEAMbDUCORtONe eel 1. fs sn. sk sta eo 60
The beach reef at Piedade . . . Sie “gris, 3. OF
The stone reef at Venda Grande, Pernambuco fit arte ee.) (BO
The Gaibti stone reef. . . en eee ce "69
The stone reef south of Cabo Santo eeeaukoe ete Per Ge 611
Thetbeach rocks at Corto de Gallinhas.>. 2. .253 oe 2 ww OT
The: Cacimba and Serinhaem stone reefs .'. . 2... =... 179
‘Rhemrone eck Ol SantoeAlerxon =) oil. es waar ake. w . 80
The sandstone reef of Rio Formoso. . . Ae fe ss, Si
The stone reefs of the Rio Sapucahy, Alagéas AMP sk so < OS
The stone reefs of the Pratagy, para ER ee al Bestest. «OL
The stone reefs of Bahia . . Oke, SEA oR ei eae eRe 5}
Mherstone reek at SantavOruz. 0. ah Mee ek wise leriel als - «©6956
CnreMerterk GEE OrtO SegUTO™ - 0. ae tee es. | OT
Notes upon little-known stone reefs... .........- 99
MirealancaueHloealiticsa cs! 2vicc | «9 «i ectes ete ae easaetc . 6101

VOL. XLV. 1

BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

IV. ConcLUSIONS REGARDING THE FORMS AND STRUCTURE OF THE
SronE REEFs .
The shore beach
The off-shore beach
Application to the Breeding stone neers
Structure of the stone reefs .
Conclusions
V.. THe ‘ELEVATION AND Dipaceenes OF THE Noprannes Goa OF
BRAZIL 3
Changes of the reefs Pathe meen ie
Observations of others : :
Have there been changes within the historic period? 2
Conclusions ;
Changes within recent cedar periods
Views of former writers . ‘
‘The schistose structure of the eeeeeee
The dip of the reef rocks .
Reef rocks above high tide
Lakes near the coast
The fixed dunes of the cay
Islands joined to the mainland .
The straightening of the coast-line
Comparative effects of elevation and depression
Effects of elevation .
Effects of depression
Forms on a stationary coast .
Application to Brazil
Evidences of depression
Open bays .
Coast lakes . a, .. 42 jeepers e
Rios tapados
Choked embayments
Depressed valleys :
The case of Rio Sao Peanenwes
Evidence of the'islands: = =) i.) se reeenec nnn
Offshore clays : ;
Evidence of buried foc chaaneis ;
Additional views of depression
Evidences of elevation ‘
Elevated beaches, State of Alagoas :
Elevated beaches, State of Bahia
Marine terrace at Ilheos, Bahia
Lagoa de Itahype 58
At Ponta d’Areia, Bahia .
At Victoria, Espirito Santo .
Elevated sea-urchin burrows
The death and decay of the coral reefs!
Time relations of the elevations and depressions .
Influence of the coral reefs .
Influence of the mangues
Hyacinths : Pee oe ts ic
Origin of the coast le: a a ae, oh Severe olan

PAGE

110

111

167

BRANNER: THE STONE REEFS OF BRAZIL.

Conclusions regarding coast changes
VI. Tue ConsoLiDATION OF THE STONE REDFS
The cement

Analysis of rock from the page meee se Rio Mermcse:
The microscopic examination of thin sections of sandstone on the

Rio Formoso reefs :
The origin of the cementing sratenral

Cement from the beach sands by rain-water or spray .

Lime carbonate from the ocean

Carbon dioxide of submarine pelcemiconcint :
Carbon dioxide from sea-water, but not of eruptive origin .

Is the process universal ?

Lime carbonate from the fond é :

The consolidated beaches of the Bevan
Relations of density to deposition

The seaward percolation of acid lendewater :

Possible influence of climate

The hardening process is not a badaintioas: one .
Conclusions regarding the consolidation of the reefs .

VIL Tue AGE OF THE SANDSTONE REEFS
Stratigraphic relations
Physiographic relations

The fossils in the reefs

Conclusions

VIII. AnnoTaTEeD BEE anor y. OF THE Srone Beas, OF BRietE :

Résumé of the Pasa a
IX. THE Corat REEFS

Local details .
The Rocas .
Cape St. Roque ae
Lavandeira reefs .
Joao da Cunha reef .
Ceara reefs . ae
Fernando de Noronha . .
The coral reef of Parahyba a Marta’

Coral reefs between Parahyba and Recife .
The coral reefs from Pernambuco to Santo Aleixo

Santo Aleixo

The coral reefs Beiwect nite Algae ind Neacbio ;

Analysis of reef rock
The Bahia reef es
Reefs between Itaparica and Gaearelins.
Coral reefs off Caravellas .
The Abrolhos reefs . :
Thickness of the coral reefs of Brwil
The age of the coral reefs 2
The chemical composition of Brazilian corals
List of the corals of the coast of Brazil .

Notes on the corals collected. By A. W. Gescleyn

The Maceio coral reef .

Résumé of conclusions regarding fae coral eo
EXPLANATION OF THE PLATES .

te)

4 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

LE.

Introduction.

THERE is no more striking geologic phenomenon along the eastern
shores of South America than the stone reefs of Brazil.

These reefs are supposed by many persons to be of coral, and this error
has been propagated by writers of books of travels and by works on the
navigation of the south Atlantic. There are several reasons for this
error : coral reefs border many tropical coasts in a similar manner ; there
are extensive coral reefs on the coast of Brazil ; the stone reefs of Brazil
are unique, or rather they are found nowhere else in the world except
on a very limited scale ; seen from a vessel sailing along the coast or
even near at hand, the stone reefs are scarcely distinguishable from
coral reefs even by an expert; and, finally, the sandstone reefs are
generally covered with calcareous growths common to coral reefs. The
only thing that is especially characteristic of the form of stone reefs
is their straightness, and this is not always apparent to one looking at
them either from the shore or from the ocean. In Brazil the only men
who really seem to know the difference between the two kinds of reefs
are the lime-burners who make lime of the corals, and a few of the
masters of barcacas, or sugar boats. Among these men distinction
is made between the coral rock, which they know as pedra de cal (lime
rock), or as cabega de carneiro (sheep’s head, referring to Porites and
other solid heads), and the sandstone which they call pedra de encantaria ;
that is, stone used for window and door sills and facings, as the reef
rocks have been used from the earliest times.

In a sense the sandstone reefs are local, but the forces and agencies
that have formed them have been in operation along the entire coast,
from near Maranh&o to southern Bahia, while local conditions have pre-
vented their formation at some places, or have favored their preservation
or destruction at others.

The ports and towns behind the stone reefs owe everything to them.
Without these reefs there would be no Pernambuco, no Rio Grande do
Norte, no Porto Seguro, no Santa Cruz, to say nothing of the minor
ports like Rio Formoso, Serinhaem, Sudpe, Traigéo, Mamanguape, and

BRANNER: THE STONE REEFS OF BRAZIL. . 5

many others where the sugar boats load and take refuge along the whole
coast from southern Bahia to Ceara and Maranhao.

The geological and geographical peculiarities of these stone reefs con-
sist in the facts that —

I. They are of sand consolidated to a hard —in places almost
quartzitic — sandstone.

II. They stand about flush with the water at high tide, while at low
tide they are left exposed like long, low, flat-topped walls, with a width
of from five metres to one hundred and fifty metres, and a length of
from a few paces to several kilometres.

III. They accompany the shore line with many and great interrup-
tions from north of Ceara to Porto Seguro, a distance of two thousand
kilometres.

IV. With unimportant exceptions the reefs do not occur along the
Brazilian coast beyond these limits.

V. They usually stand across the mouths of streams and estuaries
forming perfect natural breakwaters for the small harbors behind them.
Sometimes they follow the shore, either on the beach or at a short
distance from it.

VI. They are all nearly straight. When crooked, their curves are
gentle.

VII. The structure and position of the reefs and the animal remains
they contain show that they have been made by the lithification of
beach sands in place.

VIII. When stone and coral reefs occur together, the stone reefs are
inside or landward of the coral reefs. It is possible, however, that there
may be buried coral reefs in some cases to the landward of some of the
stone reefs.

IX. The coral reefs are now growing over and upon the stone reefs in
some places, while at other places there are stone reefs overlying dead
coral reefs.

X. In general appearance, elevation, and position the sandstone reefs
bear a striking resemblance to the coral reefs.

My work on the reefs was begun in 1875-6-7, while I was a member
of the Commissao Geologica do Brazil ; it was extended at subsequent
visits in 1881—2—3, and ended in June, July, August, September, and
October, 1899, when an opportunity was afforded me by Dr. Alex-
ander Agassiz to finish it. This last visit has been of the utmost
importance, for I have thus been able to revise earlier and less trust-
worthy observations, to visit new localities, and also to study the prob-

6 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

lems that present themselves after a more thoughtful consideration of
the whole subject.

Like so many of the problems that seem simple and easily disposed of
at the outset, this one has turned out to be much less simple than was
anticipated. And even now, after having worked at it for twenty-five
years, I am more than ever impressed with the complexity, difficulty,
and far-reaching nature of the problems surrounding these sandstone
reefs. Above all, it seems evident that any satisfactory theory of these
reefs must include the study of the geographic development of the coast-
line, —a study not hitherto attempted. Certain theories that have been
advanced in explanation of or in connection with these reefs are not
discussed in the present paper because they are without the bases that
would entitle them to serious consideration. One of these is the theory
of their glacial origin.’ It has already been shown that there is no satis-
factory evidence of glacial action in Brazil.? Another is the theory of
the orographic relations of the reefs to the western Alps. This idea
was suggested to Liais by the once famous but now almost forgotten
Systemes de Montagnes of Elie de Beaumont.®

The problems of the coral reefs have long been before the scientific
world. I have not been able to undertake any comprehensive study of
the coral reefs of Brazil, but I hope that this approaching of the subject
from the geological and geographical side may throw some light upon
these problems, so far at least as this particular coast is concerned.
In discussing the coral reefs I have endeavored to weigh the evidence at
my command and to reach logical conclusions unbiassed by any particular
theory.

There are several related topics which it was intended to discuss in
connection with the ones here dealt with, such as the currents, winds,
tides, submarine topography, and submarine erosion, but the paper is
already too voluminous and those parts are omitted.

A great desideratum in studying the history of the Brazilian coast is a
good topographic map. This does not exist. The hydrographic charts

“are the only ones available, but these dea] only with such features as
interest navigators, while the maps of the interior are often little more
than vague generalizations. It is cause for congratulation that several
of the Brazilian states under the lead of SAo Paulo, whose survey is

1 Nouvelle géographie universelle. Par E. Reclus. Tome XIX. Amérique
du Sud, p. 222. Paris, 1894.

* The supposed glaciation of Brazil. By J.C. Branner, Journ. Geol. L, p. 7538-772.

3 L’Espace Celeste. Par E. Liais, p. 544, 548. Comptes Rendus, 1860. L.,
p. 762-768.

BRANNER: THE STONE REEFS OF BRAZIL. t 7

headed by our able fellow-countryman, O. A. Derby, are undertaking
topographic maps.

Many kind friends have placed me under obligations by their cordial
assistance in connection with this work. Mr. Whitaker, formerly Presi-
dent of the Geological Society of London, has helped me with valuable
references. At Washington, Mr. Hay, Secretary of State, kindly fur-
nished me with letters to the diplomatic and consular representatives of
the United States in Brazil, and procured for me letters from the
Brazilian minister at Washington to the governors of the Brazilian
states to be visited.

In Brazil, the governors and the American representatives were
extremely obliging ; without their co-operation it would have been im-
possible to carry on my work. Mr. Guy Swift of Pernambuco, the
former head of the firm of Henry Forster and Company at that place,
has, by his high standing as a business man and his acquaintance with
the country and the people, been of the greatest possible service. Mr.
Kenneth C. Macray of Maceio, by his kindness and hospitality, made it
possible for the expedition to accomplish at that place much that without
such aid could not have been done.

As stated above, the last expedition in connection with this work was
made in 1899, and was provided for by Dr. Alexander Agassiz. I was
accompanied by several volunteer assistants: Ray Collins, B. H. Collins,
Harold Havens, and C. E. Gilman, at that time students of geology in
Stanford University. Mr. Gilman made most of the maps of special
areas. My principal assistant was Dr. Arthur W. Greeley, now of
Washington University, at St. Louis, who had entire charge of the bio-
logic work. Dr. Greeley prepared the paper on the corals at the end of
this report. The materials collected by him were sent to specialists, and
the following papers have already been published upon them by the
Washington Academy of Sciences: “Crustacea” by Mary J. Rathbun ;
““Tsopod Crustacea,” by Harriet Richardson; ‘ Mollusca,” by W. H.
Dall; “Fishes,” by C. H. Gilbert.

The original maps accompanying this paper —those by Messrs. Gil-
man and Havens—were made with a six-inch compass needle for
taking bearings, while distances were either paced or determined by
triangulation. The long reefs were all paced; the isolated rocks were
located by triangles.

8 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

TE

Sketch of the Geology of the Coast in its Relations to the
Stone and Coral Reefs.

PAGE PAGE

Pre-Cretateons- . ° 02. nic A ay The relation of colortoage. . 18
The Cretaceous . . 2 The Tertiary beds of the ers

What is the age of the Bahew beds? 9 zonas . . SP ca ewe 381

Conclusion regarding the Bahia The later Tertiaey dempnites rh pee’

beds) cath betpas celal: Recent deposits . . . 31
The age of the anes coast ace Conclusions regarding the: eae

DNCHEB..) os. io We 6 Aeon ee es ogy of the coast .~ -.e5 5-7 om

The discussion of the stone reefs of Brazil is both a geological and a
geographical one. It is therefore necessary to get our geological orien-
tation, —to have some idea of the general geological history of the
region discussed, before treating of the reefs themselves. This is essen-
tial, because the reefs are of late geological origin, and it is necessary
to understand the geological history of the coast in order to see where
the reefs came into that history. It is also the more necessary on ac-
count of many statements in the present paper that do not agree with
earlier publications regarding the geology of the region here treated.

Pre-Cretaceous.— The principal feature of the coast geology with
which we have to deal is a series of mechanical and organic sediments
forming a plateau along nearly the whole of the coast from the northern
part of the State of Rio Grande do Norte to the State of Espirito Santo,
—a distance of nearly two thousand kilometres. Over most of this dis-
tance these sediments rest upon crystalline rocks,—in some places
granites, in other places gneisses, in others schists. These old crystalline
rocks are cut here and there by eruptive dikes of later age. The age
of the old underlying beds is not known, but the schist series looks very
like the Algonkian of Van Hise. At one place — the Serra of Itabaiana,
in the State of Sergipe —there are older sediments between the erys-
talline rocks and the later sediments known to be of Cretaceous age.
No fossils have been found in these lower beds, but from their position
below the Cretaceous beds they have been provisionally assigned to the

BRANNER: THE STONE REEFS OF BRAZIL. 9

Palaeozoic.! They might with just as much propriety, however, be re-
ferred to the Jurassic or Triassic. So far as the present discussion is
concerned, the age of these pre-Cretaceous beds is a matter of but little
importance. Our present interest is chiefly with the Cretaceous and
with the post-Cretaceous history.

The Cretaceous. — There are marine Cretaceous beds in the State of
Sergipe resting upon the Palaeozoic and crystalline rocks of the interior,
but how far north and south these beds extend is not known at present.
It is quite possible that a narrow strip of Cretaceous rocks extends up
and down the coast for a long distance, and it is possible, too, that the
bottom part of the series here set down as Eocene is really Cretaceous.

What is the age of the Bahia beds ?— There has been some confusion
in the classification of the Cretaceous and Tertiary beds of the east coast
of Brazil. It is necessary, therefore, to bring together the evidence
upon which the classification is based, and to ascertain, if possible, which
beds are Cretaceous and which Tertiary. Without entering into de-
tails it may be accepted as satisfactorily proved that the highly fossilif-
erous beds of the Sergipe basin are Cretaceous. The fossils from these
beds are described by Dr. C. A. White in his excellent monograph.?
Some of the other beds, however, have been referred to both Cretaceous
and Tertiary. Inasmuch as the rocks of the Bahia sedimentary basin
have yielded more palaeontologic evidence than any one locality outside
of Sergipe, the age of the beds of that region will be considered first and
in more detail. It is with these that we now have to deal.

The earliest paper in which a definite geologic age is assigned the
coast sediments is one by J. F. M. Von Olfers, published in “ Karsten’s
Archiv fir Mineralogie, etc.,” IV. 173-180, at Berlin in 1832 under the
title, ‘‘ Ueber das niedrige Felsenriff der Kiiste von Brasilien.” In this
paper the author puts down as Tertiary the stone reefs, the sandstones
of the Amazon valley, the rocks of the Bahia basin, and all the sedi-
mentary beds from Maranh&o to the Abrolhos. He makes no mention,
however, of any palaeontologic evidence of the ages of any of these rocks.

In 1836 Charles Darwin touched at Bahia, and though he does not
give their names, he speaks of having found Tertiary fossils at the head
of the Bay.®

1 J. C. Branner, the Cretaceous and Tertiary geology of the Sergipe-Alagéas
Basin. Trans. Amer. Phil. Soc., XVI., p. 881-382. Philadelphia, 1889,

? Archivos do Museu Nacional, VII. Rio de Janeiro, 1887.

3 Charles Darwin, Geological observations, 2 ed. London, 1876, p. 198, foot-
note.

10 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY.

a ialhe She

paper on Brazilian geology,’ in which he speaks of the Bahia sediments
as both marine and fresh-water Tertiary. The only mention Pissis
makes of palaeontologic evidence is (p. 398) that the beds contain fossil
pectens, oysters, and cythereas, — genera which later collectors have
not found there, and which, if found, would not alone fix the Tertiary
age of the beds.

In 1859 Prof. T. Rupert Jones described a small collection (five
species) of Entomostraca from Bahia. Professor Jones said of these
fossils that they appear to be allied to recent and Tertiary species. In
the same place 8S. Allport describes vertebrate remains from the Bahia
beds, among which are the scales of Lepidotus. These two papers of
Allport and Jones are the first we have that afford definite palaeontologic
evidence of the age of the Bahia sediments. Unfortunately the evi-
dence is conflicting from the very beginning: the Entomostraca are
allied to recent and Tertiary species, while the Lepidotus is a Cretaceous
species.”

In 1869 Marsh described * from the Bahia basin Crocodilus harttii,
which he says resembles a species from the Miocene of Virginia, and
another from the Tertiary of New Jersey. Another fossil vertebrate,
Thoracosaurus bahiensis, he says, is probably allied to the modern
gavials.

In 1870 Hartt’s book on the geology of Brazil® appeared, in which
he speaks of the beds of the Bahia basin as lower Cretaceous (p. 350),
and possibly Necomien (p. 555). He describes from these beds a few
new fossils, and gives much data upon the details of geologic structure
about the Bahia basin, but there is nothing that can be regarded as
having diagnostic value in a doubtful case, and no palaeontologie evi-
dence to warrant the reference of some of the beds to the Lower Creta-
ceous and others to the Tertiary (p. 377).

1 Mémoire sur la position géologique . . . de la partie australe du Brésil. Mém.
de l'Institut de France, X. p. 353-412.

2 On the discovery of some fossil remains near Bahia in South America. S.
Allport, T. Rupert Jones, Note on the fossil Entomostraca from Montserrate.
Quarterly Journal Geological Society, December, 1859, XVI. p. 263-268. Lon-
don, 1860.

8 O. C. Marsh, Notice of some new reptilian remains from the Cretaceous of
Brazil. Amer. Journ. Sci., XCVIL., p. 390-392. New Haven, 1869.

* Dr. A. Smith Woodward notes that this is a detached tooth, and should not
be considered in this connection. (Private letter, Nov. 7, 1902.)

5 Ch. Fred Hartt, Geology and physical geography of Brazil. Boston, 1870.

BRANNER: THE STONE REEFS OF BRAZIL. LIE

In 1886 Cope described vertebrate fossils from Bahia.’ One of these
—a fish, Diplomystus— had not hitherto been known below the Green
River Eocene of North America, but has since been found in the Creta-
ceous of Lebanon, Syria, and now living in the rivers of Chili and in
New Zealand. A mammal, Toxodon expansidens, from the northeastern
part of the State of Bahia, is set down by him without question as of
Pliocene age, but this without doubt comes from beds other than those
referred to the Cretaceous.

In 1887 Dr. C. A. White’s great work on Brazilian fossils was pub-
lished.?, The Bahia basin is there set down as Cretaceous. In review-
ing the palaeontologic evidence bearing upon this subject, Dr. White
says that only eleven species of mollusks are known from the Bahia
beds, and he makes this important observation (page 233): ‘‘ All the
types which this fauna embraces, so far as they are determinable, are
represented among mollusks now living.”

In 1888 Dr. A. Smith Woodward published notes on fossils from
these beds,’ in which he mentions the occurrence of Diplomystus longi-
costatus Cope ; Chiromystus mawsont Cope; Lepidotus mawsoni Wood-
ward ; Acrodus nitidus Woodward.

In 1891 Dr. Woodward published evidence * of the occurrence of
Pterosaurians and Plesiosaurians in the Bahia beds. In 1895 he de-
scribed two species of Diplomystus from the same basin ;*° in 1896 he
described from there a Pterodactyle bone,® and in 1902 he described
Megalurus mawsont from the Bahia beds.’

Of these vertebrate fossils reported by Dr. Woodward, the Pterosau-
rians suggest that the beds are either Jurassic or Cretaceous ; the Plesio-
saurians suggest that they are Jurassic; the Diplomystus suggests that
they may be anywhere from Cretaceous to recent; the Pterodactyle
suggest that they are certainly Cretaceous or older ; and the Megalurus
that they are Upper Jurassic.

Conclusion regarding the Bahia beds. — The papers by Dr. Woodward
afford the latest and by far the most conclusive palaeontologic evidence

1 KE. D. Cope, A contribution to the vertebrate paleontology of Brazil. Proc.
Amer. Phil. Soc., 1886, XXIII., p. 1-21.

2 Contribuigodes 4 Paleontologia do Brazil. Archivos do Museu Nacional, VII.
Rio de Janeiro, 1887.

3 A. Smith Woodward, Notes on some vertebrate fossils from the province of
Bahia, collected by Joseph Mawson. Ann. Mag. Nat. Hist., ser. 6, II., p. 132-136.
London, 1888.

4 Ann. Mag. Nat. Hist., ser. 6, VIII., p. 314-317. 5 Op. cit., ser.6, XV., p. 1-3.
§ Op. cit., ser. 6, X VIL, p. 255-257. 7 Op.cit., ser. 7,1X., p. 87-89.

12 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

of the age of the Bahia beds, and this evidence certainly points to their
Cretaceous or even earlier age. The evidence favoring the Tertiary
age of the beds, however, cannot be overlooked. Without the verte-
brate fossils we should have been compelled to call the Bahia sedi-
ments Tertiary. When, however, all the data now available are taken
into consideration, one of the following solutions to the problematic
combination seems possible : —

I. It is possible that there are two or more well-defined formations
(Cretaceous and Tertiary, and possibly others), but that for lack of
proper stratigraphic and palaeontologic work they have not been defined
and separated.

II. It is possible that both Cretaceous and Tertiary are represented,
but that there is no stratigraphic or faunal break between them in that
region.

III. It is possible that in Brazil we have a fossil fauna unlike any
that characterizes either Cretaceous or Tertiary of other parts of the
world ; that is, that some of the Tertiary forms of North America began
during Cretaceous times in Brazil, or that the Cretaceous forms of other
parts of the world survived into the Tertiary in Brazil.

I was formerly disposed to think the first suggested solution the
correct one. The little I have seen of the Bahia basin inclines me to
think that the beds containing fossil Mollusca near the Montserrate fort
overlie and are northwest of the beds yielding most of the vertebrate
fossils. The latter beds contain heavy conglomerates at the base and
rest against the granites. But whether beds of two separate ages exist
on the coast of Brazil or not, studies of the living molluscan and coral
faunas of the Brazilian coast and their comparison with the faunas of
Florida and the West Indies lead to the inference that our gulf fauna
came originally from the coast of Brazil. (See Dall on Mollusca and
Verrill on corals.)

It seems not improbable therefore that the Tertiary fauna of the Gulf
States may have originated in a similar manner on the coast of Brazil,
and that in migrating northward it has undergone changes that have
caused it to diverge somewhat from its parent stock, while the Brazilian
fauna of the same age may have retained some of its Cretaceous aspects.

Since the above was written I have asked the views of Dr. A. Smith
Woodward. In reply to an inquiry regarding his conclusions based upon
the vertebrate fossils he writes under date of Nov. 7. 1902: “I consider
that Lepidotus, Acrodus, Dinosaurs, and Pterodactyls prove that the
Bahia sandstone fauna is Mesozoic. There is, of course, some reason to

BRANNER: THE STONE REEFS OF BRAZIL. 1h

suspect that Dinosaurs lived later in South America than elsewhere.
(See Proc. Zool. Soc., 1901, I. 182.)”

The age of other coast sediments. — The above conclusions are based
upon materials from the Bahia basin. How far they are applicable to
the other regions, — that is, to the Pernambuco, Parahyba do Norte, and
Para regions, — hitherto set down as Cretaceous, it is not possible at
present to say. Some of the Bahia beds are of fresh or brackish water
origin ; it is therefore difficult to correlate them with marine beds in
distant parts of the country, and it is necessary to consider separately
the evidence found outside of the Bahia basin.

As has already been pointed out, Olfers called all these coast sedi-
ments Tertiary, but he says nothing of palaeontologic evidence. In 1836
Darwin examined the sedimentary beds near Pernambuco and speaks of
them as Tertiary,’ but he says that he looked in vain for organic remains
in them.

In 1846 George Gardner considered the sedimentary beds at Rio
Formoso on the Pernambuco coast to be Cretaceous like those of the
interior of Ceara,’ but as he reported no fossils from them no importance
was attached to his opinion.

Fossils have now been found in the coast sediments (outside of the
Sergipe and Bahia basins) at the following places: Olinda (Hartt,
Branner), Maria Farinha (Hartt, Derby, Branner), Itamaracd (Branner),
Ponta de Pedras (Branner), Parahyba do Norte (Capanema, Agassiz,
Sumner), Jacuma (Branner) ; in the State of Rio Grande do Norte at
Mossoro (?) and Apody ; and also at Pirabas (Penna) in the State of Pard.
In addition to these stations fossils have likewise been found at a few
points in the interior of Parahyba do Norte and of Rio Grande do Norte.?

In 1859 the “Commisao Scientifica” of Brazil touched at Parahyba
and Bardo de Capanema says: “ A badly preserved crinoid leads me to
suppose that the rock belongs to the Cretaceous.” 4

In April, 1867, E. Williamson read before the Manchester Geological
Society a paper upon the geology of Parahyba and Pernambuco,® in

1 Charles Darwin, Geological observations, 2 ed. London, 1876, p. 193.

2 George Gardner. Travels in the interior of Brazil, p. 103-104. London,
1846. Rio Formoso is not specifically mentioned by Gardner, but his observations
regarding the locality and his notes upon the voyage leave but little doubt about
that being the place referred to.

3 Bull. Geol. Soc. Amer., XIII., p. 56-57.

* Trabalhos da Commissio Scientifica de Exploracdéo I Seccio Geologica, p.
CXXII. Rio de Janeiro, 1862.

° E. Williamson, Geology of Parahyba and Pernambuco gold regions. Trans.
Manchester Geol. Soc. 1866-67. VI., p. 113-122.

14 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

which he says there are Tertiary and Cretaceous rocks in the region, and
he seems to mean that the upper colored beds somewhat resembling
the New Red Sandstone of England are Tertiary, and that the impure
limestones beneath them are Cretaceous. He mentions no fossils, how-
ever, and gives no reason for calling either of the series by these names.

In 1865, Prof. Louis Agassiz touched at Parahyba do Norte, and
Hartt states that he found there fossil estherians from which he (Hartt)
infers that the deposits are of fresh-water origin and equivalent to the
Bahia beds which he regarded as of Cretaceous age." This, however,
was not published until 1870.

Later Hartt set off from the beds later accepted as Cretaceous an
upper and apparently a well-differentiated series of highly colored and
mottled beds, and cailed them Tertiary. This scheme first appeared in
1868,? but was treated more fully in his book that appeared in 1870,°
and again in a paper read before the American Geographical Society in
1871.4

This designation of the colored beds, afterwards known as the Ter-
tiary, commended itself so favorably to field geologists in Brazil that it
was immediately accepted,® though Hartt himself observed afterwards
that ‘one may find variegated clays on the Amazonas containing Devon-
ian and Carboniferous fossils.© And yet no one ever succeeded in all the
thousands of kilometres of exposure in finding a single well-defined line
of division between the Cretaceous and the supposed Tertiary beds,” and
no one found a fossil in the so-called Tertiary ones, with the possible
exception of the fossil plants found within the last few years in the State
of Bahia, the age of which has not yet been determined. But aside
from these two important wants, the assignment of the horizontal colored
upper beds to the Tertiary appeared to be a proper one, and no especial

1 Geology and physical geography of Brazil, p. 445.

2 C. F. Hartt. Résumé of a lecture on the growth of the South American con-
tinent, p.5. Reprinted from the Cornell Era of Dec. 12,1868. Ithaca, N. Y., 1868.

3 C. F. Hartt. Geology and Physical Geography of Brazil, p. 557. Boston,
1870. ;

4 Ann. Rep. Amer. Geogr. Soc. Vol. III., p. 231-252.

5 The present writer published in 1889 a paper upon the Cretaceous and Ter-
tiary geology of the Sergipe-Alagéas Basin of Brazil. (Trans. Amer. Phil. Soc.,
XVI., p. 369-434) in which he followed Hartt’s division.

6 Amer. Journ. Sci. 1872. CIV., p. 57.

7 Both Hartt and Williamson say the Tertiary overlies the Cretaceous uncon-
formably. Geol. and Phys. Geogr. of Brazil, 557; Résumé of a lecture on the
growth of the South American continent (Ithaca, N. Y., 1868), p.5. Trans. Man-
chester Geol. Soc., 1866-67, VI., p. 114.

BRANNER: THE STONE REEFS OF BRAZIL. 15

difficulty seemed to be encountered in dealing with them assuch. From
1870, when Hartt’s book was published, down to the present time, these
unfossiliferous party-colored beds have been called Tertiary.

In 1875 Richard Rathbun published a paper upon the lamellibranchs
found in the vicinity of Pernambuco.!. The materials were from three
localities in the vicinity of Maria Farinha, eighteen miles north of Per-
nambuco. Although the title of Mr. Rathbun’s paper shows that the
beds were regarded as Cretaceous, all the species in his list are new
except two; and among those described are Cucullwa harttii and Venert-
cardia (Cardita) morganiana, which, if found in North America, would
be regarded as Tertiary.

In Dr. White’s monograph published in 1887 are described more fully
the molluscan collections from Maria Farinha in the State of Pernam-
buco, and from Pirabas,? State of Parad. The localities yielding these
fossils are likewise set down by White as Cretaceous in spite of the
fact that they contain such characteristic Tertiary forms as

Hercoglossa (Nautilus) sowerbyana d’Orb.
Volutilithes radula (Sowerby) Forbes.
Mazzalina (Fasciolaria) acutispira White.
Pseudoliva (Harpa) dechordata White.
Cucullea harttii Rathbun.

Calyptraphorus ? chelonites White.
Venericardia (Cardita) morganiana Rathbun.

It cannot be denied, however, that some of the fossils from Maria
Farinha are of decided Cretaceous aspect.

When Dr. White undertook the study of the Brazilian Cretaceous
(and Tertiary) fossils collected by the Commissio Geologica it was ex-
pected that he would remove any doubts that might exist in regard to
the ages of the formations represented. But instead of weighing the
evidence and reaching an independent conclusion, he accepted without
question the earlier inference of Hartt. I would not imply that Dr.
White failed to do his duty in this matter. The fact is that the collect-
ing was not done so that he could have made a separation of the faunas
if it had been otherwise possible. I say this the more frankly because
most of the fossils described by him were collected by me. But at that

1 Richard Rathbun. The Cretaceous Lamellibranchs collected in the vicinity
of Pernambuco, ete. Proc. Boston Soc. Nat. Hist., X VII., p. 241-256. Boston, 1875.

2 In Dr. White’s Contributions this place is called Piabas, but a later paper by
Drs. Huber and Kraats, who visited the locality in 1898 (?) shows that the correct
name is probably Pirabas.

16 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

time I was altogether unacquainted with the distinction between Cre-
taceous and Tertiary fossils, and I knew next to nothing of the care and
discrimination required in such collecting. I now recall the fact that
at one of the Maria Farinha localities I sifted fossils out of piles of re-
siduary earth that might have represented several different formations,
and all of these went.to Dr. White simply as having come from Maria
Farinha.

At a place on the northern coast of the State of Pernambuco called
Ponta de Pedras I found sedimentary beds containing fossils that

Fie. 1. Ponta de Pedras, State of Pernambuco. The fossiliferous rocks
are exposed along the beach.

strongly resemble those found at Maria Farinha. These fossils were
examined by Dr. Ralph Arnold, who kindly made the following determi-
nations and correlations : —

FossiIts FROM PoNnTA DE PEDRAS, Coast OF PERNAMBUCO.
Also found at —

1. Cypreacteon penne White . . . . Rio Pirabas.
2. Volutilithes radula (White, not Sow eo . Olinda; Maria Farinha.

Volutilithes alticostatus White ; :
Z - ‘ : Maria Farinha.

2 V. radula White

4. Acmea sp. nov.

5. Natica or Neverita sp. undet . . . . . ~~. Montserrate, Bahia.
6. (Neritina prolahiata White)

7. Turritella elicita (White, not Stolitzka) . . Maria Farinha.

8. Vicarya ? daphne White .. .. . . . . Maria Farmha.
9. Capulus sp. nov.
10. Amalthea sp. nov.

a a”

BRANNER: THE STONE REEFS OF BRAZIL. 17

Also found at —

11. ? Melania terebriformis Morris? . . . . ~ Itamaracd; Montserrate,
Bahia.

12. Crepidula sp. nov.

13. Lucina tenella Rathbun . -. . =. - ~~. Rio Pirabas; Maria Fa-
rinha.

14. Nucula marie Rathbun. . . . . Maria Farinha.

15. Leda (Nuculana) swiftiana Rathbun . . . Maria Farinha.

16. Corbula i chordata White . . . - -. -.- Maria Farinha; Sergipe;

Rio Pirabas.
17. Corbula sp. nov.
18. Dosinia brasiliensis White . . - . . . Sergipe; Rio Pirabas.
19. Glycymeris (Axinea) bineminis White soy s. oo a keoPirabas.
20. Cardiwm (Criocardiwm) soaresanum Rathbun Maria Farinha; Itamaraca.

Of the twenty species here listed, five are new, five are reported from
Rio Pirabas, State of Para, nine are found at Maria Farinha, two at
Montserrate, Bahia, two in the State of Sergipe, and one at Olinda,
Pernambuco. ‘Two were also found at a new locality discovered by the
writer at the northeast end of the island of Itamaraca. The specimen
from Itamaraca was found in a bed of brown sandstone. The Itamaraca
locality is only eleven kilometres south, and Maria Farinha is only
twenty-seven kilometres south of Ponta de Pedras.

The resemblance of the fauna found in the Ponta de Pedras rocks to
that of the Maria Farinha beds is at once apparent, while the proximity
of the localities to each other bears out the theory that the same beds
are repeated at these two or three localities.

At Parahyba do Norte, on the other hand, have been found a few
fossils, one of which —a species of Sphenodiscus — is so characteristic a
Cretaceous genus that it seems impossible to doubt the Cretaceous age
of the beds from which it came.! The same beds have yielded a species
of Cimolichthys, another Cretaceous genus.

On account of his acquaintance with South American palaeontology I
have asked the opinion of Dr. A. E. Ortmann of Princeton regarding the
possible Tertiary age of some of the beds yielding the fossils described
by Dr. White. He writes me as follows :—

Princeton, N. J., 27 July, 1902.

Dear Sir, — Thanking you for your letter of May 9th I may say that I
have used White’s paper on the supposed Cretaceous in Brazil for comparison
with my Patagonian fossils; but, of course, I did not make a very careful
search for allied species, since I took it for granted that we have to deal here

with Cretaceous beds.
1 Bull. Geol. Soe. Amer. XIII., p. 48.

MOS XIV: 2

18 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

But since you called my attention to the probable Tertiary age of at least a
part of these deposits, [ have examined the matter more closely. I find that
your contention that part of these beds is Tertiary (Eocene) is well supported,
and am fully prepared to accept this view.

Among the fossils, there are not many that show affinities to our Patagonian
(Miocene) forms, which is probably due to their older age (Kocene). But
nevertheless there are a few relations. The following are the most striking.

Ostrea distans White, from Para. This is a characteristic Tertiary type,
allied to our O. ingens Zitt.

Gryphaea brachyoptera White, from Pernambuco, resembles G. tarda Hutt,
from the Patagonian beds.

Cardita wilmotti Rathbun, from Pernambuco and Para, resembles C. inaequalis
Phil.

Posinia brasiliensis White, from Sergipe, Para, and Pernambuco, is very near
D. magellanica Ortm. from the Magellanian beds of Punta Arenas.

Trochus retectus White, from Para, resembles Calliostoma garrett: Ortm.

Fusus pernambucensis White, from Pernambuco, comes near F. subspiralis
Ortm. from the Magellanian beds of Punta Arenas.

Calyptraea fausta White, from Para, comes near Crucibulum dubium Ortm.

It is very significant that we have two species (Posinia brasiliensis and
Fusus pernambucensis which resemble most closely species described by myself
from the Magellanian beds, which I take for Oligocene. This would furnish
additional evidence for the old Tertiary age of the Brazilian beds, and, on the
other hand, for the similar age of the Magellanian beds.

: Yours very truly, A. E. ORTMANN.

In view of his acquaintance with the Eocene of North America I have
asked the opinion of Prof. Gilbert D. Harris of Cornell University re-
garding the fossils from Maria Farinha and Pirabas, Para. Dr. Harris
writes me as follows: “I can assure you most emphatically that neither
in that work (Dr. White’s report on the Brazilian Mesozoic fossils) nor
in our specimens (at Cornell University) nor in those I have seen in the
United States National Museum from Maria Farinha, can I find a trace
of any fauna other than the Midway Eocene.”

The relation of color to age.—It has already been stated that Hartt
regards the party-colored beds of the coast of Brazil as Tertiary, and
that this long seemed to be a fairly satisfactory method of disposing of
them.! The fact that these colored beds always seemed to be horizontal,
while the Cretaceous strata were usually more or less bent, appeared to
give support to this classification.

The horizontal bedding of these rocks is sometimes more apparent

1 Geology and physical geography of Brazil, p. 557. Ann. Rep. Ree Geog. ;
Soc., IIL, p. 231-252.

BRANNER: THE STONE REEFS OF BRAZIL. 19

than real, and as the apparent bedding is associated with the coloring,
these features of the series may be treated together. Seen from several
miles at sea, the horizontality of the colors sometimes gives the rocks the
appearance of having horizontal beds, when in reality the colors cut
across the beds. At the colored cliffs just south of Rio Camaragibe in
the State of Alagdas this can be seen fairly well. The bluffs at that
place are from seventy-five to one hundred metres high and the upper
part is all highly colored. Plate 11 is taken at this locality from a
platform of unaltered rocks shown in the foreground that is covered at
high tide, when the water reaches the face of the steep bluff. These
beds dip gently toward the right at an angle of from 5° to 8°. Atten-
tion is directed to a fairly well-defined light-colored band that runs
along the top of the steeper part of the bank. This band is the lower
limit of the colored portion of the rocks in these hills, and it can be
seen even in the photograph that the line of discoloration is horizontal,
while the beds have a gentle but decided dip. Above the line of dis-
coloration the rocks are colored and mottled soft clays and sands, mixed
in all sorts of proportions, but whose bedding is more or less difficult
to trace. These are the rocks we have been in the habit of calling
Tertiary. Below the horizontal band they have their bedding perfectly
defined, and vary from coarse sandstones to fine compact shales, in color
mostly grays of various shades, and dark brown to almost. black. They
have limy streaks in them here and there, and the shales often have
a lumpy or concretionary appearance. The unaffected parts of these
beds are only from five to seven metres above tide, and the top of the
unweathered portion retains this elevation regardless of the dip of
the beds.

The line separating the colored and the uncolored portions is not a
clean-cut one. The unaffected beds can be traced upward into and
across this line; but the change is a very gradual one —it is only when
one stands away from the exposure and tries to trace out the individual
strata with the eye that he cannot do it.

Plate 12 is another view that shows well the bedding of these Cre-
taceous shales and sandstones at the same place. The lower portion
of the bluff is washed by the sea at high tide, and up to a height of six
metres these beds are dark and light grays. The top of the bluff where
the plants grow is decomposed and highly colored. The rocks dip
away from the observer at an angle of 14°, and just round the corner
shown on the left the line of Har ee cuts the tops of the series
along an approximately horizontal plane.

20 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

At the northern end of this exposure are many large water-worn
granite boulders apparently weathered from a basal conglomerate.

Going south along the coast from the Barreira do Camaragibe before
reaching the town of Santo Antonio da Barra Grande, one finds some
beautiful examples of coloring. The bluffs — there are several of them
—are about fifty metres high, and the rocks are red, pink, gray, white,
yellow, purple, orange, black, brown, and streaked and mottled, — all
combined to make a most brilliant bit of rock colormg. In the upper
part of this bluff the bedding planes cannot be made out, and even the
colors appear only in irregular blotches, streaks, and bands. But at the
base of the cliff there are some beds still clearly defined as shales and
sandstones.

At one place the upper part of the section is all gray and cream-
colored, while the lower part is fantastically splotched and streaked.
A coarse-grained sandstone is partly of a pearl-gray color with a vast

s

N

Fic. 2. Bluffs of party-colored sandstones and shales fifty metres high
north of Santo Antonio Grande, State of Alagoas.

number of sharply defined streaks and rings of brilliant cinnabar red
running through it. At two places the beds seem to be faulted, and
where the faults appear there are masses of unbedded white or gray
sandstone harder than the other rocks. These masses of sandstone have
the appearance of vertical intrusions.

The exposure that first led me to question the validity of the so-called
Tertiary division of these rocks is at a place on the Alagéas coast known
as the Barreira do Boqueirao, a few miles north of the mouth of Rio
Manguaba.

The following sketch (page 21) will give some idea of the geological
relations there exposed.

The hills at Barreira do Boqueirao are some seventy metres high, and
the dip of the rocks is mostly toward the hills. The upper part of the
hills is of red, brown, purple, and yellow clays and sands nowhere clearly

separated from each other. To the left is a bed of fossiliferous bitumi-_

nous shales, exposed for a distance of 150 metres, and dipping from 10°

BRANNER: THE STONE REEFS OF BRAZIL. 21

to 15°-N. 45° W. beneath the hill. It overlies the strongly bedded
conglomerates and sandstones exposed on the right. The dip is not
constant, however, for one hundred and fifty metres down the shore the
dip is more nearly west. The exposure of the bituminous shales shows
them to be nearly two metres thick, but it is possible that they have a
thickness of three or four metres.

Now the lower or left (south) end of this shale is a fossiliferous peaty
or bituminous bed with limy streaks and patches in it, while the upper
or right end merges into a mass of mushy nondescript purple and brown
sandy clays. Further, the discoloration has progressed more rapidly in
the sandstones beneath the shales than in the shales, so that the former
are already mottled and stained to a depth of six metres or more below

Fig, 3. Exposure on the beach at Barreira do Boqueirio.

the base of the shales. It should be added that the conglomerates of
this section contain water-worn granite boulders as large as a man’s
head.

At the City of Maragogy, State of Alagéas, only fourteen kilometres
north of the Barreira do Boqueirao, a section is exposed at the base of
the hill in the rear of the church. Here the bottom stratum, perhaps
not more than five or six metres above tide, is false bedded and mot-
tled so that it strongly resembles the bottom bed at the Barreira do
Boqueirao.

At Riacho Doce (S. lat. 9° 36’), the shales and sandstones are exposed
from the mouth of the stream southward nearly to Garca Torta. As in
many other places, they are cut off by the waves so that they are well
exposed only at low tide. They are much bent and faulted at this

22 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

place, here covered by patches of coral reefs and there by fragments of
sandstone reefs. These beds also seem to lie close to the base of the
series, for about the mouth of Riacho Doce and scattered among the
exposures are big granite boulders, many of them more than a metre
in diameter, apparently weathered or washed from a heavy basal
conglomerate.

The bituminous shales at Riacho Doce are fossiliferous, containing
abundant diatoms, pliant fragments, and fish remains. The diatoms are
fresh-water forms, while the land plants are too fragmentary for identi-
fication. One fossil fish was identified by Mr. F. A. Lucas of the U. 8.
National Museum as Diplomystus laticostatus Cope, a form that is found
also at Bahia.

The dips of the beds vary greatly in amount and considerably in di-
rection, but the general direction is landward, — toward the red bluff that
rises on the west. This bluff is a beautiful example of the weathered
sediments ; it is about a hundred metres in height, half a kilometre or
more in length, and is most brilliantly colored. Seen from the beach
half a kilometre away, the beds appear to be horizontal.

A noticeable feature of the dips at all the exposures on the coast is
that they are Jandward. A section at Riacho Doce would fit most of
the cases thus far seen.

Some of the most accessible localities at which these beds are to be
seen are at and about the city of Olinda near Pernambuco. There is a
good exposure at Olinda about a hundred metres northwest of the Vara-
douro station in the rear of a wine factory. Here the beds are horizon-
tal, lumpy, yellowish rocks containing fossils; the exposure is at the
base of the hill, and the thickness visible is six or seven metres. My
friend, Dr. Louis Lombard, formerly Director of the Escola de Engenha-
ria of Pernambuco, showed me some fossils collected by him from beds
exposed on the Olinda beach at low tide.

The hill on which the Carmo church stands is of mottled beds toward
the top, while near the base small patches of the yellowish fossiliferous
rock appear here and there. On the slope of the hill below the Church
of Sio Francisco the mottled and the yellow limy rocks are mingled in a
newly opened drainage ditch.

About a kilometre west of Olinda are some typical exposures of the
colored beds known as the Ruinas de Palmira. These “ruins” are at
about the same elevation as the upper parts of the Olinda hills.

At Maria Farinha limy fossiliferous beds are exposed about the bases
of all the hills near the mouth of the river and along the estuary for

BRANNER: THE STONE REEFS OF BRAZIL. 23

several kilometres, but in all the hill-tops the rocks are red and yellow
and mottled, and these colors descend on the slopes of the hills almost
or, in places, quite to tide level. Though I have been over these hills
many times and carefully searched for the contact between what were
formerly considered to be Cretaceous and Tertiary beds, I have never
succeeded in finding anything suggesting a line of division.

The Island of Itamaracé has limestones and calcareous sandstones
exposed about its lower levels, but its hilltops are capped with the
weathered red beds. I found fossils in the lowest beds at tide-level,
on the northwest corner of the island, but I could find no dividing line
between these and the red and yellow earths that cap the hills on this
corner of the island. Dr. Louis Lombard showed me Cretaceous
cephalopods collected by him near the southwest end of the island
from the limestone, and I was told of several lime-kilns about the
place, but over the island generally the hill-tops are of red and yellow
soil.

At the point of land about a kilometre south of Jacuma on the coast
of the State of Parahyba do Norte, the rock exposed at the water’s
edge is yellow fossiliferous calcareous sandstone like that at Itamaraca.
Within a distance of two hundred metres of the fossiliferous beds the
sea has exposed overlying colored strata at as low a level or lower, but
no dividing line can be seen between the two. They merge imperceptibly
into each other.

At Parahyba the fossiliferous Cretaceous beds are exposed near the
railway station in the cuts along the line leading to Cabedello, while the
tops of the hills on which the city is built are of the red and mottled
weathered beds. I naturally hoped to find in this railway cut, made
since my first visit to Parahyba, the contact between Tertiary and Cre-
taceous, but, as elsewhere, the two divisions merge together so impercep-
tibly that no separation can be made out though the exposure is a
fairly good one.

The colored beds cap the hills on which the city of Parahyba stands,
and continue eastward to Cape Branco, where they are well exposed upon
the beach.

In Bahia between Jaguaripe and Nazareth there are pinkish horizontal
sandstones that, according to our former classification, were included in
the Tertiary, but north of Sio Thomé on the shores of the bay, similar
sandstones have a north dip of from ten to fifteen degrees. These beds
are pink in the hill-top, but lose that color as they approach and pass
below tide-level.

24 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

This case is worthy of attention, as showing also that horizontality
which we formerly regarded as characteristic of the Tertiary in Brazil

Fre. 4. The bluff at Cabo Branco seen from the beach.

has no diagnostic value. So far as I know, the Tertiary beds of this
coast are nearly all horizontal, but the horizontal beds are by no means
all Tertiary.

A great many other instances have been observed along the coast of

BRANNER: THE STONE REEFS OF BRAZIL. 25

Bahia, Alagoas, Pernambuco, Parahyba do Norte, and Rio Grande do
Norte, but those already mentioned are enough to show beyond question
that the coloring is an accident without any evident relation to the age
of the beds.’

The Tertiary beds of the Amazonas. — Fossils supposed to be of Ter-
tiary age have been described from the upper Amazon region, but the
age of the beds referred to seems never to have been determined with
certainty, though they are evidently not older than the Tertiary. As
long ago as 1854 Foetterle spoke of the lignite beds of Iga, Tabatinga,
Loreto, and Pebas on the Maraijion, which he supposed were of Tertiary
age.”

Orton found at Pebas near the southern boundary of Ecuador fossils
which Gabb says “indicate a marine or perhaps rather a brackish water
fauna. There is not sufficient material to warrant an opinion as to the
geological age of the deposit,” but he thinks they “ point to a very recent
era.” ®

Later Mr. Hauxwell made a larger collection at Pebas and at Pichua
thirty miles below Pebas. This collection was described by Conrad, who
is doubtful about the age of the beds.* He says that the fauna “may
have lived in either fresh or brackish water, but it certainly is not of
marine origin.” The opinions of both Gabb and Conrad show that the
statement of Orton to the effect that these shells “ may be Miocene ”®
was premature. About the time that Conrad published his article there
appeared one by Woodward upon a collection from the same region.®
The author of that paper seems to take it for granted that Orton’s
opinion of the age of the beds was correct, and says nothing of any
reason for referring them to the Tertiary.

In 1872 Hartt published an article upon the so-called Tertiary basin
of the Marafion, but he never visited the region he was writing about,
and based what he said upon the papers of Orton, Gabb, and Woodward,

1 J.C. Branner. The oil-bearing shales of the coast of Brazil. Trans. Amer.
Inst. Min. Engs., XXX., p. 537-554.

2 Franz Foetterle. Die geologische Uebersichtskarte des mittleren Theiles von
Siid Amerika. p. 20-21. Wien, 1854.

8 W. M. Gabb. Descriptions of fossils from the clay deposits of the Upper
Amazon. Amer. Journ. Conchology, 1868, IV., p. 197.

4 T. A. Conrad. Description of new fossil shells of the Upper Amazon. Amer.
Journ. Conchology, 1871, VI., p. 192.

5 James Orton. The glacial deposits of the valley of the Amazons. Geol. Mag.
1870, VIL. p. 540.

6 H. W. Woodward. The Tertiary shells of the Amazons valley. Annals Mag-
azine Natural History, ser. 4, Jan. and Feb., 1871, VII., p. 59-64, 101-109.

26 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

and on the notes of Steere! Gabb’s opinion of the age of the deposits
he does not give correctly, but he quotes from Steere’s notes facts that
appear to strengthen the idea of the Tertiary age of the beds.

Dr. Oskar Boettger published in 1878 a paper upon the Pebas beds?
in which he describes several new species of fossils. He says the fossils
show the deposits to be of brackish-water origin laid down about the
mouth of a large stream, that there are no marine forms whatever, and
while he calls the beds early Tertiary he admits that inasmuch as the
fauna of the region is unknown, the age of the beds is really doubtful
(p. 503), — a view with which one must agree.

Dr. W. H. Dall writes me privately : “As regards the Pebas fossils,
they are a unique and isolated group of which it is difficult to deter-
mine the age because all the characteristic forms are extinct and have no
obvious relatives. It may be as old as Eocene or as new as Pliocene, but
not, I think, younger.” ®

In 1879 Etheridge described a collection made by C. B. Brown from
similar formations on the Solimées and Javary.* These again are spoken
of as Tertiary, but no reasons are given for this classification. Most of
the species described by all these writers are new and the collections
therefore have but little diagnostic value, especially in the absence of
a knowledge of the existing fresh and brackish water faunas of that
region.

Major Coutinho says that the formations at the mouth of the Huallaga
in Peru and at the head waters of the Japura, the Jurua, and the Puris
are the same as those of Marajé and along the coast to Piauhy.® From
his description I take this formation to be what Hartt calls Tertiary and
Agassiz calls glacial sediments. But this sweeping correlation by
Coutinho must be regarded as extremely venturesome, and certainly with-
outa sufficient basis of facts. The table-topped hills of the Amazon
valley Hartt thought were Tertiary, but in these again no fossils were
found.® Hartt says in speaking of these formations that his ‘“ opinion

1C. F. Hartt. The Tertiary basin of the Marafion. Amer. Journ. Sci., July
1872, CIV., p. 538-58.

2 Die Tertiirfauna von Pebas am oberen Marafion. Jahrb. d. K. K. Reichsan-
stalt, 1878, 28 Band, 3 Heft, p. 485-504.

3 Private letter, April 26, 1901.

4 R. Etheridge. Notes on the Mollusca ... from the Tertiary deposits of
Solimées and Javary rivers, Brazil. Quar. Journ. Geol. Soc., 1879, XX XIV., p. 82-88.

5 Bull. de la Soc. de Géographie. Paris, Oct. 1867, XIV., p. 321-334.

6 C. F. Hartt. Recent explorations in the valley of the Amazonas. Ann. Rep.
Amer. Geog. Soc. N. Y. 1870-71, p. 246.

BRANNER: THE STONE REEFS OF BRAZIL. ad

that they are newer than the Cretaceous and probably of Tertiary must
be taken for what it is worth, until the question is settled by palaeon-
tological evidence,” * and that is about all one can make of the matter.
If we grant that the upper Amazon region from Iquitos to Tabatinga is
Tertiary, there is no evidence that the mottled sediments of the lower
Amazon are of the same age, to say nothing of correlating them with
similar-looking beds on the coast of Rio Grande do Norte, Parahyba,
Pernambuco, and Alagédas — 2500 miles away. This seems also to ex-
press Professor Derby’s view of the subject.?_ They are too far from the
region discussed in this paper, and too little is known of the interven-
ing country, for us to be able to connect the two.

The later Tertiary deposits. —It seems proper to accept the general
trend of the evidence that some of the Brazilian coastal sediments are of
Eocene Tertiary age. At about a dozen known localities between Vic-
toria and Natal these Eocene or some of the older rocks have resting
upon or against them a series of soft and generally dark-colored sedi-
ments that are probably of Pliocene age. These later sediments, whether

Fie. 5. Geologic section on the beach of the Cunhahu Valley.

Pliocene or not, throw important light upon the geographical and geo-
logic history of the coast, and for that reason the notes made upon the
exposures are here given. That more facts are not at hand is due to a
great extent to the uncultivated and jungle-covered condition of the
country. The forests are thick and practically impenetrable the year
round. The few known exposures, it will be observed, are all on the sea-
shore. It is reasonable to suppose that these same rocks occur pretty
much all along the coast, but they are difficult to find even when one can
get into the vicinity of them.

Between Rio Cunhahi, S. lat. 6° 20’, and the bluffs at Bahia Formosa
is exposed along the beach a dark brown or snuff-colored soft false-
bedded sandstone. The lower part of these beds is washed by the tides,

1 Bulletin Buffalo Soc. Nat. Hist., Jan. 1874, I., p. 235.

2 0. A. Derby. A contribution to the geology of the Lower Amazonas. Proc.
Amer. Phil. Soc., 1879, X VIII., p. 176-177.

28 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

and the top of them, at a few places only, rises perhaps as much as a
metre above high tide. Sand dunes lie on top of these beds, and behind
the dunes the water soaks down, passes through the dunes, and following
along the top of the rocks issues as amber-colored springs on the beach.
At one place a large spring has cut through the rock and comes out
two metres or more below its surface. Not a trace of a fossil could be

Fic. 6. Theoretic section showing the relations of the Bahia Formosa beds
to the Cunhahti sandstone.

found in a kilometre of exposure of this rock. The beds are horizontal,
but they do not appear in the Bahia Formosa section of the colored beds
which are cut clear down to the water’s edge. The snuff-colored beds
must, therefore, rest unconformably against the valley originally cut by
the Cunhaht in these sediments.

A few kilometres north of the Cunhahi and north of Rio Sibatima, the
bluffs have lying against them at one place horizontally bedded sedi-
ments made of fragments derived
from these bluffs themselves.

These beds contain no fossils,
and from the appearance of the
materials it is supposed that the
newer beds here were deposited
since the discoloration of the
bluffs. At this place the top
of the deposit is barely within
reach of the highest spring tides.
Iam not at all sure that these
newer beds are related to the
snuff-colored ones.

Fic. 7. Section through the bluff and ¢
beach north of Rio Sibatima. At the mouth of Rio Maman-

guape, S. lat. 6° 46’, on the point
of land just east of the Barra de Mamanguape are exposed very dark
sandstones, of about the same texture as the reef rocks and containing
quartz, but in color from dark brown to perfectly black. Between the

BRANNER: THE STONE REEFS OF BRAZIL. 29

point and the village these rocks are strongly false-bedded, the false
beds being a metre thick. These black beds extend under the village
and appear at several places further up stream at low tide. The ex-
posures about the point are all covered by water during high tides.

Fie. 8. Section showing the relations of the Mamanguape reef to the
landward sandstones.

The top of these sandstones is about as high as the top of the stone
reef outside, but it was impossible to make out the structural relations of
the two. No fossils could be found in the dark beds.

At the village of Sudpe, just south of Cape Santo Agostinho, a very
black soft sandstone is exposed on the sandy beach at low tide. The
exposure is only about ten metres long. The rock contains no fossils.

At the Barra de Serinhaem, S. lat. 8° 36’, these dark soft sandstones
are exposed along the river bank at low tide for a distance of several
hundred metres. No fossils were found in them. The church stands
upon these beds which at this spot rise about two metres above high tide.

An important exposure of these rocks is uncovered on the shore be-
tween the village of Gamella and the mouth of Rio Formoso, S. lat. 8°
40’. Upstream on the north side of the river the Tertiary beds are
well exposed in a vertical bluff at the end of the hill upon which the
church stands. On the northeast side of this hill a low ridge strikes off
toward Gamella and the encroachment of the sea-upon this ridge has
exposed its rocks well. The section is shown in the following sketch.

HT.

awe ee ee ie ee ae ew 2 ee

Fic. 9. Geology of the beach at Gamella, Rio Formoso.

The beds of this section below the thin seam of yellow clay are prob-
ably Eocene Tertiary, and are exposed in the bluffs south of the church,
but the snuff-colored bed and the white sands are not in that section.

30 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

If the continuity of the two sets of beds could be seen, I should expect
them to come together in some such manner as this :

Fic. 10. Section showing the relation of Guadalupe Hill to the Gamella
beach near Rio Formoso.

Unfortunately no fossils have been found in these rocks.

Three hundred metres upstream from the mouth of Rio Maragogy,
S. lat. 9°, 3', on the south side of the stream, there are fragments of a
dark soft sandstone very like some of the beds here described, but these
beds contain a few shells, especially Venus. In the absence of these

se totes

Fic. 11. Example of erosion on the beach, Gamella. From a photograph.

shells I should have classed it with the snuff-colored beds; in the pres-
ence of them I took them to belong to the stone reef rocks, —a dis-
tinction that will perhaps give a good idea of the lack of data for the
palaeontologic classification of these rocks.

On the Rio Sergipe, nine kilometres west of the city of Aracaji, S.
lat. about 10° 52! 30”, beds similar to those above described are exposed

BRANNER: THE STONE REEFS OF BRAZIL. 31

on the east side of the river between Aracajii and Porto das Redes.
The rocks are mostly soft, but here and there they are somewhat
hardened.

Wherever the water comes from these snuff-colored beds it has a dark
amber color.

Sandstones similar to these occur on the south end of the island of
Itaparica, Bay of Bahia, just south of the village of Cata, and on the
opposite side of the passage for a kilometre or two on the east coast of
the island of Sant’ Anna. These beds have not been examined. They
are horizontal and rise two or three metres above high tide.

Near Caravellas the southeastern end of the Bahia e Minas Railway
runs for nine kilometres over a recently elevated sea-bottom. West of
kilometre 10 the line passes for five kilometres over the dark brown or
snuff-colored soft sandstones. These rocks are exposed only in the bot-
tom of the trenches beside the track. They lap over the Tertiary (?)
red beds that extend from kilometre 19 to the western edge of the Serra
dos Aymorés. Rocks of the same kind are used about the city of Cara-
vellas, brought, it is said, from the inland parts of the tidal estuaries,
but taken out at low tide always.

Attention should be directed to the section given at Sao Thomé in
Chapter III. of this report. It will be seen that with the shel] beds is
one stratum that bears a strong resemblance to the snuff-colored beds
found elsewhere. Whether this resemblance means anything I am not
prepared to say. Ordinarily, of course, lithologic similarity cannot be
used to correlate rocks, and least of all over such a wide area as that here
under discussion. But if the Sio Thomé beds are to be correlated with
the other soft sandstones of the coast, either the shell beds at that place
are late Tertiary or the sandstones are more recent than the Tertiary.

As already stated, I am disposed to think that these late sediments
that rest unconformably upon or against Eocene Tertiary or older rocks
are of Pliocene age. If this supposition is correct, the Miocene period
is represented on the coast of Brazil either entirely or in part by the
erosion between the Eocene and the Pliocene, and the land stood con-
siderably higher during Miocene times than it does at present.

Recent deposits. —In the absence of thoroughly trustworthy data by
which the Pliocene beds can be discriminated from the older and newer
sediments, it is evidently difficult to offer much regarding Pleistocene or
recent deposits.

It has always been supposed that the shell beds about the Bay of Bahia
were recent, and no good reason is known for saying that they are

Sey BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

not. But no careful study has ever been made of the shells in these
beds and of their relations to the living shells of the coast, and until
such a study is made the age of the shell beds cannot be considered as
determined. It has always been supposed, too, that the stone reefs of
the coast were recent, but without a comprehensive study of their fossils.
and of the living fauna of the region it cannot be said positively whether
they are recent or Pleistocene or some of them even of Pliocene age.
For this question of the age of the later deposits along the coast is
necessarily closely connected with the question of the ages of both the
stone and coral reefs. If the stone reefs and raised beaches are late Ter-
tiary, then the coral reefs are also Tertiary as well as recent, for the
raised beaches at SAo Thomé, Porto Santo, and about Caravellas contain
fragments of reef-building corals. In any case the later deposits along
the coast are usually shut in the drowned river mouths and lakes, and
in the old choked up embayments described in Chapter V. of this report.
The stone reefs belong with these later deposits.

Conclusions regarding the geology of the coast. — The interiors of all
the states along the coast between Espirito Santo and Rio Grande do
Norte are of old crystalline rocks. Against these old rocks rests a strip of
sedimentary beds that varies considerably in width, and is even entirely
wanting at several points. At the base of the sedimentary series appear
to be isolated Cretaceous basins (and possibly even older ones) over-
lapped by the more widespread Tertiary beds.

The sedimentary rocks of the Bahia basin hitherto regarded as Creta-
ceous appear to embrace more than one terrane. The oldest of these
beds are Cretaceous (or possibly even Jurassic), and above these are
probably Eocene beds, which are in turn overlain by later ones probably
of Pliocene age. The separation of these several terranes cannot be
made without more detailed stratigraphic work. South of Bahia as far
as Abrolhos, and north of Bahia, at least as faras Natal, we seem to have
here and there in the coastal sediments a stratigraphic problem very
similar to that of the Bahia basin, but with less data with which to
solve it: there may be two or more undefined terranes with Cretaceous
below and Eocene Tertiary above, or, if there is but one terrane, we
have in Brazil a faunal combination unlike any known in other parts of
the world.

The brilliant colors of the coastal sediments have been produced by
weathering ; they affect beds of different ages and to varying depths, and
cannot, therefore, be used to determine the ages of the rocks. At many
places these beds are somewhat folded, but the weathering has so affected

BRANNER: THE STONE REEFS OF BRAZIL. 33

them as to give them the appearance, as seen from the ocean, of being
horizontal.

At low elevations there are at many places a series of sediments newer
than, and resting unconformably against, the eroded Eocene rocks.
These beds have yielded no fossils, with the possible exception of certain
ones near Sao Thomé on the Bay of Bahia. They are here tentatively
referred to the Pliocene. The break between the Eocene and Pliocene
is thus referred with doubt to the Miocene period. This would make
the stone reefs of the coast of Brazil a part of the Pliocene, or possibly
of Pleistocene and recent age. Doubts regarding the exact ages of the
Tertiary and recent deposits can be removed only by a more careful
search for fossils and a study of the fossils and of the living fauna of the
coast.

The sequence of geologic events in the history of the coast since and
including Cretaceous time was apparently as follows : —

EVENT. TIME.

1. The deposition of the Cretaceous sediments during a og

sion of the coast . . . . Cretaceous.
2. Deposition of the Eocene Hiestiagy eamieite in Fhe ocean and

in fresh water lakes near the coast . . . . . =. =. . +. Eocene.
3. Elevation, and erosion of land surface . . . say. #t° Mocene:
4. Depression and deposition of the Pliocene sedivnenits . » «+ Pliocene.
5. Slight elevation of the coast; erosion Pleistocene
6. Slight depression of the coast to
7. Elevation amounting to about two metres Recent.

VOL. XLIV 3

34 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

ab GE

Detailed Descriptions of the Sandstone Reefs.

PAGE PAGE
@eara ane 5 on. eae Bod Cabo Santo Agostinho . ... fi
Rio Grande a Nore sgt Ae ROO Porto-de)Gallinhast =) ane een
Pirangy 93. Pee es eee 4), Cacimba and Serinhaem .. . 79
Cunhahit and Sihanmra as oe AO SantorAlerxo 5s iaercaee Ee meaOO
EREALCAO? ee) Se ae Gah Stet ter ie eee Rio Formoso-* 3. 2 "ce eae Oe
Mamanguape . sts hye Slice eee aT Rio Sapucahy_ <: Soe ae oe
Parahyba do Norte ee psa hao Pratagy cscs “ac eee OL
edratde (Gale = =. out OO Bahia: <> )a: 2-5 2 ie eee hoe
TRIO OCe sey ase eee ee OS, SantaC@raz.5 5 bee ee
Pernambuco cc eee ae OD Porto Seguro. . +o We
Piedades 2.9 2-25 see. ae eel Notes upon little- Engen eee 5 EY
Viendap Grande a8. 5) ee OO Miscellaneous localities . . . 101
Gaibtis 4 5, ey eee CO

The Ceara stone reef.—I1 have seen the Ceara reef, but have never
made a personal examination of it. The following notes are taken from
Sir John Hawkshaw,! who examined this port in 1875.

Ceara is in 3° 43’ south latitude, 38° 33’ west of Greenwich. Mucu-
ripe Point spoken of is “about seven Kilometres to the eastward.” Mucu-
ripe Point consists of sandstone rock, and is covered on shore with sand
hills, but the low underlying rocks extend half a mile seaward at low
water. ‘‘Mucuripe Point gives the roadstead of Ceara the appearance of
a bay, .. . but the rocks project too little seaward and lie at too low a
level to afford perfect shelter to the more distant anchorage at Ceard.
There are more rocky shoals west of Mucuripe Point, with deep water
between them, such as Meirelles reef, the Estrella Bank, the Velha reef,
and the Corda Grande shoal. . . . The Recife do Porto, a reef of sand-
stone stretching out in a diagonal direction from the shore at the east
end of the town, is incorrectly shown on most of the charts. It gives
some amount of protection at low water to lighters and small craft, but
as the waves always wash over it except at low water equinoctial spring
tides, this protection is very insufficient.”

1 Melhoramento dos Portos do Brazil. Relatorio de Sir John Hawkshaw.
p. 89-91. Rio de Janeiro, 1875.

BRANNER: THE STONE REEFS OF BRAZIL. 3D

He notes that a soft conglomerate is found in the bottom of the harbor
behind the reef.

Borings were made on the reef showing the rock to be not much more
than a metre thick. It is said that there was formed a channel between
the reef and the shore.

The stone reef at Rio Grande do Norte. — The immediate shores about
the mouth of the Rio Grande do Norte are covered far and wide with
shifting sands. Southeast of the city these sands are being blown
over the hills and into the river to such an extent as to threaten to
destroy the navigability of the stream between the city of Natal and the
bar. Behind these dunes mangrove swamps spread out across the mud
flats that follow the river as far up as the tides are felt.

The topography of the region is beautifully seen from kilometre 3 of the
Natal a Nova Cruz Railway. From this point one looks down upon a
broad flat valley where water merges into mangrove swamp and swamp
into flat dry lands, all ending abruptly against the sedimentary hills to
the north. This flat country continues westward up the estuary of the
Jundiahy to the town of Macahyba, everywhere the same as far as the
general features are concerned.

In the city of Natal itself the same topographic relations are visible
in the open square in front of the railway station.

Fic. 12. Section from Natal to the Stone Reef.

It is worthy of note that the reef is on a level with the mangrove
swamps, and but slightly below the level of the land upon which the
lower city stands. The Tertiary hills on which the upper part of the
city stands plunge as abruptly beneath the flat land at their base as if
that land were a water surface.

The Natal or Rio Grande do Norte stone reef connects with the shore
at its southern end, while its northern end stands squarely across the
mouth of the Potengui, or Rio Grande, so that the water of that stream
flows round the north end of the reef to escape to the sea. The length
of the reef from its northern end at the bar to where it joins the land
is fifteen hundred metres; its length from where it joins the land to its
southern extremity is three kilometres, making a total length of four

36 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY.

and_a half kilometres for the entire reef visible above water. North of
the bar the surf breaks upon the concealed continuation of the reef in
that direction. These breakers lie in the axis of the main reef.

The various breaks and topographic relations of the reef are shown on
the accompanying map made by my assistant, Mr. C. E. Gilman, and
need not be verbally described. It will be seen that this reef is nearly
straight. In width it varies from twenty to seventy-five metres.

On that part of the reef that stands out from the land across the
mouth of the river, and about six hundred metres south of the bar, is
an old fortress now surmounted by a lighthouse.

Seen from a distance the surface appears almost perfectly flat. It
slopes gently toward the sea, but the bedding of the reef rock has a
somewhat steeper though still a gentle slope. In detail the surface is
in some places flat, in others it is etched in a manner characteristic of
all the sandstone reefs, and well illustrated in the photograph of the
etched surface of the Mamanguape reef. This etching is caused by the
removal of certain portions of the upper beds of the rock, and the leav-
ing behind of other and more resisting parts which stand out upon the
surface as sharp points or irregular slabs supported by short columns.
These jagged points are usually from a few centimetres to three decime-
tres high, but sometimes they are a metre high and make it difficult to
walk over the surface.

Where the reef is broken and the surface has fallen in so as to be
lower than the general level, it is uncovered but little as compared with
the higher parts, and here the surface of the fallen blocks is overgrown
with barnacles and is black with seaweeds and corallines and is some-
times bored by sea-urchins.

Along the outer or seaward face the reef is more or less protected
from the force of the waves by enormous slabs that have been dropped
where they now lie by the undermining of the original reef by the sea.
These slabs lie tipped about at various angles, but generally with their
outer ends dipping abruptly beneath the sea, and thus forming an
effective breakwater against the onslaught of the surf. Here and there
the outer face is broken off abruptly. The entire seaward face of the
reef is covered with corallines and other Algae, while the somewhat
protected parts are furrowed and bored by sea-urchins. The cavities
over this outer face of the reef and the seaweeds that grow there abound
in the forms of marine life that generally inhabit such places.

The inner or landward face of the reef along its southern end lies
against the land, or rather the sands of the shore come down upon and

BRANNER: THE

STONE REEF

AT THE MOUTH OF

KILOMETERS

STONE REEFS OF BRAZIL.

ORTE

So r)
#1 ATLANTIC OCEAN.

oC)

cs |

MUSEUM OF COMPARATIVE ZOOLOGY.

BULLETIN

38

In the main the relations of the shore sands

to the reef are concealed.

over its landward edge.

From where the reef leaves the shore and

‘ydvasojoyd & wo

‘YyNoOs 9} WOIJ Udas 9

ON

Op epuRAy) OLY JB Jed OUOJSpUg “FI “org

broken

1s

ces

has water on both sides of it, the landward face in some pla

off squarely, in others it slopes down gently in steps only a few centi-

metres high to low-water level.

BRANNER: THE STONE REEFS OF BRAZIL. 39

In contrast with the outer face there are but few big blocks along the
inner face of the reef, and these are but slightly removed from their
original positions. The depth of the water close to the reef along much
of its inner face shows it to be a steep-faced wall, in places five metres
or more in height.

To the landward of this main reef are to be seen here and there,
especially at low water, portions of an inner, subordinate, and somewhat
lower stone reef. This inner reef is approximately parallel with the
outer one, in some places uniting with it, in others drawing away from
it. The rock of this subordinate reef is the same as that of the larger
reef, but as arule not so hard. From a point fifty-five metres south of
the fort this inner reef runs southward parallel with the outer one, and
from eighty to ninety-five metres away from it, for a distance of a kilo-
metre. As compared with the main reef, this one is rather narrow,
being only from nine to thirty-five metres wide. Along this southern
end the inner reef is so low that it is all covered by ordinary high tides.

Fig. 15. Section across the stone reef, Natal.

At the fort the outer and inner reefs unite, and it is on the broad part
formed by this junction that the fort is built. North of the fort again
the two reefs no longer appear as one. ‘The inner reef here apparently
comes to an end, and the only remnant of it visible is on the northern
side of the river and opposite the bar, where it forms a breaker uncovered
at low tide.

Much of the surface of the whole reef is so covered with Algae, coral-
lines, barnacles, and polyps that the nature of the rock is not apparent.
In some places again the rock is bare, and large sand grains, pebbles, and
shells may be seen protruding on the surface. Everywhere the freshly
broken rock shows it to be a hard sandstone, so hard in fact that the
quartz grains and pebbles often break squarely across, and the fresh
fracture glistens very like that of a quartzite. Loose slabs and project-
ing points of the rock often ring under the hammer like clinkstone.

One of the most striking characteristics of this rock is the fresh
appearance of the fossil shells it contains in abundance. These shells
are apparently the same as those found living upon the adjacent beaches
and sandbars.

40) BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

The Pirangy rock reef. — At Pirangy, south of Rio Grande do Norte,
is the next reef that attracts attention. This reef does not, however,
belong in the same category as the sandstone reefs of the Brazilian
coast, neither is it a coral reef. It is mentioned here chiefly for the
purpose of calling attention to a kind of reefs which are found occa-
sionally on this coast and which are liable to be mistaken for either
sandstone or coral reefs. The accompanying map shows the position
and form of the Pirangy reef. It is, however, only the more resisting
parts of the Tertiary (?) rocks that form the mainland in the vicinity.

The stone reefs of the Cunhahi and Sibatma. — The Rio Cunhahu in
the State of Rio Grande do Norte enters the ocean sixty-seven kilo-
metres (in a line) south of the Natal lighthouse, and nine kilometres
north of Cape Bacopary. It descends through a wide-mouthed, flat-
bottomed valley that extends from Bahia Formosa to the hills immedi-
ately north of the river, ——a distance of seven kilometres. The hills
south of the valley are put down on the hydrographic charts as being
ninety metres high, and those on the north as being one hundred
metres. A single isolated, round-topped hill stands out in the middle
of this valley south of the river. It is shown in Plate 22 on the right.

This valley is a large and a long one, and retains these characteristics
in the main for many kilometres, even above where it is crossed by the
Natal and Nova Cruz Railway.

The immediate shores between Bahia Formosa and the mouth of the
river are covered with sand dunes almost the entire distance. These
dunes are at least fifteen metres high (a. t.), and on the west side their
sands fall upon the sandy soil of a caatinga forest. On the oceanward
side there are exposed beneath these dunes beds of snuff-colored to
black false-bedded sandstones. These dark sandstones are in places
frora two to four metres thick, and lie unconformably against the red
and mottled Tertiary (?) beds exposed at Bahia Formosa. The contact
between these two series of rocks was not seen, but both sets of beds
‘are horizontal, and the dark beds of a later age do not appear in the
beautifully exposed Bahia Formosa section as they would do if they
formed a part of it.

Here and there springs of amber-colored fresh water emerge beneath
these dunes and upon the surface of the dark sandstones. At one place
a large spring comes from the sandstone itself. In places the snuff-
colored beds are below high-water level; in others they are somewhat
higher. The geological relations of the beds are shown in the cut on
page 28.

i.
Fie. 16. (See page 40.)

RIO SIBAUMA.

STONE REEFS

OF THE

RIOS CUNHAHU AND SIBAUMA,|-: }

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CEGILMAN

CUNHAHY.~ |

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are : i -: i,
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= ’ FDA :
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Wits: NES
; f

North of the Cunhahuti there is only
a narrow flat strip of land, barely wide
enough for the houses of the village,
between the river and the Tertiary (?)
hills to the north.

Where the reef north of the river
laps back upon the beach the Ter-
tiary (2) hills are from one hundred and
fifty to two hundred and fifty metres
west of it; and this is as near as the
reefs and the Tertiary (?) sediments ap-
pear to approach each other. North of
this point the reef lies along the beach
all the way to its northern end, while
the Tertiary (?) hills draw off to the
west and swing up the valley of the
Sibatima, and the belt of sand dunes
widens across the mouth of the Si-
bauma valley.

North of the Rio Sibatima the sand
dunes lie between the beach and the
Tertiary (?) bluffs for half a kilometre,
but here the colored beds are exposed
on the beach, and the highest tides
come within three metres of the base
of the bluff. From this point north-
ward the beach is close to and parallel
with the Tertiary bluffs which continue
to and beyond Moleque Point and Ponta
do Pipa. These hills average about
twenty metres high along their faces —
near the shore ; inland they are higher.

The Cunhaht and Sibatima reefs —
originally one reef — have their south-
ern end on the beach 2.7 kilometres
south of the mouth of the Rio Cun-
hahi. This southernmost section is the
inner reef of the two, and has a total
length of eight hundred and seventy-
five metres. It is nearly flat on top,
but structurally it has a gentle sea-
ward dip. The rock is rather soft, but
otherwise it is like the ordinary reef
rock. ;

This inner reef is, however, only a
patchy one. The only other signs of
it are immediately south of the mouth

BRANNER:

of the Cunhaht river,
where several fragments
are exposed at low tide.

The total length of
the outer reef, including
the Sibatima end of it,
and making no allowance
for breaks and bars, is
8.4 kilometres. It is
possible, however, that
the whole of the north-
ern end was not seen, as
the tide was high when
this part of the coast
was reached.

The pieces that form
the southern end of the
reef were not inspected,
but observations were
confined to the portions
accessible from the
beach at low tide. These
portions, however, form
the great bulk of the
reef. South of the bar
the outer reef has so pro-
tected the embayment
that the water is very
shallow, and at low tide
one can walk out to and
beyond the fragments of
the inner reef then ex-
posed. The sand flats
between the land and
the reef contain many
mollusks similar to those
whose skeletons are
found in the reef rocks.

Just north of the Cun-
haha bar the reef is
twenty metres wide.
This portion of it grad-
ually approaches the

THE STONE REEFS OF BRAZIL.

z

RENAUD

43

From photographs taken at low tide.

Ripple-marked sands on the landward side of the Cunhahii sandstone reef.

Fig. 18,

44 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

beach and finally merges into it. It appears to be perfectly straight ;
the slight curves of the entire reef are brought out only when one can
get a view of it from some high point from which he can see lengthwise
of it, or by a survey on a large scale.

The landward face of the reef is in places broken square off, but for
the most part it slopes down rather abruptly but not at right angles.
The outer face is in most places broken squarely off.

The top is flat, covered with small shallow pools, especially on the
outside, and with low etched points studding the inner or landward
margin.

The rock of the reef is like that of most of these northern stone reefs,
—a light-brown sandstone of medium fineness, and varying slightly
from place to place in hardness, coarseness, and the abundance of fossil
shells. It contains many pebbles made of the red or black iron-stained
sandstone so common in and characteristic of the Tertiary beds of the
vicinity. It has also the usual fossil shells, though they are probably
not so abundant as they are in some of the other reefs.

The sand-covered flat behind the reef is flooded at high tide; when
the tide is out many big angular fragments of the reef rock are un-
covered and left projecting from the sand. I did not see on top of this
reef any loose blocks thrown up and left by the surf. The surf outside,
however, is very severe at times, for there are no outside coral reefs
to break the full force of the waves coming in from the deep ocean.
I am disposed to think that the angular blocks partly buried in the
sands behind the reef are pieces broken by the surf from the outer face
and thrown completely across it.

A topographic peculiarity often seen in connection with the stone
reefs that lie on or near the beach is well illustrated at several points
along the northern end of the Cunhahi-Sibatima reefs: where these
inshore or beach reefs are broken clear through the sea is able to
encroach upon the land, but only to a limited extent. The result is
that semicircular bays of sizes proportional to the width of the open-
ings are cut in these shores. A similar bay at Gaibi is illustrated at
page 70. .

The rocks of the southern end of the inner reef are covered with great
quantities of a sandstone of organic origin, —a kind of rock I have seen
only on this northern coast of Brazil. These rocks are formed by worms
that cement together sand grains in masses resembling sandstone boulders.
They appear always to be built upon hard rock bases.

The material is not hard where found on the beaches, but can be

BRANNER: THE STONE REEFS OF BRAZIL. 45

readily dug into with the sharp end of a geological hammer. Excellent
examples cover much of the beach just north of Bahia Formosa, where
the views reproduced in the plates were taken.

The examples mentioned as having been observed at the south end
of the Cunhahu reef are the only ones seen upon a stone reef.

The Traicdo stone reef. — The Traig&o reef lies in front of the Bahia
de Traigio in the State of Parahyba. This and the Mamanguape reef
to the south of it really form, or rather they appear once to have
formed, one single and continuous reef, and to have been separated by
the breaking down of what may now be called the southern end of the
Traigao reef.

The topographic features of the country back of the Traig&o reef are
of rather more than usual interest, and what is said here upon this sub-
ject, in so far as it bears upon the origin, form, and history of this reef,
is equally applicable to the Mamanguape reef.

To the west is a table-land of Tertiary sediments from twenty to
forty metres high, of pretty even elevation and sky-line, but notched
here and there by streams. This plateau, where it comes down to form
the coast bluffs north of Traic&o, is shown in Plates 29 b and 30.

The sky-line at this place is noticeably less even than it is further
south along this coast; the field notes on the locality remark that north
of this place outlines of the coast hills have the appearance of sand hav-
ing been blown over them. Where Plate 30 was taken the bluffs end
abruptly as beach bluffs, and, swinging westward and northward with
somewhat gentler slopes, pass along the east side of a long narrow
marsh (for several kilometres, I was told), then return southward along
the west side of this same marsh or lake and continue nearly due south
until they approach near the Rio Mamanguape. Here the river makes
a wide gap through these hills, but south of the stream they come to
an end as inland hills at the Miricf red bluffs at the south end of the
Mamanguape reef.

West of the village of Traica&o the church of Sao Miguel dos Milagres
stands on the top and edge of this Tertiary plateau. Between the
bluffs of Sao Miguel and the town of Traig&o the hydrographic chart
shows a lake, known here as Lagéa de Sinimbi.'' By courtesy it may pass
as a lake, but strictly speaking it is little else thau a fresh-water marsh
with a sluggish stream flowing through it.

The Lagéa de Sinimbit is separated from the ocean by a low bank of

1 The name given on the chart may have been its name formerly, but it is now
called Sinimbu.

46 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

sand which everywhere has the appearance of having been blown up
from_the beach. In places this sand ridge is scarcely high enough to
keep the spring tides from flowing over it into the lake, but at one place
south of the village it has a height of nine metres on the seaward side.
From the village northward to the base of the hill on which the old fort
stands this ridge is only from sixty to one hundred and twenty metres
wide from fresh water to highest tide-level on the seaside. South of the
village it widens out somewhat, and at one place is two hundred metres
wide. The drainage of the lake is thus compelled to seek an outlet
through the Rio Mamanguape, ten kilometres south of the low narrow
neck north of Traic&o.

Plate 30 shows this neck of sand with the bay to the right and the
marsh of Lagéda de Sinimbt on the left.

A line of levels run across this neck shows that the lake water on July
24, 1899, was fifty-nine centimetres lower than the level pointed out as
that of the highest spring tides on the sea beach. The mean tide-
level, however, is a metre or more lower than the lake surface.

The Lagoa de Sinimbi and the flat lands about it and about the
mouth of the Mamanguape lie as one broad flat region bebind the reefs
of Traigio and Mamanguape alike. For a fuller discussion of these
geographic features and their history and bearing upon the reefs the
reader is referred to Chapter V., pp. 111 to 170.

The Traic&o end of the reef ends rather abruptly, standing boldly out
to sea. At low tide one can walk dry-shod from Traicio Point out on the
stone reef, so that it may be said to join the land at that place. South of
Traicao Point the land draws away from the reef, forming thus the north-
ern part of Mamanguape Bay, while north of the point the land swings
away still more sharply to form the Bahia de Traig&éo. A good view of
the bay is had from the site of the old abandoned fort north of the town ;
from this point the photographs for Plates 29a and 29 b were taken.

The Traig&io reef has a total length of only a little more than two
kilometres ; this does not include the fragments or outliers that connect
this with the Mamanguape reef. Those fragments alone down to the
bar have a total length of 2.4 kilometres.

A glance at the map shows that Traigio reef has a gentle outward
curve at Traicéo Point. It is rather broken, and its outer edge is
ragged. In several places the waves are undermining it from the out-
side. On the whole it is a flat and rather smooth reef. Along the
inner margin are the usual points left by surface etching, but they are
not so high or so prominent a feature of this as of the Mamanguape

reef. Over the surface are
the customary tide-pools,
though but few of them
have any considerable depth.
These pools lie mostly along
lines parallel with the main
axis of the reef. Much of
the surface is covered with
light green seaweeds.

The rock of the reef is a
hard sandstone of a light
brown color and contains
many fossil shells.

The Traicfio reef, perhaps,
more than any other one ex-
amined shows the effects of
the wear and tear of the
surf. Inside the reef there
are many blocks buried in
the sands, apparently broken
from the outer face and
thrown across by the waves ;
the outer edge is decidedly
serrate, seldom presenting a
bold face to the sea. Here
and there the waves have
opened beneath the reef great
caverns in which they can be
heard to swash back and
forth. Sometimes these
waves can be felt to jar the
whole reef surface over an
area of several hundred
square metres.

For details of other charac-
teristics of this reef reference
is made to the description of
that of the Mamanguape.

The Mamanguape stone
reef.— The Mamanguape
reef is one of the largest and
most impressive of the stone
reefs of Brazil. It is here
described as a separate reef,
but properly speaking it is
continuous with the Traigado
reef to the north of it, and

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48 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

from which it is separated by only a few small breaks. At the south
end also it continues far beyond the limits shown upon the accom-
panying map, so that, long as it is represented, its total length is not
really known, and neither are its geologic and geographic relations
about its southern end.

The Rio Mamanguape, a stream that drains a large area in Parahyba
do Norte and in Rio Grande do Norte, flows down behind the reef and
debouches both right and left through breaks or small bars, none of
which lies in front of the river proper. The southern channel where it
flows between the outer and inner reef is only about one hundred metres
wide, but the channel is deep and the current is strong.

The country landward is all flat and low back several kilometres to
the base of the hills or table-lands that skirt all this northern coast.
The bay itself is mostly quite shallow, and at low tide looks like a
series of sand banks and shallow ponds. In the deep water of this bay
the dredge brought up only sand and fragments of broken shells.

The northern end of the reef that lies south of the Barra do Maman-
guape is a single, flat, and nearly straight reef down to a point shown on
the map, one and a half kilometres south of the bar, where it has the
appearance of branching. Here a smaller and lower reef puts off from the
main one and runs parallel with it and at a distance of about one hundred
metres from it, until after several large breaks it joins the beach west
of the river at Mamanguape Point. This inner reef is really a lower
bed or beds of the main or outer reef. Where the two separate the
inner one can be seen to dip gently beneath the great outer one. The
junction of the two is fairly well shown in Plate 34. It is noticeable
that while the lower reef is comparatively strong at this junction, it
weakens southward as it separates from the larger one. The rock of
the inner reef isof the same kind as that of the outer, save that it is not
so hard.

At high tide (flood tide, June 23, 1899) the big reef was only 0.45 to
0.61 metres out of water at some of its highest points, while the surf
broke over all of it save where isolated loose blocks have been piled on
top of it. At low tide it stands from 2.1 to 2.4 metres out of water.

Considered lengthwise, there is but little difference in the level of the
top of the reef, — perhaps not as much as one metre in its entire length,
breaks excepted. Here and there it has been undermined, and the sur-
face rocks of harder stone have been Jet down in these gaps and are
now covered with barnacles, seaweeds, and the like. These breaks are
of various sizes, from those that one can walk across at low tide to those

BRANNER: THE STONE REEFS OF BRAZIL. 49

barely large enough for jangadas to pass through. The breaks are
most abundant south of Mamanguape Point where the outflowing river
strikes it. Several of the minor breaks, even at the lowest tides, have
the water flowing through them between and beneath the loose blocks
that fill them.

Strictly speaking, the reef as a whole is not straight, but neither is it
very crooked. The bends in it are quite apparent when one sees the
reef itself, but on a map of small scale they hardly appear. These
curves are such as one may see on any approximately straight beach.

Considered in cross-section, the surface as seen from the bar has a
gentle slope seaward. In most places the landward face is abrupt, and
the channel of the Mamanguape River passes close up against the reef-
wall. Toward the southern end, however, and especially where the
inner face has been protected by the secondary reef, the profile comes
down at a gentler angle or by a series of small steps or low terraces.

Fic, 20. Section across the Mamanguape stone reef.

The outer edge of the reef is here and there broken off with beauti-
fully smooth vertical faces. But even in such cases it is protected to a
great extent by its own fragments, many or most of which are gigantic
blocks undermined on the seaward side and let down to where they now
lie. Toa notable extent these blocks lie at angles that make them most
effective protective agents for the rest of the reef, and least liable to in-
jury themselves from the onslaught of the sea. The following examples
(Fig. 21) are types of the fractures observed on these faces.

In all these cases the sea is to the right and the reef to the left. It
is noticeable in these instances that the broken fragments have the
appearance of having been let down by undermining, and they now lie
so as to serve as effective protection to the remainder of the reef,
whether from undermining or surface wear. Many cases were observed,
however, in which the fragments lie altogether at haphazard.

Some sheer faces more than three metres high are openly exposed to
a tremendous surf apparently without being in the least affected by it.
At one place there is such a face sixty-five metres in length. Now and
then one may observe, when the surf is powerful, that the shock or jar
of the blows is very marked over a given area. I take it that these

VOL. XLIV. 4

50 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

places will eventually give way and form gaps or barretas in the

reef.

That the surf has upon occasion been able to break off large blocks
from the reef is shown by those now found lying loose on the surface at

Fie. 21. Characteristic breaks of the
outer edge of the Mamanguape
stone reef.

several places. One of these blocks is
estimated (at one hundred and sixty
pounds to the cubic foot—a low esti-
mate) to weigh not less than nineteen
tons. Another weighs five tons, and
still another weighs twenty-two tons.
This last one has been swept over
and across the reef and now lies close
to its inner edge. The five-ton block .
has its upper surface striated and pol-
ished very much as if it had been
glaciated. This has been produced
by its having been pushed gradually
by repeated blows across the reef;
when near the inner margin it was
turned completely over and _ left
where it now lies.

At another place north of the fork
in the reef there are thirteen blocks
or slabs, some of them weighing sey-
eral tons, lying on top near the inner
margin and within a distance of a
hundred metres. Some of these pieces
show by the position of the fossil
shells they contain that they have
been inverted by the waves.!

The rock of the reef is a slightly
yellowish, rather coarse, but remark-
ably fresh-looking sandstone. In
places it contains beds of pebbles,
but these beds are neither thick nor
wide-spread. Near the middle of the

reef there is exposed on the surface a bed of quartz pebbles many of

1 The majority of separated bivalve shells lie on a beach in such a position as
to offer the least resistance to the water passing over them; that is, with the con-

vex side upward.

BRANNER: THE STONE REEFS OF BRAZIL. 51

which are larger than one’s fist. Mingled with the quartz are also, both
here and elsewhere over the reef’s surface, large pebbles of dark red
Cretaceous or Tertiary sandstone such as occurs in the hills that skirt
this coast. There are also occasional patches and lumps of a very black,
compact, heavy rock made up of grains of titaniferous iron. At one place
near Mamanguape Point a piece of this black iron rock, 4! x 4! x 5", was
found on top of the reef cemented compactly to an underlying bed or
coarse white sand and pebbles. This rock is as black as coal, is com-
posed of particles of black titaniferous iron sand, and shows false bed-
ding. <A few other blocks of similar material, one foot square, are near
this one and attached in a similar fashion. Half a mile further south
angular and subangular fragments of this rock the size of the two fists
and some as big as one’s head are buried in the sugar-brown rock of the
reef, forming a sort of breccia for fifteen metres or more. At many other
places this material occurs as pebbles scattered through the brown reef
rock. These spots are caused by the concentration of titaniferous iron
sands upon the ancient beaches. They are cemented by carbonate of
lime and magnesia in the same manner as the other reef rock.

The most characteristic thing about the rock of this and of all the
other stone reefs is the presence in them of fossil shells of various mol-
lusks now living along the coast. These shells are not evenly distributed
through the rock, but are abundant in some layers and almost or quite
wanting in others. Most abundant of all is a small, beautifully varie-
gated, thick-shelled Venus known here as mariscos. These shells still
retain in the rock their brilliant colors. The shells are never found in
pairs as in life, but broken apart and with the horny cuticle they have
when alive worn off. During their lives these marzscos burrow in the
sand of sandbars and protected sandy beaches to a depth of about two
inches. They are edible, and are used for food more or less all along
the coast.

In one of the blocks near the northern fourth of this reef was found
also a block of Porites, one of the hardy corals now growing upon the
coral reefs and in the rocky tide-pools of the coast.

The reef rock proper when found in large slabs or projecting points
rings under the hammer almost like bell-metal. It is, however, not
everywhere equally hard: the upper beds, especially those exposed now
and then to the sun and atmosphere, are as a rule hard and even
quartzitic in fracture, while in other places the same beds may be
rather soft and incoherent.

The surface features of the reef are not without interest. Here and

‘
52 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY.

there it is as flat and smooth as any sandstone slab for hundreds of
metres; again it is so rough and uneven that it is almost impossible to
walk over it. Over much of the surface there are shallow depressions
that look like gigantic footprints made by mud-clogged feet in thick
mud. At such places the surface of the reef has a profile like this:

Fic. 22. Section across the Mamanguape stone reef.

In plan these pits have these and similar forms (Fig. 23) :

These pits are from three to seven
centimetres deep and from a few centi-
metres to two metres long. For the
most part they are parallel, but some-
times they stand at various angles to
each other.

The Mamanguape reef has some fine
ia. 2) “Roemetcr aheupiaten examples of etched surfaces. One of
surface of the Mamanguape reef. these is shown in Plate 41, a photo-

graph taken near the inner edge of the
reef on its southern half. This etching leaves ragged sharp points that
vary in height from a few centimetres to a metre, and a great number of
fantastic forms.

Fic. 24. Characteristic forms produced by the etching of the Mamanguape
stone reef.

Some of the pillars on the Mamanguape reef are as much as two
metres high; the tall ones are, as a rule, on the landward side of the
reef, — never close to the surf-beaten sea side. These spike-like projec-

BRANNER: THE STONE REEFS OF BRAZIL. 53

tions are invariably of very hard rock that rings under the hammer ;
they make walking over the surface of the reef in certain places almost
impossible. Other points, rounded in outline, but standing at lower
levels, are covered with barnacles.

There are but few places over the surface of the entire reef that have
the rock freshly exposed. On the outer face and wherever kept con-
stantly moistened with salt water, corallines and other Algae grow in
greater or less abundance. Barnacles abound in the gaps and depres-

—— — wm wm mM = ee wm me ae ee eee ee ee eK

q

Fic. 25. Tide-pool formed by organisms
on reef,

sions in those places that do not receive
the full force of the surf and yet are low
enough or so situated as not to be long
out of the water. Young barnacles speck
the reef everywhere. The seaward edge,
where the reef is flat, generally or always
has a little low rim rising as a dam on
its margin and enclosing shallow pools of
water on top of the reef. Fig. 26. Sea-urchin burrows

Oysters are found in patches along the on the surface of a sand-
. : stone reef; plan and sec-
inner face of the reef, especially where tion:
the ebbing tide brings the river water
against it. There are occasional patches of dead oyster shells clinging
to this inner part of the reef.

A large part of the outer surface and much of the top of the reef
where it is kept constantly wet by the surf is full of holes and channels
occupied by sea-urchins. These holes are two or three inches deep and
of various lengths, from a few centimetres to two or three metres.
They show a decided tendency to lie parallel to each other and with the
direction of the waters that wash over them. In section they are under-
cut, as shown in the profile herewith.

These trenches are not full of sea-urchins, but have a few individuals
scattered through them, or, at most, are half full.

54 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

Cracks are common over all the harder parts of the reef. These cracks
run in all directions: some of them are parallel with the main axis of
the reef, some are at right angles to it, many of them are forked, and
some of them curve through an arc of ninety degrees within a distance of
forty metres. These cracks are not open ones as a rule, though some of
them are. Some of them gape broadly to a depth of four to six centi-
metres only.

These cracks look as if they were worn, but I have never been able to
find any evidence of such wearing unless the form itself be accepted as
evidence. At many places the crack has the rock on one side of it five
or six centimetres higher than on the other, much as if the rock were
slightly faulted. It should be added that they are not faults.

Some cracks that would otherwise be open at the surface are closed
by the ingrowing of Serpulae. These cracks are generally deep, but are
only seven centimetres or less in width.

Fic. 27, Sections across typical cracks in a stone reef.

Almost everywhere that the rocks are weathered or unprotected they
show false bedding, and less frequently they exhibit the true bedding.
In Plate 41 the true bedding can be plainly seen.

The tide-pools over the surface of the reef contain fishes, crabs, and
the like. Of the corals only a few forms are found in these pools: most
abundant are Porites and the small heads of Favia.

There are no signs of a coral reef seaward of the Mamanguape sand-
stone reef.

It is unfortunate that I was unable to see the southern end of the
Mamanguape reef and to learn something of its geologic relations there.
It is also to be regretted that the bearing of what could be seen at the
point where the reef approaches nearest the shore at Barra do Maman-
guape is not altogether clear, except as it can be explained by reference
to other places.

As shown on the accompanying map, the great outer reef continues
southward past Mamanguape Point a kilometre or more, bearing south
6° west (magnetic) and parallel with the shore. Immediately west of
the reef, and running against it as if against a wall, is the south-flowing

BRANNER: THE STONE REEFS OF BRAZIL. 55

mouth of the river here a hundred metres wide. West of this branch of
the river is exposed at low tide a portion of the inner reef. This inner
reef is here from ten to eighteen metres wide and three hundred metres
long ; at low tide it connects with and forms part of the beach. The rock
is in places of a reddish color, and is not as hard as that of the outer reef.
Fifty metres west of the inner reef and exposed on the river bank at low
tide is a soft pebbly sandstone, in texture very like the reef rock, but
containing no shells and varying in color from a dark brown to perfectly
black. These black beds underlie Mamanguape Point and are barely
covered at high tide. The Mamanguape Point itself is of white sand to
a depth of eight or nine metres, Keaped up here by the wind, but thin-
ning and disappearing east of the village of Barra do Mamanguape. Be-
neath this sand the black rocks pass westward round the point and up
the river to and beneath the village, above which it is still visible here
and there. These black sandstones are about on a level with the outer
reef. They appear to have been colored by organic matter. In places
they are strongly false bedded. (Compare geology of Rio Formoso.)

The consolidated beaches of Parahyba do Norte. — At the entrance to
the Rio Parahyba do Norte, State of Parahyba do Norte, the great reef
on which the lighthouse stands is of coral. This will be described in the
second part of the present paper. /

Properly speaking, there is no sandstone reef in the vicinity of this
port. The coral reef is only about one kilometre from the shore, with
which it is parallel. From the Ponta da Matta southward for something
more than a mile the beach is low, flat, and sandy, and planted with coco
palms. Beyond this to the south begin to appear evidences of an old
consolidated sand beach, and these signs continue for nearly twelve hun-
dred metres. The beach, however, continues to be sandy, and the pen-
insula west of it is still low and flat. Loose blocks of the sandstone of
the consolidated beach are sparsely scattered over the beach in some
places, and in others the bed is exposed in place. The exposures are all
between high and low water marks, and so far as was seen, are confined
to the beach, where they are generally overlain by a metre or more of
sand and soil.

The peninsula lying between Rio Parahyba and the ocean is narrow-
est one kilometre south of Fortaleza da Barra, and at or very near this
narrowest part the remains of a consolidated beach are uncovered. This
exposure is between the village of Cabedello and the beginning of the
mangrove swamp on the right side of the river, and is nearer the swamp.
The exposure is between high and low tides, the rock not very hard, and

56 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

is composed largely of the sand of calcareous seaweeds of the same species
as those now living on the coral reef outside the barra. The exposure of
recent sandstone here is only about two hundred metres in length, and
the locality is a little to the north of opposite the most northern exposure
of consolidated beach on the ocean side of this neck of land, which is
here seven hundred and seventy metres in width. The peninsula is all
low, flat and sandy or swampy, and there are no hills on the south side
of the Rio Parahyba do Norte until near the city of Parahyba about.
seventeen kilometres up the river.

Something will be said of the physical features of the region about
the mouth of the Rio Parahyba do Norte in the part of this paper treat-
ing of the elevation and depression of the coast.

The Pedra de Galé or Goyanna stone reef. —'The Goyanna stone reef
or reefs lie off the mouth of Rio Goyanna, State of Pernambuco, one part
of it being north and the other south of the Barra de Goyanna. Only
the northern part of this reef was examined.

This northern reef is known to the sailors of the coast and to the peo-
ple of the region as the Pedra de Galé or Recife de Galé.*

The country to the west is hilly (Tertiary) both north and south of
Rio Goyanna, and the river enters the sea through a flat region. The
outstanding point between the hills is a low sandy flat planted with
coco palms, but further west mangrove swamps stretch across the val-
ley. The water landward of the reef is mostly shallow. The dredge
brought up here only sand with a few shell fragments.

The reef is only a short one, is quite isolated, stands well out from the
shore, and ends abruptly without any sign of a submerged continuation
so common with the stone reefs. It is only a few hundred metres long,
and varies in width from 15 to 25 metres. The surface is flat in the
main, but has a gentle seaward slope. The rock is very hard and can be
readily broken only on the projecting points left by etching. The sur-
face is pitted unevenly, but the stone is nowhere bare. In places the
rock is cracked, and great blocks, ten or fifteen metres across, have

1 These reefs are not properly located on the hydrographic chart of this coast.
The northern one is there represented as lying nine miles north of the bar: by
measurement it is about a third of a mile. The southern reef is represented as
being seven miles long. That piece I did not measure, but as we saw it from our
barcaca with the chart before us it did not seem to be nearly so long, even with all
the outlying fragments included. The direction of the axis of the reef with refer-
ence to the land is also incorrect: the entire northern reef is in line with the low
flat land one quarter of a mile west of Ponta de Pedras. Its magnetic bearing is
north 27° east. (June 17, 1899.)

BRANNER: THE STONE REEFS OF BRAZIL. 57

dropped a little as if undermined and let down in place right in the
body of the reef.

el

x

Fic. 28. Pedra de Galé reef. From a photograph taken at low tide.

Both on the outside or seaward face and on the inside square-faced
blocks have broken off and been let down at various angles.
Barnacles cover much of the surface. In the surface tide-pools Porites

i taal aamamaaiaiaiaaiaaiaaia miles as iain ee 5) Aaa a ea
]

‘apy sey ye uoyez ydvasojoyd v woig “food aUOJspues a[VH 9p BVAPEg “GZ ‘DLT

BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

58

BRANNER: THE STONE REEFS OF BRAZIL. 59

and Favia grow sparingly, and
crabs, sea-urchins, and small
fishes are abundant. The
quieter waters on the landward
side of the reef contain great
patches of brown polyps and
some small heads of Porites.
The outer or seaward side of
the reef is covered with polyps,
corallines and other Algae.

The Rio Doce stone reef. —
The Rio Doce is a small stream
entering the sea 7.4 kilometres
north of the Olinda lighthouse.
From Olinda northward the Ter-
tiary hills swing inland, and,
keeping more or less parallel
with the coast, approach the sea
again only on the north side of
Rio Maria Farinha." oy]

From one of the valleys cut C.E.GILMAN. Wy ji
across this Tertiary plateau and a

! Seale.

across the intervening flat coun-

try flows the Rio Doce. Along
the beach both north and south
of the river’s mouth is a long
narrow bank of loose sand from
two to four metres high. Be-
hind this bank the land is lower
and flat, while near the river
it is covered with mangrove
swamps.

Beginning one kilometre south
of the mouth of this river is a

S:
aah)

1000"

1 The hydrographic chart is at
fault here in not showing the hills
at Maria Farinha just north of the
river. Besides, there are no such
railways as those shown on chart
1503 running from Goyanna nearly
to Olinda.

Fig. 30,

60 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

stone reef* extending southward along, partly upon, and partly off the
beach, and having a total length of 3.3 kilometres. This includes also
the fragments on the beach at its southern end. As will be seen from
the map, the reef is more or less broken throughout, the longest piece
being only fifty-three metres long.

It is fifteen metres wide at its widest part above water, but it dips
gently seaward, and its total width is considerably more than this. It
is Mr. Gilman’s opinion that the largest pieces have a width to the east
of about one hundred metres more than is shown upon the map.

The entire surface of this reef is thickly covered with corallines and
barnacles.

At the southernmost point on the beach is an exposure of rock similar
to that of the reef, and like it containing many shells and some pebbles,
and strongly false bedded. These beach fragments are much etched.

At another place in front of the village and about half a kilometre
south of the northern end of the reef is a similar exposure of sandstone
on the beach three decimetres above tide, and underlying the sandy soil.

On the beach of calcareous sands are many bivalve shells, and similar
shells are imbedded in the rocks of the stone reef.

The Pernambuco? stone reef. — The Pernambuco reef lies in front of a

1 The notes on the Rio Doce reef were kindly made for me by my assistant, Mr.
C.E. Gilman. I have myself seen this reef several times, but many years ago, and
my early notes on it have been lost.

2 The name Pernambuco is variously spelled by the old writers on Brazil: Fer-
nambouc, Fernambuquo, Paranambuquo, Pernambuck, etc. Hans Staden spells it
“Prannenbucke.” Fernandez Gama explains the name thus: “ The native Indians
called the bar Pera Nambuco, that is to say, broken rock or hole, in allusion to the
opening through which the ships enter. . . .” (Memorias Historicas da Provincia
de Pernambuco, Por José Bernardo Fernandez Gama, 1844, I., p. 97.) Macedo gives
the same explanation except that he says the native words are Pera-nabuco (No-
cdes de Corographia do Brazil, por Joaquim Manoel de Macedo, p. 101. Rio de
Janeiro, 1873.) Sir Richard Burton says the etymology is Parand mbok or mbo,
meaning sea-arm. (Hans Stade of Hesse. Hakluyt Soc., 1874, p. 20.)

The fantastic explanations given by Johan Nieuhof, by Arnoldus Montanus,
and by Rolt are quite out of the question. The first derives it from Inferno
enbokko, which he understands to mean the mouth of hell, and to refer to
the harbor mouth. (Gedenkweerdige Brasiliaense Zee-en Lant Reize. Amster-
dam, 1682, p. 13.) Montanus says the word means “mouth of hell.” Rolt ac-
cepts a similar explanation from the Portuguese Jnfernoboco. (A new and accurate
history of South America. By Mr. Rolt. London, 1756, p. 546.)

For the correct explanation of the word see note under “ Rolt” on pages 221 and
222 of this report.

Recife is the name of the older part of the city lying east of the Capibaribe.
This word is simply the Portuguese for “ reef,” and is originally from the Arabic,
— not from the Latin recipere, as stated by Barleus. (p. 66.)

SD ee ik as

‘pus YINOs oy} vou uoyuy Ydvasojoyd vw woay ‘Joos OonquivuIag ‘Te ‘OTT

a>

\f ay 4
“~ aes 2 a
Nspe Te,
eS 3y 3
Re

62 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

low flat country. At Olinda, about five kilometres north of the city of
Recife, the high lands reach the sea. The high hills swing inland from
this place to Caxanga and approach the coast again near the town of
Cabo, north of Cape Santo Agostinho. The flat country west of Per-
nambuco is a recent deposit, and a comparison of maps made during the
Dutch occupancy during the first half of the seventeenth century (1630-
1644) with the present features shows that the filling up of the old
marshes and estuaries is still going on. Two streams, the Beberibe and
the Capibaribe, flow across these low lands and enter the sea in the rear
of the stone reef. These streams are not large enough for navigation
except by canoes and other small boats. The tide ascends the Capibaribe
twelve kilometres. From the high land at Olinda a sand spit extends
southward, forming the shore and separating the ocean and Rio Beberibe
for a distance of four and a half kilometres, to the mouth of the Capibaribe.
The city of Recife stands on the southern end of this spit.

The channel between the Recife spit and the sandstone reef is two
hundred metres wide in its narrowest part, while further south it
branches to a width of nearly one kilometre. The narrow channel
between the lighthouse and the mouth of the Capibaribe is deepest and
forms the harbor of Pernambuco. In the broader portions the channel
is considerably shallower. Five kilometres south of the lighthouse that
stands on the north end of the reef the mainland at the Ilha do
Nogueira is only three hundred metres from the reef. The reef from
its northern to its southern end, a distance of six kilometres, is very
nearly straight, and is unbroken save at one point, the barreta, where
there is an opening wide enough to permit the passage of jangadas and
such small crafts. At the north end of the reef it seems to be con-
tinued in the same direction by a submerged reef about six hundred
metres long. Beyond this its course is not distinctly traceable by
shoals. At the southern end the reef breaks down gradually, and its
southward extension is only suggested by a few submerged isolated
breakers lying in the axis of the main reef. There is no apparent
difference between the appearance of the reef to-day and its appear-
ance during the Dutch occupancy, as shown by the old prints made
in 1645.

Seen from the sea the reef looks like a long, low, artificial breakwater
of even surface and with a straight but ragged outer margin. This outer
surface is overgrown with corallines and other seaweeds, Serpulae, polyps,
barnacles, ete., and is also bored into by sea-nrchins. At low tide it is
exposed its whole length like a low black wall.

‘Opl} MOT 7B UayL} Ydvasojzoyd v wos ‘yoot OONQIUBUAI OI} JO VV] AUNT ALT, “Ze “OY

y
~

er ee GA

Ny

64 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

At extreme high tide when the wind is high (neap tide at Pernambuco
is less than one metre ; spring is 2.2 metres), the surf breaks over the
top of the reef almost its entire length, though not with force enough to
disturb the shipping anchored in the narrow harbor behind the reef.

The upper surface is approximately flat, but somewhat rough, owing to
the varying hardness of the rock and its uneven wearing. To protect
the reef, and to prevent the surf from disturbing the shipping inside the
harbor, an artificial stone wall was built during the Dutch occupancy
along the northern end of it.’ In width it varies from twenty to sixty
metres.

The inner or landward face of the reef is slightly irregular, as is shown
in the accompanying illustrations. The scour of the ebbing tides sweeps
out seawards the silts brought down from the land, so that the inner face
of the reef is abrupt, and the water close alongside is usually deep.

The reef rock is composed mostly of siliceous sand grains cemented by
carbonate of lime. It contains besides many shells of such mollusks as
live in the sea along the coast, and more or less calcareous matter from
broken Serpulae tubes, mollusks, gorgonias, and the like. The shells
retain their original bright colors.

The structure of the stone reefs was never certainly known until 1874,
when Sir John Hawkshaw, the English engineer employed by the Bra-
zilian government to report upon the harbors of that country, made a
series of borings upon the Pernambuco reef and in the spit upon which
Recife stands. These borings show that the hard rock is only three or
four metres thick, and that beneath this are beds of sands, clays, marls,
and shells. The deepest boring on the reef was made nearly opposite
the landing-place at Recife, and was seventeen metres in depth. The
record is as follows : —

RecorD OF BORING ON THE PERNAMBUCO REEFS.

METRES.
Reef rock, hard’ *. < . 60 = Sethe: one eee
White sand PPE Germ ee ee
Shelle 9 6 oe he
Gray sand... “6 3 ses Ae
Broken rock |... « ‘ce 6, on 0g eccpeen ie meen eae nna
Dark sand «9. os) se ea eee
Mottled. clay gp <i. c0: 2) 0) ioe, | = ee
Yellow Glay "<6 0+ 5 ©) “ete a |
Gray sands 0. . ene 0
White sand Serre

Journal of a voyage to Brazil, by Maria Graham, London, 1824, p. 101.

wif

‘pud YRAOU OY} Avou uOyZV} Ydvisojoyd v WOT

7 ) aes Bz

: F /,\ f ) Ns = S
a Zaypt Yi] i Eee Wn
NGM 2 Si
“Ly dy, Fy) WE Z

Wy, Hitt NGM,

\
/} Mh | A\! '
Pps Ji\\in Z
ly I! yi) YY Vie
é \))

\

‘Joo OONGUIBUIA,, 94} JO OPIS paRMpuL’T

oy 7A Uy Aah

LEY
Fg

fe

5 ee io We
“HIN Uf Za)
bp i

ee WY

"68 ‘OlA

Mm

U]

=

66

BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

The two other holes bored in the reef, one just below the arsenal, and
the other opposite the custom-house and near the mouth of the river,
show a succession of sands, shells, and clays, but there is apparently no

eee
Te

[

+
|

3 Metres

2

1

BORINGN® Te

7A ST OIZE reef, orl ere.

Shells and
Fer Loase Sfones
Saad
$, Sharp
Si Send
Shells

Rock im
preces

Mottled
Clay

Yellow

_ Cley

Share
White Sand
Shells

Grey Sand

Rockin
pieces

Dark
Sand

Mottled
Clay

Yellow
Clay

Fie. 34. Records and locations of borings made by Sir John Hawkshaw in the

Pernambuco reef.

regular sequence in the order of these beds, as will be seen by the accom-
panying cuts copied from the map forming a part of Sir John Hawkshaw’s (

report.

7 ers

BRANNER: THE STONE REEFS OF BRAZIL. 67

As elsewhere pointed out, I regard the clays found in the lower
portions of these reef sections as evidence of the present beach line,
and of the reef itself having been formed against or deposited upon an
older beach that formerly lay further landward. The clays themselves
are not beach deposits, but are the off-shore equivalents of beach
sands.

That these stone reefs should have withstood the seas that break upon
and over them, especially during heavy southeast gales, is one of the
remarkable things about them, and especially so when we remember
that only the upper part of the reef is consolidated. It is worthy of
note also that when the reef is broken up the breaking seems to be due
largely to the attack upon its landward side rather than to the force of
the waves that break upon it from the sea.

At one place the force of the stream discharged into the harbor, and
against the landward face of the Pernambuco reef, probably aided by the
nature of the water, has undermined the reef. This is a common feature
of the stone reefs all along the Brazilian coast, and is due in part to the
fact that only the upper part of the reef is thoroughly consolidated.

in some places this kind of undermining has led to the breaking up of
the reef, and the surface blocks now lie strewn upon the bottom or tipped
about in confusion.

The fact that the outer face of the reef is not attacked more vigor-
ously by waves is due to the protection afforded by the great quantities
of Serpulae, barnacles, seaweeds, and the like that coat its outer surface.

The beach reef at Piedade. —¥ollowing southward along the beach
from the southern end of the Pernambuco reef at Béa Viagem by the
sea one has on the land side a low ridge of sand some four metres high
—the continuation of that at Béa Viagem —and behind this the fresh-
water marshes and Lake Curcurana. ‘The topographic surroundings are
therefore very much the same as those about the southern end of the
Pernambuco reef.

The first signs of a stone reef in this direction are at the Piedade
church, less than a mile south of Boa Viagem. At this place there is a
small beach reef about a hundred metres long. The rock is quite hard,
but not flinty, and is of the same yellowish color as the beach sands,
Its surface is etched in holes and overgrown with a thin coat of green
seaweeds.

The seaward dip of these rocks is clearly shown, and the following
angles were noted : 44°, 5°, 6°, 63°. The following dips of the beach
sands alongside were noted: 4°, 42°, 5°.

68 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

The stone reef at Venda Grande, Pernambuco. — Sixteen kilometres
south of the Pernambuco lighthouse, at a small village known as Venda
Grande, is a small but interesting stone reef. This reef connects with
and is buried by beach sands at its southern end, four hundred metres

-
cease

ATLANTIC OCEAN.

“fal VENDA GRANDE.

of} VENDA GRANDE STONE REEF
. C.E.GILMAN,

MILES, ° 1s /»
KILOS. 6 . ia Be:

Fic. 35.

north of the Venda Grande. Toward the north it draws gradually away
from the beach, so that its northern end is two hundred metres off the
beach.

It has a total length of 1.6 kilometres, including the fragments on the
beach. Unlike most reefs of the kind it ends abruptly: there are no

BRANNER: THE STONE REEFS OF BRAZIL. 69

signs of a submerged continuation of it beyond the northern end exposed
at low tide. The axis of this reef points straight toward the lighthouse
at Pernambuco.

Near the northern end the reef has the profile given below.

meee ew ee RK eee ee ee Ke

HT

eres eee ee Ne eee ee
: der piet Sas - E

Fic. 36. East-west section across the stone reef at Venda Grande.

The top of the reef is pretty well covered with barnacles and worm
tubes. These barnacles and Serpulae seem to start most readily and to
thrive upon the stone legs or sharp points left by the etching of the reef
rocks. The surface pools contain heads of Porvtes.

The rock is a yellowish, rather coarse sandstone, with many fossil
molluscan shells in it. Shells of the same kinds are found in the sands
in the breaks, and on the beach behind the reef. The rock is as hard as
any seen on the reefs, — quite quartzitic in fracture.

The stakes of an ancient fish-trap are still standing on this reef, the
posts apparently driven in the hard rock. Upon inquiry it was learned
that these stakes were not driven in sand which subsequently hardened,
but that the holes for them were drilled in the rock.

In some observations made upon the slope of wet sand behind this
reef I found the steepest angle at which they stood to be 24°. This,
however, was a face of false and not of true bedding.

The Gaibi stone reef. —Gaibi Bay is the embayment immediately
north of Cape Santo Agostinho. At its southern end rise the granite
hills of the cape surmounted here and there by Tertiary sediments.
At its north end is the promontory of Pedras Pretas, a rocky point of
black porphyry hills not shown on the hydrographic chart. The por-
phyry hills stand boldly out in the ocean; inland they are capped by
the Tertiary sediments; nearer the sea these sediments have been
removed by denudation, and only the quartz and other pebbles left
scattered over the surface of the porphyry.

Between these two prominent points runs a line of Tertiary hills
more or less notched on their edges, but swinging inland so as to form
a semicircular enclosure for the Bay of Gaibi. Between the hills and
the bay is a strip of flat land, partly mangrove swamps, partly fresh-
water marshes, and near the beach dry sands and some dunes.

There are three small streams flowing from these flat lands: one of
them discharges at the village of Gaibi at the extreme southern end of

70 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

the bay, another about one third, and the other two thirds of the way
from Gaibi to Pedras Pretas.

Lying along the beach of Gaibi Bay, but here and there a little way
out from it, is a sandstone reef ex-
tending nearly all the way from
Pedras Pretas to the edge of the
village of Gaibi. It is three kilo-
metres or more in length and
varies in width from forty-five to
two hundred and forty metres, —
a remarkable width for a stone
reef. At low tide it stands two
metres out of water at its highest
points. It has a gentle seaward
dip. The rock is of the ordinary
sugar-brown sandstone and con-
tains an abundance of fossil marine
shells. The surface has the etched
appearance so characteristic of the
stone reefs.

The accompanying photograph
(Plate 51) taken from the granite
hills south of the bay shows the southern end of this beach reef.

Ponta de Pedras

Fig. 37. Gaibu Bay.

Fic. 38. Plan of a miniature bay behind a break in the Gaibui reef.

South of the middle of this reef is a small break through which the
waves have been able to encroach upon the beach and to form a minia-
ture bay protected by the ends of the stone reef.

There are many dressed and half-dressed building
stones buried in the beach sands about the southern
end of this reef. These stones are supposed to have
been left here by the Dutch, as no one seems to know
when they were taken out. It used to be supposed
that the reef rock used at Pernambuco and Olinda
for architectural purposes all came from the Pernam-
buco reef. It appears, however, that the Gaibd reef
was the source from which some, perhaps most, of
this stone came. This reef protects no harbor, and,
being close to Pernambuco, and in a bay where boats
could readily be loaded, it offered a convenient source
of supply of these excellent building stones without
trespassing on the Pernambuco reef, which had greater
value as a protection to the port.

The stone reef south of Cabo Santo Agostinho. —
The finest stone reef on the coast of Brazil is the one
lying immediately south of Cabo Santo Agostinho in
the State of Pernambuco. No steamers enter the
port behind this reef and no highways cross the hills
of the Cape above it; being thus of but little com-
mercial importance, the reef is only slightly or not
at all known. Recent charts represent it in a con-
ventional fashion. The best map I have seen of it
is that of Lichthart, the Dutch cartographer, made
more than three hundred years ago, and the only
views of it hitherto published are the woodcuts given
in Liais’ L’ Espace Céleste (pp. 542, 546).

As in other cases, we are concerned to a certain
extent with the physical features of the country on
the land side of the reef. In this instance these
features are so broad that their relations to the his-
tory of the reef are not so clear as they are in the
cases of several of the small reefs with a similar
history, but with a more compact topography.

The features of the region as a whole can be seen
best from the high hills on the southern side of the
cape. The view is superb. To the left the long
straight reef stretches away to the south, a vanish-
ing line. Behind this is the bay with one straight
side against the reef, while the other curves in and
out to meet the three streams, —the Merepe, the
Ipojtica, the Tatudca, and the Suape, that enter it
from the flat lands on the west. Here and there
through this flat region one gets a glimpse of the
shining waters of these streams, but for the most part
they are hidden by the forests that cover the valley.

nla koe
PU Bayete

“
ARC eng
su ora

ATLANTIC OCEAN

From photographs taken from the Cape.

Fic. 40. Panorama of the stone reef south of Cape Santo Agostinho.

Over this valley only a
few small isolated hills
rise above the general
level. The bay seems
shallow save opposite
the Barra do Suape,
the only big break
in the reef, where the
scour of the tides has
kept the silts from
accumulating.

The hills that face
the bay at the cape are
mostly crystalline
rocks, granites, gran-
ite-porphyries, and al-
tered eruptives, with
patches of Tertiary (?)
sediments lying over
and against them.
These hills are about
fifty metres high. From
the cape at the old fort
they strike westward
and after following that
direction for several
kilometres swing south-
ward and finally ap-
proach, but do not
quite reach the sea
again at Serramby
Point, some thirty odd
kilometres from the
Cape. These hills are
of pretty even elevation
where they are near the
coast, but nothing can
be said here of their
forms or elevation at
the west edge or bot-
tom of this ancient
embayment.

On the plain just

a

BRANNER: THE STONE REEFS OF BRAZIL. ie

south of the Rio Tatuéca is a small isolated Tertiary hill, and the hydro-
graphic chart shows another of similar form a little further south.

The essential features of the geology of the region consist of a ridge of
granite and granite porphyries, and other crystalline and metamorphic
rocks of the Cape having an east-west trend, and with Tertiary sediments
deposited against and over them. Denudation has stri pped off most of
the beds that lay upon the Cape crystalline rocks, and has carved out the
embayment that now opens south of it. The shore of the bay from
the Barra do Suape to the village of the same name is all of crystalline
rocks ; a little west of the village a promontory of Tertiary (2) beds
projects into the valley. This hill is of mottled yellow, red, and white
clays and sands ; there are no granites exposed where the Rio Snape
washes its base.

At the village of Suape the beach on the flat is all sandy, and barely
high enough to keep the salt water at high tides from flowing over into
the fresh-water marsh lying just west of it. Tradition says that the bay
at this northern end is rapidly cutting away its western shore. The coco
palm stumps standing in the bay from one hundred and fifty to two hun-
dred metres out from the present beach bear out this tradition,

At low tide great sandy flats are uncovered in the bay. At its south-
ern end and south of Cambéa Point the bay is but a narrow and shallow
pool some twenty to fifty metres wide, into which the tide-water backs,
On the sea side of this pool is the wall-like reef, and on the land side a
bank of white sand five or six metres in height. The sand flats about
the mouth of the Ipojiica and in this arm of the bay swarm with myriads
of little fiddler crabs. These sands also contain a great number of deli-
cate pink shells of bivalves.

The sand ridge on the land side is a wind accumulation ; behind it the
country drops off again to a somewhat lower level.

The Cabo Santo Agostinho reef properly speaking begins on the beach
of the cape itself, just north of the Barra do Sudpe and a few hundred
metres north of the old fort. The rocks of the cape Just here are coarse-
grained granites, and the reef rock lies unconformably against, and
attached to, these granites. There are several of these reef fragments
separated from one another by breaks of various lengths and strewn along
the beach over a distance of a kilometre to the north of the fort. The
section is essentially the same for all these remnants.

The fragment nearest the fort is fifty-three metres wide by forty-five
metres long. The next fragment to the north is ninety metres long
and about fifty metres wide. All these reef remnants have a gentle sea-

74 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

ward slope, rise about as high as the high tides, and have flat tops, —
a topographic configuration in strong contrast with the rounded outlines
of the granites. The reef sands originally sifted into the crevices in
granites and hardened so as to enclose granite blocks here and there.
The rock is a rather fine-grained quartz sandstone of a light brown color.
It contains a few fossil shells.

These fragmentary beach reefs and the Cape of Santo Agostinho itself
are separated from the great stone reef by a gap or break four hundred
metres wide and, according to the hydrographic chart, 43 fathoms deep.
This gap is known as the Barra do Sudpe. It is the only break in the
great reef through which barcagas can enter the bay and the rivers that
flow into it.

If the Suape break were restored, the total length of the Cape Santo
Agostinho reef from the cape to where it disappears beneath the sands

HT.

Fig. 41. Section showing the relations of the stone reef and granite at Cape
Santo Agostinho.

north of the cape would be thirteen kilometres. How much of its
southern end is buried beneath the beach sands we have no means of
knowing. Even to-day, taking out the various gaps, we still have pre-
served a reef something more than twelve kilometres in length.

A striking feature of the Santo Agostinho reef is the long tide-pools on
its surface and running lengthwise of it. Toward the northern end
these pools are not so long or so deep, but toward the southern end there
ig one pool a metre deep and nearly three kilometres in length. In the
photographs taken of the reef near Cambéa, the reef has the appearance
of being double ; and in a sense it is double, for the pool is made by a
softer series of beds that dips beneath the harder ones that form the
reef’s seaward face, and overlies another series of harder ones that forms
the landward face.

From end to end the reef is nearly straight ; there is but one slight
seaward bend opposite Cambéa Point. The surface is for the most part

BRANNER: THE STONE REEFS OF BRAZIL. VS

very even and nearly level along any lengthwise section. The first
break is 3.6 kilometres south of the Barra do Suape. South of this there
follows a series of breaks at various distances from each other over a
distance of three kilometres. Beyond this shattered portion the reef is
solid and unbroken to where it joins the land five and a half kilometres
further south.

It is worthy of note that the breaks in this reef are in front and to
the north of the mouth of the Rio Ipojtica, whose waters are here deflected
to the north. Water runs through and beneath the fragments that lie
scattered in the bottoms of these breaks in the reef.

There is but little difference in the height of the reef throughout its
entire length. In front of the Cambéa residence it is said to be a little
higher than near the Suape bar, but the difference in level is not enough
to be apparent to the eye.

The north end of the reef just south of the bar is from ninety to
one hundred metres wide; along the fractured section north of the
mouth of the Ipojtica it is narrower than elsewhere, and in places here
it is not more than thirty metres wide ; opposite the Cambda residence
it is one hundred and fifty metres wide ; and at the south end where it
joins the land it is from one hundred to one hundred and twenty-five
metres wide.

At low tide the top of the reef seems to be about two metres high
(above low-water level) ; at high tide it is almost completely covered,
only a few blocks scattered over the surface projecting above water.

The following cross-sections made at different points will give a fair
idea of its profile. It should be added, however, that by searching along

Fic. 42. Sections across the stone reef south of Cape Santo Agostinho.

the reef one could find here a section to match any or almost any section
observed on any of the stone reefs of this coast. In the main, though,
this. particular reef is, through its solid portions at least, less broken on
the margins and less open to attack than most of the stone reefs.

76 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

This last section is a typical profile of much of the Cabo Santo Agos-
tinho reef. The outer face is not broken off vertically, but slopes rather
abruptly and with a somewhat irregular face beneath the sea.

At Cambda Point the reef is solid and vertical on its landward face.
At and south of the Camboa residence (1.4 kilometres south of Camboa
Point) the section is as follows :

= curs

Fic. 48. Section of the Santo Agostinho reef at Cambéa.

The features of this portion of the reef are well shown in Plates 53
and 54, from photographs taken July 25, 1899.

As the southern end of the reef is approached, it disappears beneath
the sands of the beach, and the section is thus:

Fic. 44. Across Cape Santo Agostinho reef at its southern extremity.

The great tide-pools that lie on top of and in the axis of the reef have
already been mentioned. These pools abound in corals.and calcareous
seaweeds, and contain some cor-
allines; and it may be fairly
said that small coral reefs have
started in these pools. The
corals are mostly of small spe-
cies, Porites, Favia, and Aga-
ricia. Insome of the shallower
pools some of these calcareous

growths have been broken off

Fic. 45. Tide-pools on the landward edge by theaueke nollecneiie meni:
of the reef. y 4

pebbles, and tossed over on the
sandy beach behind, or left to be rolled still more in the reef pools.
There are still other pools on the surface and in the axis of the reef
but on its landward face ; as shown in the accompanying profile, they are
especially noticeable.

———

BRANNER: THE STONE REEFS OF BRAZIL. Vie

Many of the minor pools on top of the reef contain calcareous growths
and seaweeds in cavities built up by Serpulae, etc.

Sometimes these calcareous growths fasten themselves on points of
sandstone. Here and there sea-urchins with their burrows cover con-
siderable areas, especially on the seaward faces of the reef where the

CHINN Ge Maat Rat rzN E gM ode
ails can “heh

tl
\)
FRE ners ES Te

cars
———

Fic. 46. Points on surface of sandstone reef covered with Serpulae and seaweed.

waves constantly renew the water. These burrows are for the most part
parallel with the currents that flow across them, and hence mostly at
right angles to the trend of the reef. The following is the plan of a
few of these burrows.

These pits are only partially occupied by sea-urchins. They contain
also corallines and some corals (Porites). They are cut in the hard
surface sandstone, and are from
three to ten centimetres deep. The
edges of these pits are generally
overgrown with Serpulae. In the
pools of the reef’s surface are occa-
sionally found water-worn lumps of
Serpulae tubes, apparently broken
from the reef and rolled by the
waves.

There are some cracks in the surface of the reef, most of them run-
ning lengthwise of it. The cracks become more abundant and more
varied where the gaps occur, and they continue so clear across the frac-
tured area. In other portions of the reef they are less abundant than
on the other stone reefs examined.

The rock of this reef is, on the whole, finer of grain than that of the
average. It contains some pebbles, some of them black iron-colored
ones washed from the mottled Tertiary plateaus. Most of the rock is
hard, light, sugar-brown sandstone cemented with lime carbonate.

Everywhere the body of the reef is covered with Algae; on top they
are mostly green. It is etched a little on the landward side, probably
by the acid waters of the streams, just enough to bring out the bedding,

Fic. 47. Plan of the pits on the sur-
face of Cabo Santo Agostinho reef.

78 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

but it shows very little or no signs of active or rapid wearing of the
rocks.

The surf that breaks against the outer face of the reef is heavy, for it
comes in from an open and deep ocean where there are no coral reefs to
break its full force. The depth of 44 fathoms marked on the hydro-
graphic charts outside comes close up to the reef along most of its
length. It is remarkable that this violent surf has not affected the reef
more than it has. There are but few blocks tossed upon the top of it ;
one of these, however, weighing more than forty-eight short tons, has
been hurled almost the entire width of the reef, and now rests within a
few metres of its Inner margin.

Mention should here be made of the possible relations of the Cape
Santo Agostinho reef to a small coral reef just off Cipe Point. The
stone reef is in line with the beach to the south for half a kilometre; the
beach then swings eastward to and around Ciipe Point. East of this
point a coral reef about six hundred metres long lies a few hundred
metres off shore. Now the Cape Santo Agostinho reef, like the others,
has a gentle seaward dip. If this reef continues southward to and
passes beneath the sands west of Ctipe, its dip must carry it beneath
the coral reef that lies east of that point. (See map of Cape Santo
Agostinho reef, p. 71.)

The beach rocks at Porto de Gallinhas. — Porto de Gallinhas is a little
village on the coast fifteen kilometres south of Cape Santo Agostinho.
It is on a sandy flat with fresh-water marshes between the village and
the hills just west of it.

There are some rocks of recent origin at this place which, on account
of their possible relations to the coral reef off the coast, are worthy of
mention. These rocks are like the ordinary reef rocks, except that

.
Fic. 48. Section showing the relation of coral reef to beach sandstone at
Porto de Gallinhas.

they contain rather more than the usual amount of calcareous Algae
fragments. They are exposed when the tide is out at the large ware-
house that stands on the edge of the beach near the anchorage. Again,
south of the village, at the first westward turn of the beach, soft cal-
careous sandstones are exposed on shore by the recent encroachment
of the sea. These beds have the usual seaward dip, which, if it con-

BRANNER: THE STONE REEFS OF BRAZIL. 79

tinues that far, must carry them beneath the coral reef that lies a few
hundred metres off shore at this place.

The Cacimba and Serinhaem stone reefs. — The Rio Serinhaem enters
the ocean in south latitude 8° 36’, just east of the island of Santo
Aleixo. The Cacimba and Serinhaem reefs lie across
the mouth of this river and in front of the flat lands
immediately north of it.

The Cacimba reef is largely on the beach at the bot-
tom of the embayment between Ponta do Serramby and
Rio Serinhaem, while the Serinhaem reef lies across the
mouth of the river and extends well to the north, afford-
ing partial protection to the embayment west of it.

The country west of these reefs consists of a narrow
strip of sandy land next to the beach, with mangrove
swamps and sandy flat lands behind. These low flat
lands about the mouths of Rios Serinhaem and Trapiche
extend back to the foot of the Tertiary hills that rise
a few kilometres inland.

At the town of Barra de Serinhaem, soft black Ter-
tiary sandstones are exposed at low tide along the river
bank for a distance of several hundred metres.

The northern end of the Cacimba reef begins on the
beach south of Ponta do Serramby at a place called
Cacimba. A sand bank three metres high rises on the
land side of it, and two hundred metres west of the beach
a mangrove swamp follows southward parallel with the
shore.

The northernmost four hundred metres of this reef
lies upon the beach ; then follows a break, beyond which
it touches the beach at only one point. It is a striking
and interesting fact that the southern end of this reef
curves gently eastward with the beach, keeping always
parallel with it and from forty to sixty metres away
from it.

The south end of the Cacimba reef is more or less broken, until at last
it appears only as isolated patches, and finally drops in behind or land-
ward of the Serinhaem reef, and comes to an end.

About its northern end this reef stands fully two metres out of water
at low tide ; near its south end it is not quite so high. The surface is
much cracked, broken, and etched lengthwise, and there is a great

Section across the Cacimba stone reef.

49,

Fia.

80 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY.

number of holes, from three to seven decimetres across, eaten straight
down into the body of the rock. This peculiar form of etching or decay
has been seen on no other stone reef.

The bedding is plainly visible, and several observations show that the
dip is seaward at an angle of from seven to nine degrees.

Here and there along the outer edge, the reef has been more or less
undermined, and great blocks of stone have been detached and their
outer edges have sunk.

The surface of the reef is unusually rough, ragged, and etched, and
many loose blocks lie over the top. The rock is very hard and quartz-
itic in fracture, and rings when struck with the hammer.

Eight hundred metres south of its northern end, there is a break in this
reef through which the sea has been able to cut out one of the beautiful
little semi-lunar bays mentioned and described elsewhere in this paper.

The Serinhaem reef is a straight one lying between the shore and the
island of Santo Aleixo. Its total length is between three and four
kilometres, and its bearing north 50° east, magnetic. The south end
of the reef is about half a kilometre south of the mouth of Rio Serin-
haem, while the north end projects boldly across the embayment south
of Ponta do Serramby. The north end is broken, and its extreme point
in that direction is represented only by sunken rocks. Near its middle,
and opposite the river’s mouth and a little south of it, this reef is a
double one; or, if the Cacimba reef be considered, they may all be
looked upon as a treble reef. Of this group the Serinhaem is the outer
one, the Cacimba reef is the landward one, while a third reef lies about
halfway between them.

This middle reef is more or less fragmentary, yet clearly defined both
in its position and its direction. It is parallel with the reefs on both
sides of it.

It was noted the last time these reefs were visited (July 26, 1899),
that the muddy waters of the Rio Serinhaem were discharging to the
southward and not northward, as do most of the streams along this part
of the coast.

The stone reef of Santo Aletxo. — Santo Aleixo is a small island oppo-
site the Barra de Serinhaem, and about two and a half kilometres from
the main land. It is also known to navigators as Donally’s Island. It
is eight hundred and eighty-three metres long, its longest axis being
north-south. The body of the island is of quartz porphyry,’ which on

1 In his Espace Céleste, p. 548, Liais says the rocks of Santo Aleixo are eurities
and diorities; in his Climats Geologie, etc., he says they are amphibole and mag-

BRANNER: THE STONE REEFS OF BRAZIL. 81

the southeast corner rises to a height of twenty-one metres. On the
western side of the island is a small bay, south of which is a quarry
in the igneous rocks. Next to the quarry there are remnants of a
calcareous fringing reef upon the beach, extending from that point to
the southeastern point of the island. Along the shore of the little bay
on the south side of the island is a piece of consolidated beach or stone
reef. The rock is made of bits of shells, corals, sands, etc., exactly like
the unconsolidated sands of the present beach. It is not hard and solid
like the reef rock of Rio Formoso, but is soft and porous.

This reef is between one hundred and fifty and two hundred metres
in length, is from four to five metres wide at the widest, and is so high
in places that only the very highest tides wet it entirely. On the land
side it is buried beneath the beach sands, but toward the sea it is abrupt
in places. It seems to be wearing away rapidly.

The sandstone reef of Rio Formoso.!— Rio Formoso is an estuary in
the State of Pernambuco, sixty kilometres southwest of the city of
Pernambuco, and thirty-four kilometres southwest of Cabo Santo Agos-
tinho. An isolated Tertiary hill stands back from the coast west of
Gamella, and another stands just north of Rio Formoso. Against these
hills lies a plain of later geologic age, that rises about eight or nine
metres at most above high tide-level. Northwest of these hills, and
north of the estuary, is a broad, low, flat country partly covered by loose
sand and growing orchards of caju trees and other caatinga plants, and
partly also by extensive mangrove swamps. Beyond (west of ) this flat
valley rise the low, approximately flat-topped table-lands of the interior,
— in this vicinity composed of granites, gneisses, and crystalline schists.

The structure and character of the Tertiary hills is shown where the
tides of Rio Formoso have cut away the foot of the hill upon which
stands the Church of Nossa Senhora da Guadalupe. The rocks are soft,
white and gray sandstones, and red and yellow mottled clays dipping
gently seaward.

The rocks that lie against these Tertiary hills are well exposed all

nesian porphyries (p. 260). My determination of this rock was made after a
microscopic examination by the late Dr. George H. William from material gathered
by myself.

(The Cretaceous and Tertiary geology of the Sergipe-Alagéas basin of Brazil.
By J.C. Branner. Trans. Amer. Phil. Soc., 1889, XVI., p. 404, foot-note.)

In his Climats Geéologie, etc., du Bresi] (p. 252), M. Liais speaks of Tertiary
sediments on the island. The beds he refers to are these recent sandstones.

1 This description of the Rio Formoso reef has been published in Portuguese
by the Instituto Archeologico e Geographico Pernambucano at Pernambuco, Brazil.

VOL. XLIV. 6

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BRANNER: THE STONE REEFS OF BRAZIL. 83

along the beach between Gamella and Guadalupe. The section and
geologic relations of these beds are shown in the sketch on p. 30.

mouwlty of
“Rio Eornoso

.
Ota eee POO) ols
se we . .

Oo KS Se (ir ae mite
r SOR SOLAS OI OS ARC | A WY

PORE Peek es ae MA 54 ieeotehis de Janeiro ° a Kilometer

Fic. 51. The dotted line on the north side of the mouth of the river shows the
position of the shore in 1875; the solid line to the west shows the shore in 1899.

Pure white quartz sand

oa) ee ee i re STO ae
BicmscimnsamdstOne =. . « + ee lw CUS

Yellow clay seam 3) ae al che are oe 1-2"
Peaienm@nsanasane =. =... . 5 . . we Ot
lvesaudy clayat base =< 2 sw ek CP

‘1 These white quartz sands are well adapted to the manufacture of glass. The
bed in places is four metres thick, but for most of the distance from Gamella to
where the sands abut against the Guadalupe Tertiary hill, they have been blown

84 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

The lowest two beds of this section, below the yellow clay seam, are
Eocene Tertiary, and similar to the beds exposed on Rio Formoso, south
of the Guadalupe church. The beds above the clay seam rest uncon-
formably against the early Tertiary as shown on p. 30.

The sandstone reef of Rio Formoso (not including here the southern
end buried by the sands and to be spoken of further on) begins on the
southwestern side of the river or estuary on the Praia dos Carneiros, and
extends northeast in an almost straight line across the mouth of this
stream, and at right angles to it.

The northern end of the reef curves westward slightly but distinctly ;
this curve, however, is not apparent on the small-scale map given
herewith.

On an average, the reef is twelve metres in width, and stands a little
more than one metre above water at ordinary low tides. Its entire
length is* two thousand and seventy metres. Its general appearance
varies somewhat with the locality: near the south shore, to which it is

eres fh =

Fic. 52. Profile of the etched sandstone reef at Rio Formoso.

united, it is broad and flat, and comparatively smooth. Structurally
this reef has a slight but very apparent seaward dip. In surface
contour, the outer or oceanward side generally slopes at an easy angle
along the whole length of the reef, and as it dips beneath the water
becomes covered by corals and other marine animals and plants and
their skeletal remains. In many places the top is covered by rough
jagged points left by the wearing or etching away of the softer or more
solnble surrounding parts of the rock. These points are a third of a
metre or less in height, and often so close together and so sharp as to
make walking through or over them almost impossible. They are
extremely hard, and can be broken only by a sharp blow with a heavy
hammer. When struck, the larger ones ring with a clear metallic

up from the seaward side, and heaped upon the original bed, until they are from
five to seven metres thick, and three or four hundred metres wide. If there should
be any demand for such materials in this part of Brazil, a short tramway along
the front of these beds could deliver the sands on board of barcagas at the foot of
the Guadalupe hill.

1 Liais speaks of a triple line of reefs at Rio Formoso. (L’Espace Céleste, 549.)
There are no such reefs at this place unless one considers the patches of coral
outside the stone reef as such.

BRANNER: THE STONE REEFS OF BRAZIL. 85

sound. The surface of the Rio Formoso reef, however, is not, on the
whole, as ragged and rough as those of many other of the stone
reefs.

The broken stone generally shows quartz sand mixed with some
pebbles and shells. The pebbles are also of quartz, and the shells are
of bivalves, gasteropods, etc., such as live at present along the coast in
the vicinity. The shells most abundant are the prettily colored bivalves
Venus, popularly known here as mariscos.

In many places, in fact, in almost all parts of the reef, cracks appear
to have been formed and then to have been filled up again with sand
that has hardened like the rest of the reef. These cracks have generally
the same direction as the reef, but they sometimes cross it at right
angles, and at other times diagonally. In two places the reef has small
breaks nearly or quite through it, crossing diagonally, and with the
appearance of being due largely to the presence of the cracks.

From the land end on the south outward there is no break of impor-
tance until about halfway the whole length of the reef, where there is
a baretta or passage for canoes and jangadas. This break is known as
the barreta das jangadas. It is here that the reef receives the full
force of the ebbing tide as it comes down from the river. From the
barreta das jangadas to the outer end, the side facing the river is
either perpendicular or overhanging. In the barreta itself the rocks in
the bottom of the passage are hard and appear to be the same as those
on the surface of the reef at other places. I suppose the rocks in the
bottom of the passage to have formerly stood even with the surface of
the reef, but being undermined by the strong sand-laden currents, they
have lost their support and fallen where they now lie. These blocks, or
more properly slabs, are all large and broad, and of the same average
thickness as the harder upper part of the general body of the reef.

From this place to the outer end, five hundred and seventy metres,
there are two other breaks, both of them smaller and of less importance
than this one.

The whole of the riverward face of the reef is undercut. Blocks have
broken away where left without support, and in one place especially,
very large pieces have fallen, and, with one end held fast by the sand
and mud of the bottom of the channel, remain with the other end
tilted high in the air. One of these is go high that it is not covered
even by the highest tides ; this one is popularly known hereabout as the
Pedra de Nossa Senhora, or the Rock of Our Lady.

At still another place the reef is entirely undermined, while the sur-

86 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

face rock still remains in place. A large body of water flows through
underneath this bridge with every ebbing and flowing tide.

OCEAN-SIDE

Fic. 53. Sections across the Rio Formoso sandstone reef.

Along the landward side the bottom of the channel next to the reef
is covered here and there by huge blocks of stone like the upper part
of the reef. There are tide-pools over the surface, especially near the
landward end. At the outer end the reef breaks off abruptly, and there

BRANNER: THE STONE REEFS OF BRAZIL. 87

are no indications of a northward continuation of it, unless they be
in the sunken rocks further out, and over which the waves break at low
tide. These breakers lie in the axis of the stone reef.

There is a coral reef off shore at Praia da Gamella also in the axis of
the stone reef ; possibly it is built upon a base of sand rock.

The outer or northern end of the stone reef is covered with barnacles.
A coral reef beginning here on the east side of the rock reef bends back
toward the south, and, being separated from it by a channel, protects it

Fic. 54. Longitudinal section of an undermined portion of the stone reef,
Rio Formoso.

from the force of the waves of the open ocean. It is only at their out-
ward or northern ends that these two reefs are joined ; the channel sep-
arating them becomes wider and wider till it passes the Barreta das
Jangadas, and at this end it is more than a hundred metres in width.
This channel has a bottom of coarse calcareous sand with very fine mud
in some places. Corals and other organic calcareous growths have
spread over the outer side of the sandstone reef, and in many places
have grown upon the stone reef as a base until they are now near the
surface of the water.

It is noticeable that we here have corals thriving in front of a river
mouth. The fact is that the stream is deflected to the north by the

Fic. 55. Across Rio Formoso stone and coral reefs. The darker portions are corals.

stone reef which thus protects the corals from the mud and fresh water
entering from the river. A similar state of affairs is found at several
other places along this coast.

From the land end of the stone reef, following southward along the
sandy beach to a distance of eighteen hundred metres, there is another
(or the same) stone reef joined to the land and running out into the
embayment so as to make an angle of about twenty degrees with the
beach. This reef is about seventy metres wide. Just where it joins
the. beach the rock is the coarsest seen in this vicinity, the pebbles
being as big as pigeon’s eggs. The piece is only short, being about

88 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

three hundred metres long. Beyond this, however, there are several
isolated patches lying in the direct axis of this portion and stretching
halfway across the embayment or curve in the coast line north of
Tamandaré. This bit of reef, together with the isolated fragments at
its southern end, is in a Jine with the stone reef of Rio Formoso. Just
behind or landward of this small reef, and about a hundred metres from
it, there is still another sand reef lying along the beach. This on-shore
reef is parallel with the outer one, but in composition it is softer, though
of the same kind of material. It has a gentle dip seaward. Its sea-
ward face is broken off squarely wherever the open sea strikes it.

There are also a few remains of hardened sand rock between the Rio
Formoso reef and the high lands west of it, but these remains or bits
are scattered, and without the linear arrangement that characterizes
the stone reefs. One of these localities is at Gamella Point, where soft
calcareous sandstone is uncovered by the encroachment of the sea. At
the Guadalupe Point, where the sea is also encroaching, a soft calcareous
rock is being uncovered at high tide-level, less than a metre below the
surface of the sandy soil.

The map herewith, and most of the observations embodied in the
part relating to Rio Formoso, were made by the writer in 1876. On
revisiting the place in 1899 considerable changes were noticed in the
beaches. At Gamella Point the sea was found cutting the land so that
a large Gamelleira tree, that in 1876 was well up on the beach, and
beyond the reach of the sea-water, is now a dead stump a dozen metres
to the seaward of the high tide mark. Guadalupe Point is being cut
away on the east side and filled in on the west. The holder of the
property at this place states that he has lost more than a thousand
coco palms by the encroachment of the sea during the last seven years.
This point was mapped again July 27, 1899, and the two outlines are
shown, with their appropriate dates, on the accompanying map.

The stone reefs of the Rio Sapucahy, Alagéas. —The Rio Sapucahy is
a small river in the State of Alagéas entering the ocean about thirty
kilometres (in a straight line) northeast of Maceio, and three kilo-
metres northeast of the village of Paripueira. The country west of
the mouth of the river is, like most of the northern coast of Alagéas, a
plateau of Tertiary sediments cut across by the river, and a strip of
low flat land, partly mangrove swamps and partly sand flats, intervening
between the base of the hills and the ocean.

The Sapucahy stone reef lies right across the mouth of that river,
and the stream debouches right and left round both ends of it. It is

BRANNER: THE STONE REEFS OF BRAZIL. 89

1.08 kilometres in length, not including some submerged fragments at
its southern end, is from fifty to one hundred metres off the beach, and
stands nearly two metres out of water at low tide. It is not connected
with the beach at any point, and is almost solid from one end to the
other, being broken a little only near its southern end.

STONEREEFS }-:.°-": a
RIO SAPUCAHT ican

CE. GILMAN. jee ha

Fie. 56.

An interesting fact about this reef is that it has a gentle curve par-
allel with the beach behind it, —a peculiarity I do not remember to
have observed in any other of these sandstone reefs.

Following the beach southward from the mouth of the Sapucahy, it
curves gradually seaward and then back landward again, forming a sandy
point, part of which is shown on the accompanying map. At a distance
of 1.4 kilometres from the mouth of the Sapucahy, this sandy point laps
over one of the coral reefs that here run parallel with the coast. And
just at this point on the beach begins another reef of sandstone.

This particular reef is eight hundred metres long, not including some

90 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

detached fragments lying beyond its southern end, and not shown on
the map herewith, which would give it a total length of something more
than a kilometre.

A fact of unusual interest in regard to this bit of reef is that 7 over-
lies a dead coral reef. The overlap is plainly visible at many places

Fic. 57. Section across the stone and coral reefs at Sapucahy. The vertical
shading on the right represents the coral reef.

where re-entrant angles have notched the stone reef, or where large frag-
ments have been left isolated but fast to the coral reef.

The coral reef visible here at low tide is from one hundred to two
hundred and seventy metres wide, measured from the outer margin to
where it is overlapped by the stone reef or by the beach sands. This
coral reef is almost perfectly flat and level. Not a single living coral

Fic. 58. Sketch map of the southwest end of the stone reef at Paripueira,
State of Alagoas.

could be found on its upper surface; the coral most abundant in the

rock itself is Porites.
Outside or seaward of this reef is still another coral reef with which
the inner one is not connected at the water’s surface at least.

BRANNER: THE STONE REEFS OF BRAZIL. 91

The sandstone reef lies at a higher level on the beach than the coral
reef, and has throughout most of its length a decided seaward dip. At
the southern end of its contact with the beach, however, the dip is re-
versed and the bedding looks very much as if it had been formed by
sand washed over and behind a low beach or spit. The rock is in some
places rather soft, in others it is quite hard and rings when struck with
the hammer. It contains many shells of living forms of mollusks, es-
pecially mariscos, and also calcareous Algae.

Certain features about the southern end of these reefs are interesting
in connection with the coast history.

There is here a mangrove swamp being encroached upon by the sea, —
a somewhat unusual process. The swamp, as will be seen from the
sketch, was formerly protected by the reefs, but the sea has gradually
broken down this barrier and, encroaching upon the shore about its
southwest end, has attacked the mangroves. In the embayment south
of the existing swamp and reefs the shallow bay contains a great many
dead stumps of mangrove trees still standing in place.

The stone reefs of the Pratagy, Alagéas. — The Rio Pratagy is a small
stream, not more than sixty metres wide, entering the ocean eleven or
twelve kilometres north of Maceio. Where this stream enters, a small
sandstone reef lies square across its mouth.

Both north and south of the Pratagy and within a short distance are
other reefs or fragments of stone reefs that may be considered as parts
of the one in front of the river’s mouth.

The chief features of the topography of most of this part of the coast
consist of a flat-topped plateau of Tertiary sediments rising abruptly
from near sea-level to an elevation of from fifty to a hundred metres.
The margin of this plateau is cut across here and there by streams com-
ing down from the interior and forming, especially near the coast, rather
steep-sided, flat-bottomed valleys.

It is through one of these valleys that the Rio Pratagy enters the
sea. The narrow strip between the mouth of the river and the foot of
the Tertiary escarpment is low, flat, and mostly sandy, but near the
stream covered with mangrove swamps. Just back of the beach and
parallel with it is a somewhat higher bank of sand, apparently blown
up from the shore. |

The first or most northern of the Pratagy reefs begins on or near the
beach one kilometre northeast of the mouth of the river. It is here
only fragmentary, — one large piece after another, but lying always in a
line, a little way out from the high-water beach and just covered at high

92 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

tide. This reef runs into the beach four hundred metres north of the
river. It has a decided dip to seaward.

Following along the beach a hundred metres or so from the southern
end of this reef, one comes up behind a second stone reef that stands out
in the water some seventy-five or one hundred metres from the beach.

Fia. 59.

4

RIO PRATAGY

BY
C.E. GILMAN.

Wn
En.
tid
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Ge.
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—<s--"-RIACHO DOCE.

Just around the turn of the shore is a third reef, — this one upon the
beach. It dips seaward beneath the outer reef, which is here only about
forty metres away from it. The size and position of this shore reef are
shown on the accompanying map.

BRANNER: THE STONE REEFS OF BRAZIL. 93

The outer reef is the largest, or rather the longest and most compact
of the three at this place. It is the Pratagy reef, properly speaking, and
lies across the mouth of the river, which flows north and south round
both ends of it. It has a width varying between eight and twenty
metres.

The rocks of these reefs are quite hard and compact, and of a light-
brown color.

One hundred and seventy metres south of the Pratagy reef is another
one of similar materials upon the beach. This one is about four hun-
dred metres long and seems to be a part of the southward continuation
of the inner or beach reef exposed just north of the mouth of the river.

The rock of this particular beach reef has a decided seaward dip, but
in addition the top of the reef is worn off so that the upper surface
itself has a seaward slope.

Fic. 60. Section of the Rio Pratagy sandstone reef.

This characteristic has been observed in several other of the rock reefs
of the coast.

It is noticeable that these Pratagy reefs are not straight.

Outside of the outer stone reef are two other parallel sets of reefs.
These reefs were not examined, but from their general appearance I
judge them to be coral reefs. The most distant one of these appears
to be about one kilometre out from the beach and approximately parallel
to it.

The stone reefs of Bahia. —I have visited the stone reefs of Bahia
several times, especially those at and near the lighthouse at the en-
trance to the bay, but I have not examined their full extent along the
coast to the east of the lighthouse. As is well shown in the accom-
panying illustration of these reef-rocks, the blocks about the lighthouse
have the appearance of having been undermined and broken into great
angular slabs.

The Bahia reef is not exposed in a long beach-like line, as are most of
the other sandstone reefs. Here there has been no stream entering the
ocean from behind a bar, but the horizontal sand rock has been exposed
by the encroachment of the sea upon accompanying beds. The reef
appears to rest upon the edges of crystalline rocks.

94 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

The reef rock contains shells of marine mollusks now living along this
coast, and Capanema mentions seeing pieces of pottery imbedded in it.

The rock has been extensively quarried for flagging and for building
purposes,

When I revisited the reef at this place in August, 1899, I found west
of the lighthouse only one big slab of the reef rock. This slab is
5 X 2.1 X 0.5 metres. It lies loose upon the projecting points of the
crystalline rocks of the beach as if it had been tossed there by the waves.

There must have been a beach reef at this place formerly, but it has
now all been removed by man and the surf save this one slab and a few
isolated patches of heavy conglomerates here and there among the ragged
points of the crystalline rocks beneath them.

Among these conglomerates several fragments of bones were noted.

The following description of the Rio Vermelho reef, which I did not
examine, is taken from Hartt:? ‘The reef at Rio Vermelho illustrates
very well the general character of these consolidated beaches. It is
composed of layers of calcareous sandstone and conglomerate, often
somewhat irregular, dipping seaward, the dip being only a few degrees,
or about that of an ordinary sand beach. The height of the reef is very
uniform. In the finished and isolated reefs, as that of Pernambuco and
the one under consideration, the recent rise of the land has brought this
level somewhat above that of the sea. The solidified portion is seen to
be but a sheet of varying thickness lying on the surface of the beach.
On the inner side it is quite thin, and from the action of water behind
it is undermined and broken off, until, at last, it forms a low perpen-
dicular wall, undermined below and sometimes projecting several feet.
Usually this side of the reef is flanked by a slope of sand or mud, and
sometimes by large oblong blocks of sandstone. (See cut on p. 109.)
The surface of the reef is, broadly speaking, horizontal, but it is marked
by longitudinal ridges and much worn away, sometimes honeycombed
and exceedingly rough with large, shallow or deep irregular pools of
water, the homes of several species of corals, etc. The whole mass is
divided by joints into great blocks. On the seaward edge the reef is
often worn away by the waves and undermined, presenting always a per-
pendicular wall to the sea. The upper bed almost always projects a
little, and the great blocks broken from it lie in front, which afford some
protection to the reef. One often finds a depth of twelve to fifteen feet

1 Guilherme S. de Capanema. Trabalhos da Commissio Scientifica de Ex-

ploracio. Introduccaio. I. CXXXVII.
2 C. F. Hartt, Geology and physical geography of Brazil, p. 344-845.

BRANNER: THE STONE REEFS OF BRAZIL. 95

or more at low tide along this side of the reef. In most cases corals
grow on the faces of these reefs below low water.”

The stone reef at Santa Cruz. — Santa Cruz, in the State of Bahia,
is a small town about two hundred and seventy kilometres south of the
city of Bahia. It stands at the mouth and on the south side of the Rio
da Santa Cruz, which river enters the Bahia de Cabral from behind and
around the north end of a stone reef.

The general topography of the region about Santa Cruz is worthy of
special note. There is a striking resemblance between it and the topog-
raphy of Porto Seguro.

The flat-topped hills with an elevation of about fifty metres here come
down to the shores. The plateau is cut across at this place by the
Santa Cruz river. The valley, however, instead of being v-shaped, is
steep only at the widely separated margins, while the floor of the valley
is broad and flat. The hills at the town of Santa Cruz and on which
the church stands are so steep on the northwest side that they are nearly
perpendicular at several places. Low mangrove swamps are visible about
the mouth of the river and follow up this stream for many kilometres,
but it is to be noted that there is both near the mouth of the stream and
further up the valley much land standing at an elevation of about three
metres above tide. This is flat land, however. The reef extends right
across the mouth of this valley, but stands a little way out from the hills.
The river strikes the reef near its southern end, bends northward, and
enters the sea around the north end of the reef. The south end of the
reef laps back against the beach opposite the town. At its north end
it is double, and as it breaks down isolated rocks continue for a few
hundred metres beyond the end of the solid rock. At low tide this reef
appears to stand about two metres out of water.

To the landward of the reef is a long line of mangrove swamps, so that
unlike most of such reefs this one is not much undercut by the river that
flows from behind it. It has a large break at one point.

I saw but little of the Santa Cruz reef and therefore give Hartt’s de-
scription of it.1 He says that it begins ‘on the shore just to the south
of the village, continues in the trend of the beach, which is north a few
degrees east, with an occasional break for a distance of about two miles,
the river flowing behind it and escaping around its northern extremity.
At low water the breakers show that the reef is continued under water
with the same general trend northward, tying in with a reef which, be-
ginning at a point about a mile north of the river-mouth, fringes the

1 Geology and physical geography of Brazil, p. 232-234.

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Fie. 61.

BRANNER: THE STONE REEFS OF BRAZIL. 97

beach for more than half a mile... . In front of the town the reef
clings to the shore, though there is a channel behind it filled at high
water. The reef is much shattered, and great blocks lie tumbled about
in confusion, broken from it by the waves. . . . At the extremity the reef
is double, the remains of an old reef being visible on the outer side.”

The stone reef of Porto Seguro..— The Porto Seguro reef, like so
many other of the stone reefs, lies across the mouth of a valley through
which a river — in this case
the Buranhaem or Cachoe-
ira — enters the sea. North
of this valley the coast hills,
from forty to fifty metres in
height, are close to the
beach, but here and there
are cut at right angles by
narrow valleys. These hills
with their flat tops come
close to the valley of the Cachoeira, where they are cut down abruptly
and left with an almost wall-like face standing at an angle of forty-five
degrees or more.

In the accompanying sketch (Fig: 62) the profile of the hills is seen
where the face of the hill intersects the water horizon. About balfa

Fic. 62. Porto Seguro from the sea.

Be ey 2 or
Fs Bi tee 3 ae ee
te, Bee Ee? % age
Paice
y = a
SO ae —

Fic. 68. Valley north of Porto Seguro.

kilometre north of the upper city a narrow valley cutting across these
hills has the outline shown in Figure 63.

1 The map of Porto Seguro and its reef herewith is from a survey made in 1876
by Luther Wagoner, member of the Commissio Geologica do Brazil. It has not
been published before.

VOL. XLIV. 7

98 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

On the brow of this bluff stands the old town or upper city of Porto
Seguro. The view from the edge of the plateau is remarkably fine, and
throws much light upon the geographic history of the region. The ac-
companying sketch was made from the southwestern edge of the plateau
in the outskirts of the old town.
It was made so late in the day,
however, that the details of the
hills on the south side of the val-
ley could not be seen. South of
the valley these same steep-faced
hills continue down the coast.
The valley of the Rio Cachoeira
is flat-bottomed, here sandy and
there covered by mangues that
extend back and up the smaller
channels from the margin of the
main stream like fingers from a
hand. This flat valley, about its
lower end at least, is less than
one metre above the highest tides.
On the south side of the river is
a caatinga forest where the land
is four metres above mean tide
(Wagoner).

The Porto Seguro reef has its
southern end joined to the land
and lies square across the mouth
of the valley and of the Cachoeira
River, which it deflects northward.
The main unbroken reef is one
thousand six hundred metres long,
but beyond this to the north and
lying in the line of the reef are
four separate pieces which add
six hundred metres more to its
length. It varies in width from one hundred and thirty-five metres near
its southern extremity to thirty metres in the narrowest part of the main
reef; throughout the greater part of its length it averages thirty-five
metres. At high tide the water breaks over it the entire length, but it
is more effective as a breakwater than the Pernambuco reef. Its general

£7

Pr4

i
aN
A
ANS
\
\
As
:
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From a sketch made at

the edge of the plateau at Porto Seguro.

Fia. 64. The region about the mouth of Rio Buranhaem or Cachoeira.

BRANNER: THE STONE REEFS OF BRAZIL. 99

effectiveness is due to the coral reef that lies outside, however, and
greatly reduces the force of the surf that reaches it. At its southern end
it is split in two. South of this end and in a general line of the main reef
are five or six isolated rocks that are probably remnants of the reef in
that direction. North of the north end of the reef there is no flat land
on the beach, the cliffs coming close up to the water. There are no rocks
on the beach as shown on the hydrographic charts.

The reef has the appearance of having been nearly everywhere more
or less cracked and these cracks filled with sand which is now hard like
the rest of the rock. In places the cracks have been washed open to a
depth of more than half a metre. The cracks run in every direction,
but the greater part of them are parallel with the reef. Along the sides
blocks from three to six metres long and from one to four metres across
have broken away from the main reefs on both sides and have sunk into
the sand and mud next to the reef. In some places the reef rock over-
hangs on the landward side where it seems to be undercut by the stream
or outflowing tide.

North of the river the old town of Porto Seguro stands upon a plateau
forty-five metres high, and for the most part covered with forest.

The following description of this reef is given by Hartt, who examined
it in 1865:1 “The rock is obliquely laminated as in a sand beach, the
lamina dipping seawards at a small angle. It is composed of rather
fine sand, with occasional small pebbles, compactly held together by a
calcareous cement. It contains an abundance of recent shells, Venus,
Cerithium, Chama, etc., such as now live on the sea beaches of the
vicinity.”

There is, however, a marked difference between the rock of this reef
and that of the others. The sand is much whiter and, on the average,
coarser. Many of the pebbles are as large as pigeon’s eggs, and the
fossil shells are moderately abundant. In one block I found a piece of
the coral Porites embedded in the reef rock. In places the reef rock is
exceedingly hard and breaks through the quartz grains with an almost
glassy fracture.

My general impression of the Porto Seguro reef is that it is one of
the weakest of the Brazilian stone reefs. It is an important one because
it protects the port in the great Cabral Bay already partly protected
by the great coral reefs outside.

Notes upon little-known stone reefs. — The preceding detailed descrip-
tions of individual stone reefs contain all the notes made upon the reefs

1 Geology and physical geography of Brazil, p. 229.

100 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

thus far examined. These, however, are not the only stone reefs of the
northeast coast of Brazil. There still remain several that have not been
examined and about which very little is known. Under the circum-
stances it seems best to give that little here, and to mention the places
at which stone reefs are reported, whether anything else than their
existence is known about them.

Some important reefs may have been omitted from this list, but it is
doubtful whether facts to change any of the conclusions reached would
have been obtained by an examination of the reefs not seen.

In mentioning “reported” reefs, proper allowance has been made, in
so far as possible, for the general disposition to lump all the reefs of this
coast together. To navigators all reefs are pretty much alike, so much
so that the Pernambuco stone reef, the best-known one of Brazil, is often
put down in sailing directions for the south Atlantic as a coral reef. The
confusion is further increased by the customary addition that this same
reef borders the whole Brazilian coast. With such reports as these we
try to have nothing to do.

On my trip from Pernambuco to Natal in June, 1899, for the purpose ,
of studying the reefs, it was not possible to examine all the places that
it was desirable to examine because of the inaccessibility of the shores
for the barcaga in which the trip was made. This difficulty was evaded
in some instances by following the beaches on foot, but this was not
always convenient, and necessarily delayed the work.

Guaju. — There is a line of reefs beginning three or four kilometres
south of Pavuna (S. lat. 6° 32’), in the State of Parahyba, and stretch-
ing across the low lands in front of Rio Guaji. Rio Guaju enters the
sea through a flat valley between rather steep-faced hills. This reef was
not examined, but its configuration and the nature of the country back
of it lead me to believe it to be a sandstone reef.

Sargi. — Across the mouth of another small stream north of the
Guaju, probably the Sargi, is a reef which, seen from the ocean, has
every appearance of being of sandstone.

Joto dos Santos. — At Joio dos Santos a stream enters the ocean and
reefs lie across the mouth of it and extend two or three kilometres to the
south. The geography and general appearance lead me to believe it to
be of sandstone.

Tibdau. — At Tiban (S. lat. 6° 11’) a small stream enters the ocean
from behind a short reef that appears to be of recent sandstone.

Camorupim. — About 2.5 kilometres north of Tibau begins a stone
reef which continues northward for several kilometres very close to and

BRANNER: THE STONE REEFS OF BRAZIL. 101

in places on the beach itself. This reef is broken at the mouth of Rio
Camorupim. I was told by persons living near Rio Pirangy that this
reef continues to the north of the Camorupim nearly to Tabatinga. I
was also shown blocks of stone said to have been taken from this reef.
“Fhe rock is the recent reef sandstone containing the characteristic
fossils.

Sao Miguel, Alagéas. — Pedro Antonio dos Santos of Porto de Pedras,
State of Alagédas, is one of the few men I have met who has distin-
guished between the coral and the sandstone reefs of this coast. He
informs me that there is a reef of sandstone across the mouth of the Rio
de Sao Miguel twenty-four kilometres south of Maceio.

Itheos. — At Ulheos, State of Bahia, is a reef on the beach south of
the Morro de Pernambuco which appears to be of sandstone. It laps
against the crystalline rocks of the hill at its northern end, and extends
down the beach for a kilometre or more, lying in front of the low
lands of Pontal and across the mouth of the river. (See illustration
on p. 154.)

Miscellaneous localities. — On the trip down the beach from Pernam-
buco to Maceio at several places besides those already mentioned the
beach sands were found more or less lithified. The most of these are
here specified.

At Candeias, sixteen kilometres south of the Pernambuco lighthouse,
there is a soft sandstone exposed on the beach for about three hundred
metres. It is evenly bedded, very calcareous, and so soft that the ham-
mer sinks in it. Worm or molluscan borings made in these sands while
soft are enough harder than the rest of the material to be left, on being
washed by the surf, looking like roots penetrating the beds. These soft
rocks are all within reach of the highest tides.

A little further south at the Barra das Jangadas, where the stream
enters the sea, a soft calcareous sandstone is exposed by the encroach-
ment of the stream on its northern bank. A kilometre further up this
stream on its north bank the light brown sands are partly hardened.

These beds also have the molluscan tubes crossing them.

Pedras Pretas is a small cape just north of Cape Santo Agostinho and
thirty kilometres south of Pernambuco. In the curve of the shore north
of the point there is a soft sandstone on the beach. It stands half a
metre and less above the sands, is from five to ten metres wide, and three
hundred metres long.

It dips with the beach 5°, 7°, and 8°. The sandstone is not coarse,
and it contains but few shells; there are some red iron cemented

102 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

Tertiary (?) pebbles embodied in it. The surface is partly flat and
partly etched and rounded.

The Rio Maracahype enters the sea twenty-three kilometres south of
the Cape Santo Agostinho lighthouse. Up this stream half a kilometre
above its mouth sandstone like that of the stone reefs is exposed at low
tide on the north side. It contains many fragments of calcareous Algae.

South of the Rio da Cruz and between it and the Ponta do Sao José
there are many exposures of soft calcareous sandstone on the beach. It
contains many coral fragments and broken calcareous Algae.

On the beach south of Sao José point there is much of this partly
hardened rock containing many shells.

Four hundred metres upstream from the mouth of the Rio Maragogy
(S. lat. 9° 3’) on its south side, and about sixty metres from the base of
the Tertiary (?) hills to the west, is a soft sandstone containing recent
shells.

Rio Salgado, the next small stream south of the Maragogy, has a
small reef of soft sandstone across its mouth. It is a rather patchy one,
however, and is from one hundred to one hundred and fifty metres out
from the beach. Part of this reef lies on the point just north of and
opposite Sio Bento. These reef patches are here covered with Serpulae,
barnacles, and oysters. Similar rock is exposed within the mouth of the
Rio Salgado. This looks as if it extended under the plain on which Sao
Bento stands. It contains marine shells.

One and a half kilometres south of the Barreira do Boqueirao (S. lat.
9° 9") low tide exposes a sandstone reef. It bears N. 36° E. (magnetic)
and dips gently seaward. The end examined on shore is only one of the
fragments of this reef; other fragments lie in a line more than halfway
across the embayment.

Between Sao Miguel and Rio Camarigibe (S. lat. 9° 19’) at a place
called Marceneiro the tides have undercut the bank and exposed soft
calcareous sandstones from one to two metres thick. The rock is so pure
that it is burned for lime. South of Marceneiro this bank of soft calca-
reous sandstone continues to have a height of from one to 2.5 metres.

At Riacho Doce and between that place and Garea Torta in the State
of Alagéas are several fragments of stone reefs exposed on the beach.
At one place there are blocks from three to eight metres long and a
metre thick lying on top of a coral reef and granite boulders. At an-
other place a sandstone reef sixty metres long rests on a coral reef, and
at still another there is an exposure of one hundred metres of the sand
reef alone.

-_ yi ne? * 7? Tl

©

BRANNER: THE STONE REEFS OF BRAZIL. 103

The following localities I have not seen, but they are mentioned by
Hartt :* A bit of consolidated beach of “ quartz sand cemented by car-
bonate of lime” just south of Guarapary, State of Espirito Santo (p. 62).

At Barra Secca, about fifty kilometres north of the mouth of Rio
Doce, there is a similar sandstone uncovered at low tide (p. 107).

At As Pedras, Espirito Santo, there is a similar sandstone on the
beach (p. 114). “The sandstone is exceedingly hard. Two sets of
joints — one parallel with the beach line, the other at right angles to it
— divide it into great blocks, which, in those spots where they have been
undermined by the surf, lie upset and in confusion along the edge of the
reef. Along these joints the rock is harder than between them, so that
when the surface of a block is exposed to the action of the sea, the edges
wear less rapidly than the middle, and the cracks seen on a worn surface
are oftentimes bordered by narrow ridges. . . . The waves beat terribly
against the reef, and it is badly broken up.”

1 Ch. Fred Hartt, Geology and physical geography of Brazil. Boston, 1870.

104 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.
PVE
Conclusions regarding the Forms and Structure of the Stone
Reefs.

I. THe Forms oF THE STONE REEFS.

It is often stated by writers on the stone reefs of Brazil that they are
perfectly straight. Liais himself, who saw those at and immediately
south of Pernambuco, says, ‘“‘jamais la récif ne se courbe.” To be very
exact, this is hardly true.

That the reefs do curve somewhat is shown by the illustrations and
maps given herewith. These curves, however, are always gentle, and it
is only a matter of strict interpretation of language to say that they are
not straight.

Inasmuch as the reefs are only modified sand beaches, in order to
understand their forms we must comprehend the forms of sea-beaches
generally, and also to some extent the causes of such forms as we have
along the Brazilian coast.

Sand beaches, or beaches of construction, are built up with the mate-
rials supplied by their own coast-lines : ent from headlands, washed down
from the land by streams, or washed ashore by storm waves that throw
them up from the shallow sea off-shore. The idea that has been put for-
ward that the sands of the northeast coast of Brazil may have been
brought from the west coast of Africa may safely be set aside as quite
out of the question.

Straight beaches may be produced in two ways : —

I. By the elevation of a sea bottom, or the depression of a land sur-
face that is so smooth that the new beach line, after elevation or depres-
sion, is unbroken by surface irregularities.

II. By the natural process of straightening an originally irregular,
indented, or broken shore-line by the cutting down of the headlands and
the choking up of embayments. ;

In the latter case the beach is crooked at first and its straightness
comes only with age.

1 [’ Espace Celeste, p. 546.

~

BRANNER: THE STONE REEFS OF BRAZIL. 105

Inasmuch as the beaches of which the reefs have been made have the
appearance of being accumulations or accretions, we may set aside the
probability of their having been formed by the elevation of a smooth sea
bottom and deal with the methods by which straight beaches are pro-
duced from crooked ones.

They may be considered as originating in two ways, or by a single
structural process, operating under two different conditions. These con-
ditions may produce : —

First, shore beaches, — the accumulations along the margin between
the mainland and the main body of water.

Second, of-shore beaches, or the beaches developed as spits, bars, or
barrier beaches lying parallel with the main coast-line.

The shore beach. —The form of a shore-line is determined (1) by wave
action, (2) by the resistance of the shore rocks to marine encroachment,
and (3) by the direction of inshore currents. On a coast having alter-
nate bays or estuaries and headlands, we inevitably have alternate cur-
rents and eddies next to the shore. The waves and currents attack the
headlands and throw the coarse materials cut from them into the more
quiet waters of the bays, where they sink to the bottom. If, however,
the prevailing winds drive the waves squarely against the shores, the silts
are thrown back against the inner margins of the bays, and the beaches
are built outwards by a continuous and approximately uniform process
of accretion. The tendency along such shores is, therefore, for the
beach gradually to become straight by the cutting down of the headlands
and the outbuilding of the concave beacbes. The early beaches must,
therefore, have been crooked, or more so, at least, than the later ones.
The temporary shiftings of the currents, either of the streams or of the
sea, have probably played an important part in determining the forms and
locations of the beaches and of the stone reefs.

It is evident, however, that the straight beaches are comparatively
mature ones, for it is only after the agencies mentioned have been in
operation for a long time that the broken line of the early history of the
shore becomes a straight one.}

The off-shore beach. — Off-shore beaches might be divided into those
originating as spits and those built up from the bottom as bars not
connected at the surface with the land. No sharp line can be drawn
between them, however. If the near-shore currents or the prevailing

1 Lapparent says, “the work of thesea on flat coasts is essentially constructive.”

(Traité de géologie, 2me ed. 171.) This statement, however, might be turned
about and be equally true; that is, a newly constructed sea-coast is essentially flat.

106 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY.

winds are parallel to the coast, or if they strike the coast at a low angle,
spits are built across the mouths of bays and estuaries.

The materials for such spits may be the débris derived from the head-
lands, or it may be brought down from the land by streams, or it may be
swept along the coast for miles until it falls into the quieter waters
behind or to the lee of the points where alone such spits can be formed.
When the sea is shallow the coarser materials from the bottom — the
continental shelf or shoulder — may be thrown upon the shore and swept
along to help form these spits. Sometimes the spits entirely shut off the
sea from the water of the bays, and a series of lagoons or salt lakes is
formed along the shore. In a rainy region these lakes will become
brackish, eventually fresh, and finally they will be silted up and form
marshes and, in the end; dry land. The lakes of the coast of Alagéas
are now passing through these stages, and at no distant day, speaking
geologically, they will become extinct as lakes.

Along certain coasts and about the mouths of large streams we have
off-shore beaches formed in a somewhat different manner, though they
usually merge into spits. These are sometimes called “ barrier beaches.” 4
They are long, slender bars that barely rise above the surface of the water.
In some cases they are many miles, or even hundreds of miles, in length.
Such bars, beaches, or barriers are built up from the bottom.

The explanation of barrier beaches was pointed out nearly two hun-
dred years ago by a French engineer as “The limit between the em-
bankments formed by storms at sea and those derived from fluviatile
deposits.” ? They are a part of the process of the outbuilding of ter-
rigenous agencies.

It is worthy of note that wherever these off-shore beaches exist the
range of the tides is not great, and the currents set pretty constantly in
one direction, and that in the submarine topography there is a rather
sudden dropping .off from a shallow shelf near shore to deep waters
beyond.

The straightness of such beaches is likewise noteworthy. Gannett
says that “they are very straight, running for hundreds of miles with
but slight deflections from a straight line.” @

1 N.S. Shaler, The physiography of the United States, p. 151, N. Y., 1897.

H. Gannett, Physiographic types. Typographic atlas of the United States,
Folio I., U. S. Geol. Sury. Washington, 1898.

2 Quoted from Forfait, by Elie de Beaumont, Lecons de géologie pratique,
L., p. 326.

: Henry Gannett, Topographic atlas of the United States. Physiographic
types, p. 4. Washington, 1898.

BRANNER: THE STONE REEFS OF BRAZIL. 107

There are excellent illustrations of such spits and barrier islands along
the coast of New Jersey. Island Beach is twenty miles long from Bay
Head to Barnegat Inlet, and is almost perfectly straight. Between this
bar and the shore is a broad sound, Barnegat Bay, which will eventually
silt up if the encroachment of the sea does not cut the beach away.’

Long Beach, from Barnegat City to Great Bay, is twenty-two miles
long, nearly straight, and is nowhere naturally connected with the main-
land. The beach at Atlantic City, New Jersey, is nine miles long, with
a marsh from three to six miles wide between it and the mainland?

Sandy Hook, at the entrance of New York harbor, is now a spit
thirteen miles long, measured from Long Branch to the point of the
hook. Professor Cook points out that the spit formerly * joined the
Navesink Highlands, while the Navesink River entered the Atlantic
south of the highlands. Within recent times the beach has been thrown
up outside and half a mile away, and the spit has been made into a
continuous beach from Sandy Hook to Long Branch.*

Similar barrier beaches border the coasts of North Carolina, Texas,
Mexico, Yucatan, and Rio Grande do Sul in Brazil ; in the same cate-
gory belong the /idz, or long bars, about the mouth of the Po ; others
about the mouths of the Nile and the Rhone ; the Haffs of the south
shores of the Baltic Sea; the spits of the Sea of Azov ; the long bars off
Lake Chilka, on the east coast of Hindostan, ete. In many instances
these beaches are phases of the seaward extension of deltas ; that is, the
materials have been brought down from the land by the streams behind
them. Many such beaches have lakes shut in behind them.

Another convenient illustration in Brazil itself is the low beach be-
tween Cape Frio and Itaipé peak near Rio de Janeiro. Here the low,
flat, sandy beach lies in front of a series of lakes shut in between the sea
and the lofty mountains north of them.

The rate of growth of a beach-line depends partly upon the frequency
and force of storms along the coast, partly upon the nature of the rocks
of the shores, partly upon the slope of the land, and hence upon the rate
of stream cutting, and partly upon off-shore submarine topography.

Application to the Brazilian stone reefs. — The straightness of the
Brazilian reefs shows that they are the remains either of off-shore (or

1 Vicinity of Barnegat Bay. Atlas sheet 13. Geol. Surv. of N. J., 1889.

2 Topographic map of Egg Harbor and vicinity. Atlas Sheet 16. Geol. Sury. ‘
of N. J., 1889.

8 Sandy Hook topographic sheet. U. S. Geol. Survey.

# Ann. Rep. State Geologist of N. J., 1885, p. 77-78.

108 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

barrier) beaches or of old shore beaches. If they were originally barrier
beaches we should expect to find low, flat, newly made land lying be-
tween them and the high ground of terra jirma. If they were originally
shore beaches we might expect to find them resting unconformably against
the older rocks of the headlands. This latter characteristic, however, is
not necessarily confined to in-shore beaches, but may belong to both bar-
riers and to spits formed well off the main shore.

The constant blowing of the winds on shore and the narrowness of the
continental shoulder have favored the near-shore formation of barrier
beaches along the Brazilian coast.

At Cape Santo Agostinho the reef rock laps back against the granite
rocks of that headland. Both north and south of the cape the elevated
country falls away from the shore, leaving the region near the shore flat ;
but in no case is this flat belt more than two or three miles wide, save
where streams flow in through open valleys. North of the cape the
coast is low and flat all the way to Olinda, where a headland again reaches
the sea. The stone reefs off the mouth of Rio Goyanna are well out
from the land. The Mamanguape reef approaches a Tertiary (?) hill
only at its southern end; the Natal reefs do the same. ‘The Serinhaem
reefs stand well out from the hills, though one of them is now a beach
reef. At Bahia the stone reefs were formed against steep banks. At
Porto Seguro the reef is half a mile from the hill on which Villa Velha
stands, while south of these the high land swings abruptly inland, leaving
a low, flat region to the landward of the reef. At Parahyba do Norte
the land of the peninsula of Ponta do Matto, where the recent rock is
found, is all low.

There are no lakes at present immediately behind the stone reefs,
though such lakes must have existed formerly. Lagéa de Almada, in
the State of Bahia, is a fresh-water lake, believed by Spix and Martius
to have been formerly an arm of the sea. Stone reef rocks are said to be
found in the vicinity of this lake, but no mention is made of the geo-
graphic relations of these rocks to the lake." There are no barrier
beaches along the northeast coast of Brazil now except those of coral.

It is a noticeable characteristic of the shore forms behind the stone
reefs, that wherever there is a break in the reef, the new shore-line falls
away, forming an indentation like that just north of Gaibt (see p. 70).

Structure of the stone reefs.— The structure here considered relates
only to gross structure, —the bedding and the relation of the beds to

1 J. B. von Spix und C. F. P. von Martius, Reise in Brasilien, II., p. 684-685.
Miinchen, 1828.

i a a a 2

BRANNER: THE STONE REEFS OF BRAZIL. 109

each other. The composition is treated under the head of “ Consolida-
tion” in Part VI.

The structure of a stone reef in cross-section is well shown in the
accompanying figure, which was first published by Hartt in 1870.

Tigh Water

sas en

Sea
LowWater

Na wwe e eee

Fic. 65. Theoretic section across a stone reef. — Hartt.

The same structure is shown in Wagoner’s section of the Porto Seguro
reef. (See p. 96.)

In the undisturbed rocks the dip is almost invariably seaward, and
the angles are the low angles common to beach sands. I have often
measured the slopes of the beaches, and in a few instances I have been
able to measure the dips of the reef rocks. At Piedade, a village on
the coast a few kilometres south of Pernambuco, the rocks of the stone
reef dip at angles varying between 4} and 64 degrees ; the beach sands
at the same place dip at angles varying between four and five degrees.
At Venda Grande, just south of Piedade, the beach has a slope from
four to five degrees. I have measured sand slopes as high as 37°, but
these were cases of false bedding. The steepest beach noted on which
the waves played was at the mouth of Rio Sapucahy, where it had a
slope of 11°.

At Pedras Pretas, the small cape just north of Cabo Santo Agostinho,
a small stone reef has dips varying between five and eight degrees. The
beach sands have similar dips. The stone reef of Pratagy shows its
seaward dip well, but no angles were measured. Some of the photo-
graphs of the Mamanguape reef also show the seaward dip of the rocks.
Occasionally one sees strongly marked false bedding in the reef rocks.
Cases of the kind have been noted on the Mamanguape reef. At Rio
Grande do Norte the reef, as seen from the lighthouse on the reef, shows
the beach structure fairly well.

Mention should be made here of the statements of Liais that the reef
rocks are sometimes vertical. As pointed out in Part V., no cases are
known to the writer in which the reef rocks are vertical or have very
high dips except where certain blocks have undermined and have
tipped up on one side.

110 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

Considered in relation to underlying rocks, the structure of the stone
reefs is best understood from the results obtained by the holes bored in
the Pernambuco reef in 1874 by Sir John Hawkshaw. The following is
the record of the deepest hole* put down.

REcorD oF BoRING ON THE PERNAMBUCO REEF.

METRES.
Reefirock; hard ssc. OR ee ee
White sand s-.. 20-2) cotta, Saleh oe eee
Shells’? 2 ee a ee oe
Gray sand. (ss ia 1 ae ero
Broken rock SS 4 IG a Se TG
Dark sand’. te).0 ert Gao MIN Stee ee 1
Mottled: clay: 4 <) 2 2575, es ioe
Yellow clay gs hae Risen ead eel a ae a
Gray.Sand. 0. oie, 1 segs) Me penen nara a
White'sand 270.4% 085 J) thet Fey ee

Other holes put down in the reef show that the surface rock is underlain
by sands, shells, and clays, but there is no regularity in the sequence of
these materials.

Conclusions. —'The stone reefs are nearly, but not quite, straight.
The bedding of the materials dips seaward at the same angle as ordinary
beach sands. The hard rock of the reef is only three or four metres
thick. The underlying materials are sands, shells, and clays without
recular sequence. The process of formation, the character, and the
structure of the reefs show that they are ancient beaches hardened by
lime carbonate, while their straightness shows that they are forms of a
mature beach-line fixed and made permanent by the process of consoli-
dation pointed out in Part VI, pp. 171-198.

1 Melhoramento dos portos do Brazil, p. 15. Rio de Janeiro, 1875.

a

BRANNER: THE STONE REEFS OF BRAZIL. dw Bg

V.
The Hlevation and Depression of the Northeast Coast of
Brazil.
PAGE PAGE
Changes of the reefs within his- Riosbapadosee) «io. yet tuyey de
GONICHTIMES > fea 1 111 Choked embayments . . . 13
Changes within recent geologic Depressed valleys . . . 13
Perigdsr:. =. 5 ee ee LS The case of Rio Sao Fran-
Views of former sae oo LMS CISCOMMEE it stlarers: F20/241 145
Schistose structure of reef sland sige ememicied cies 4-72 44
rocks ..; a eg were eb Ofi-shorerclays! y...1 0. 1. 144
Dip of the reef rocks fuey ee LD Buried rock-channels . . . 145
Reef rocks above high tide . 120 Additional views of depres-
Lakes near the coast . . . 121 SOW 9 6 eed cata tO
Fixed dunes of the coast. . 121 Evidences of elevation Maite eh a 148
Islands joined to mainland . 122 Elevated sea beaches . . . 148
Straightening of the coast- Elevated sea-urchin burrows 159
Ne} ies 124 Death and decay of the coral
Comparative pares of ele- Ee Ge Semon le 159
vation and depression . . 125 Time relations of the pie aes
Effects of elevation. . . . 125 and depressions . .. . 162
Effects of depression . . . 125 Influence of the coral reefs . 164
Forms on a stationary coast 127 Influences of the mangues,
Application to’brazil 2. 5. 127 hy Acinthseessats tt ee LOT
Evidences of depression. . . 127 Origin of the coast sands . 167
Opentbaysiers-m lacs hea ee oS Conclusions regarding coast
Coastilakesit. 0.00 9-36 129 changes (ae eew sabes 8 ae. 109

CHANGES OF THE REEFS WITHIN Historic TIMEs.

There are, perhaps, but few coasts of considerable length on which
there are not evidences of both elevation and depression. Along the
west coast of North America, for example, wave-cut terraces upon the
slopes of the hills and mountains near the coast show that there have
been several recent elevations of the land, while well-defined submerged
valleys,’ the distribution of the fish faunas in fresh-water streams,
and the relations of fauna and flora of the islands off the coast to those
of the mainland show that there have also been recent depressions.

Observations of others. — Humboldt and Darwin show that there has
been a recent elevation of the northern end of the South American con-

1.George Davidson. The submerged valleys of the coast of California, U. S. A

and of Lower California, Mexico. Proc. Cal. Acad. Sci., 3rd ser., Vol. I., p. 71-103,
and plates. San Francisco, June, 1897.

112 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

tinent,’ while the dendritic fjords and islands along the coast from
Tierra del Fuego to south latitude 41° show that there has also been a
comparatively recent depression in that region.” A late paper by Pro-
fessor Gormaz of the University of Chile directs attention to the fact
that while there are evidences of elevation along that coast, certain
localities show equally satisfactory evidences of depressions, even within
the historic period.®

But the localities mentioned by these writers are far from the region
with which we have to deal. The question with which we are chiefly
concerned is whether there have been changes of level within historic or
geologically recent times along the northeast coast of Brazil, and whether
such changes, if they did occur, bear directly upon the existence and
forms of the stone and coral reefs of that region.
We must also keep in mind the great length of the Brazilian coast-line,
about sixty-four hundred kilometres from the northern end at the
mouth of the Oyapoc on the frontier of French Guyana (5° 10! north
lat.) to the frontier of Uruguay at the mouth of Rio do Chuy in south
latitude 33° 45’. As in other parts of the world, where so long and so
nearly straight a coast-line is concerned, the orographic movements over
this distance have not necessarily been at the same rate or even in the

same direction.

The evidence of a geologically recent elevation of the southern coast
of Brazil is fairly satisfactory, while still further south in the Argentine
Republic it is remarkably impressive, and considerable elevations are
reported to have taken place even within the historic period. Many
facts concerning the southern end of the continent are given by Darwin
in his “ Geological Observations,” Chapters VIII. and IX.,* and by J. B.
Hatcher in his paper upon the geology of southern Patagonia.’ These
facts show that the change of level affected the east coast for a distance

1 Darwin’s Geological observations, Chap. IX.

2 Professor Shaler notes, however, that the submarine cutting of ice may be
responsible to some extent for the form in this case. Bull. Geol. Soc. Amer., 1894,
VL, p. 162.

8 Francisco Vidal Gormaz. Depressions and elevations of the southern archi-
pelagoes of Chile. Scottish Geog. Mag., Jan., 1902, p. 14-24.

4 Dr. Friedrich Gustav Hahn published at Leipzig in 1879 a paper upon the
elevation and depression of coasts. (Untersuchungen iiber das Aufsteigen und Sinken
der Kiisten) —in which he gives a brief résumé of the evidence of the upheaval of
the southern part of Brazil (pp. 93-97). This paper, however, in so far as it relates
to the coast under consideration, contains only the facts given by other authorities.

5 J. B. Hatcher. On the geology of southern Patagonia. Amer. Journ. Sci.,
Noy., 1897, CIV., p. 845-350.

i ii

BRANNER: THE STONE REEFS OF BRAZIL. £13

of nineteen hundred kilometres, that the elevation has been greater
toward the south and west, and that it diminished northeastward. In
southern Patagonia’ the elevation is given as four hundred feet (one
hundred and twenty-two metres) ; in the La Plata region it has been
one hundred feet (thirty metres). Darwin, however, does not maintain
that the elevation of the Cordillera and that of the La Plata provinces
took place at the same time.?

Although Darwin’s discussion refers chiefly to the La Plata region
and to the country south and west of there, he mentions also evidences
of the elevation of the coast of southern Brazil at Santos and near Cape
Frio.’ Bardo de Capanema states that the city of Laguna in the State
of Santa Catherina “stands upon a dark alluvial deposit densely packed
with shells which have not been carried there, for I found oyster shells
grown upon a granite cliff half a metre above the present level of the
city and something more than two metres above the highest water-mark
of the harbor.” 4

The evidences of the elevation of the coast near Rio de Janeiro con-
sist of recent shells in sands now above tide, about the Bay of Rio; re-
ported sea-urchin holes bored in the granite rocks at the base of the
Pao d’Assucar and now above the reach of the tides ; similar holes at
Villa Velha; and marine erosion lines beyond the reach of tide-water at
Victoria.° Herbert Smith mentions® one place where recent shells are
found four metres above high tide on the Bay of Rio de Janeiro.

For the coast north of Espirito Santo but little evidence has been
published showing changes of level. Some very general statements have
been made and theories advanced, but the ouly specific evidence pub-
lished on the subject consists of two papers by Richard Rathbun refer-
ring to the elevated beach at Porto Santo in the Bay of Bahia.

This leaves a long coast-line of whose vertical movements little or
nothing is known. And it should be remembered that Victoria, where
the evidences of changes are satisfactory, is four hundred and forty
kilometres from the stone reef at Porto Seguro, the southernmost of
the stone reefs, fourteen hundred and fifty kilometres from Pernambuco,

1 Darwin’s Geological Observations, p. 218.

2 Geological Observations, ed. 2, p. 210-211.

8 Geological Observations, p. 193.

* Mittheilungen aus Justus Perthes’ Geogr. Anstalt von Dr. Petermann, 1874,

. 280.
: ® Ch. F. Hartt. Geology and physical geography of Brazil, p. 35, 71-73.
6-H. H. Smith. Do Rio de Janeiro a Cuyabé. Notas de um Naturalista, p.

10-11. Rio, 1887.
VOL. XLIV. 8

114 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

and two thousand and ninety kilometres from the northernmost reef
at Ceara.

Hawe there been changes within the historic period ?— Several writers
have expressed the opinion that the northeast coast of Brazil has been
elevated recently. It is not always clear whether they mean ‘recently ”
in the historic or in the geologic sense. Capanema, however, speaks of
a recession of the sea at one place at the rate of “ten fathoms in thirty
years.” *

This must necessarily be taken to mean an elevation during the
present century.

The point at which this particular elevation is said to have occurred
is Aquiraz in the State of Ceara, four leagues southeast of the city of
Ceara and half a league from the coast. It is off the ordinary routes of
travel, and as the writer has not visited the place and knows of no ac-
count of it by other observers, we can only judge it by what is known
of other places on this coast.

Inasmuch as the sandstone reefs of northeast Brazil have attracted the
attention of navigators and travellers since the earliest times, and as
these reefs are of great importance to commerce, and inasmuch as any
elevation or depression of the coast would immediately produce notice-
able effects upon them, they afford an excellent. means of judging
as to whether or not any such changes of level have taken place since
the discovery of Brazil.

It was to have been expected that so remarkable a natural phenomenon
as the sandstone reefs of Brazil would arrest the attention of the early
navigators. The oldest accounts we have of the reefs relate to those at
Porto Seguro and at Pernambuco.

Pero Vaz de Caminha, one of the companions of Cabral, the discoverer
of Brazil, was the first to make mention of the reefs, — the one at Porto
Seguro, where Cabral landed in the year 1500. He merely mentions it,
however, as a “‘reef having a very good and secure port inside of it.” ?

Pero Lopes de Souza was at Pernambuco in 1530; he mentions
the reef at that place, the one near Cabo Sto. Agostinho, and one at

1 Trabalhos da Commissio Scientifica. I. Introduccio, p. exxxvii. Rio de
Janeiro, 1865.

2 Carta de Pedro Vaas de Caminha a El Rei D. Manoel. Colleccao de noticias
para a historia e geografia das nacdes ultramarinas que vivem nos dominios Portu-
guezes. Tom. IV., No. III., p.180a. Lisboa, 1826.

Corografia Brazilica de Manoel Ayres de Cazal. I., p.12-384. Rio de Janeiro, 1817.

Revista do Instituto Historico e Geographico do Brazil, 1877, XL., Pt. II., p. 18-37.

a

BRANNER: THE STONE REEFS OF BRAZIL. 115

Sao Miguel on the coast of Alagéas, but he gives no description of
them.

Gabriel Soares de Souza, who lived in Brazil from 1570 to 1587, gives
the earliest statements regarding the nature and extent of the reefs,
though he makes no distinction between stone reefs and coral reefs.
He notes, however, that the reef at Bahia was covered at high tide.
There can be no doubt that he refers in this case to the sandstone reefs,
for he says that the rock was used for building purposes in the city of
Bahia, —a fact to which many of the old houses still bear witness. He
also says that the reef rock is made of sand, and that it often contains
oyster and other shells and pebbles.?

In 1625 Purchas speaks of the reefs at “ Fernambuquo” as “ Clifts
as if it were made by Bricklayers, no higher in one place than in
another, but all euen.” ®

The cuts of the Pernambuco reef reproduced by Varnhagem were first
printed in 1630,‘ and appeared also in the original of Dapper’s “ Die
Unbekante Neue Welt,” in 1671.8

Joannes de Laet, one of the directors of the West India Company,
who lived at Pernambuco from 1630 to 1636, published a map show-
ing the reefs south of Cape Santo Agostinho and at Rio Grande do
Norte.®

1 Diaro da Navegacio da armada que foi a terra do Brazil em 1530 sob a capi-
tania-mor de Martim Affonso de Souza. LEscripto por seu irmao Pero Lopes de
Souza, p. 14-15. Lisboa, 1839.

2 Noticia do Brazil. Published anonymously at Lisbon in 1825 by the Academia
Real das Sciences as Vol. III, Pt.I., of the “ Colleccao de Noticias para a historia,”
ete.

Tratado descriptivo do Brazil em 1587. Por Gabriel Soares de Souza. Revista
do Instituto Historico e Geographico do Brazil, 1851, XIV., p. 25, 27, 31, 33, 354.

8 Purchas, his pilgrimes, in five bookes. Vol. IV., Chap. VIL. p. 1238. London,
1625.

* Historia geral do Brazil. Pelo Visconde de Porto Seguro, 2a. ed., Vol. I. opp.
p. 852 and 504. Rio de Janeiro (circa 1875).

5 Dr. O. D(apper). Die Unbekante Neue Welt. Amsterdam, 1673. The orig-
inal was written in Dutch by Arnoldus Montanus, and was published at Amster-
dam in 1671. When translated into German, the book was ascribed to Dr. O. D.
(Dr. O. Dapper) in whose collection it appeared. See bibliographical and histori-
cal essay on the Dutch books and pamphlets relating to New Netherland. By
E. M. Asher. Amsterdam, 1854-67, p. 28; also Les Hollandais au Brésil. Par
P.M. Netscher, p. xvii. La Haye, 1853.

6 Historie ofte Iaerlijck Verhael van de Verrichtigen der Geoctroyeerde West
Indische Compagnie Zedert haer Vegin tot het eynde van’t jaer 1636. Leyden,
1644.

116 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

Elsewhere he gives a brief description of the stone reefs, states that
they are exposed at low tide, and that they are broken here and there.!

William Piso, who lived at Pernambuco during the Dutch occupancy
under Maurice of Nassau from 1637 to 1644, says of the reef at that
place that “its height is such that it is rarely covered by the highest
tide.” ?

Caspar Barleus, the first edition of whose work was published in
1647, gives Piso’s description of the reef, but he gives besides a plan of
the reef and of the city of Pernambuco, and a view of the reef taken
from the south end and looking toward the city and the northern end
of the reef.2 But Barleus was never in Brazil, and his information was
all at second hand, probably from Piso.

Pierre Moreau, who lived in Brazil two years, was at Pernambuco
about 1648, and says of the reef that it is “as high as a pike or more,
uncovered when the tide is out, but not otherwise because it is all
covered.” #

Other early references to the reefs will be found in the annotated
bibliography forming part of this paper under the names of Dapper,
Angelo, Nieuhof, Gioseppe de 8S. Teresa, Ayres de Cazal, and Koster.

These writers differ somewhat in regard to the height of the reefs,
some of them stating that they are only uncovered at low tides, and
others that they are rarely covered by the highest tides. These differ-
ences, however, are precisely the kind of differences of opinion one may
find to this day in regard to the height of the reefs among people per-
fectly familiar with them. And it is not to be supposed that the old
writers spoke with any unusual precision about this matter.

During the spring tides here and there points remain uncovered at
high tide, especially if there be but a little wind. At some places,
however, where the reef has been undermined, and huge blocks of stone
have been tipped on end, these may not be covered even at the highest
tides except by the surf dashing over them. There is such a block on

1 Le Sieur Ien de Laet, d’Anvers. L’histoire du nouveau monde, p. 530, 5383.
Leyde, 1640.

2 Gulielmi Pisonis — de Indae utriusque Re naturali et Medica, p. 6-7.
Amsterdam, 1658.

3 C. Barleum. Res Brasilie, imperante Illustrismo. D. I. Mauritio Nassovie,
etc., Principe. Accedit G. Pisonis tractatus de Aere, Aquis et Locis. (This work
is commonly known as “Rerum per Octennium in Brasilia.”) Editio secunda,
Clivis, 1668. (First ed. Amsterdam, 1647.)

* Pierre Moreay. Histoire des derniers trovbles dv Brésil entre les Hollandois
et les Portvgais, p. i, Paris, 1651.

BRANNER: THE STONE REEFS OF BRAZIL. dy:

the Rio Formoso reef, where it is popularly known as the “ Pedra de
Nossa Senhora.” At ordinary high tide the reefs all along the coast
appear for the most part as a line of breakers with black points of
rock now exposed and now covered by the surf. Whether the waves
break over the reef during neap tides depends much on the winds
blowing on shore. At low tide these reefs almost invariably stand out
like black walls surf-beaten on the seaward side.

If any one acquainted with the reefs should say that they were entirely
covered at high tide, there would be some one else equally well ac-
quainted with them to contend and to prove that they were never
entirely covered.

But as long as the unbroken reef rocks do not rise beyond the reach
of the highest storm tides we are not justified in assuming that they
have been elevated.

There has been a certain apparent recession of the sea, due, however,
not to the elevation of the land, but to the silting up of the marshes,
estuaries, lakes, and mangrove swamps behind the reefs.

In 1881 MM. Victor Fournié, sometime city engineer of Pernambuco,
and Emile Beringer, his assistant, published a “ mémoire sur le port du
Recife”? accompanied by a carefully made (in 1876) map of Pernam-
buco and its environs. On this same map is an overprint of the best
map it was possible to compile from those made by the Dutch, of the
same region, during the first half of the seventeenth century. This map
is the most important document we have of the kind bearing upon coast
changes within historic times. It shows that since these early maps were
made, channels then open have filled up, others have been much nar-
rowed, and large areas, then either swamps or quite under water, have
become dry lands and have been built up with houses. .M. Beringer
remarks (p. 20), “ The Sao José quarter was a great marsh covered at
high tide,” while the width of the channel at the Recife bridge was
nearly half as great again as it was in 1876.

Conclusions. — The statements here cited and the facts given, some of
them dating back to the first half of the sixteenth century, — more than
three hundred years ago, — suggest, if they do not show conclusively,
that there has been no striking, or even, to the ordinary intelligent
observer, perceptible change in the reefs from that time to this, while
the channels then open behind them have been gradually filled up. If,
then, there has been an elevation or depression of this coast within the

1 Bijbladen van het Tijdschrift van het Aardrijkskundig Genootschep. Am-
sterdam, 1881.

118 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

historic period it has been very slight indeed. The recession of the sea
at the rate of “ten fathoms in thirty years” as given by Capanema
is quite out of the question.

CHANGES WITHIN REcENT GEOLOGIC PERIODS.

Views of former writers. —It is somewhat remarkable that all those
who have seen this coast and expressed views about its history have
thought it to have been elevated within recent geologic times. These
writers are, Baraio de Capanema,) Liais,? Hartt,? and J. Clarke
Hawkshaw.*

Thomaz Pompeo de Souza Brasil, in his valuable Ensaio Estatistico da
provincia do Ceara (p. 49), says that at the Barra do Pacoti in Ceara, “as
in Bahiaand Rio de Janeiro, proofs are seen of the elevation of the coast,”
but he does not say what these proofs are.

It is but fair to these writers that their views and their reasons for
holding them should be given. On the other hand, it is but just to
recall the fact that a theory becomes really important only when it is
supported by adequate evidence.

I shall therefore give very briefly what the authors cited regard as
evidence of the geologically recent elevation of the coast, and at the same
time my own reasons for looking upon the bulk of this evidence as
unsatisfactory.

Hartt presents tangible evidence of elevation along the coast about
Rio de Janeiro, and for some distance north of there. This evidence
consists of sea-urchin holes, and old water-lines above tide-level on the
island of Maricas, near Rio, on the great conical hill at Victoria, and on
the island of Sant’ Anna.

In the article cited Hawkshaw speaks of conclusive signs that the
coast has recently risen ” and of “ unmistakable signs . .. of a recent ele-
vation of the coast.” but he does not say what these signs are.

The following are adduced by Liais as facts in support of the elevation
theory :—

1. The schistose structure of the reef rocks.

1 Trabalhos da Commissio Scientifica de Exploragao. 1. Introduccao, p.
exxi, exxxvii. Rio de Janeiro, 1865.

2 E. Liais. Climats, géologie, ete. du Brésil, p. 256-261. Paris, 1872.

E. Liais. L’Espace Céleste, ed. 2, p. 545-548. Paris (1881?).

Compt. Rend., 1860, L., p. 762-763.

3 Geology and physical geography of Brazil, p. 35, 36, 42, 71-72, 344.

* Quar. Journ. Geol. Soc., 1879, XXXV., p. 241-245.

BRANNER: THE STONE REEFS OF BRAZIL. 119

2. The inclination of the reef beds.

3. The elevation of the stone reefs beyond the reach of the high tides.
(Capanema speaks of the recession of the sea in the same sense.)

4. The lakes along the coast. (Capanema refers to lakes shut off by
sand-banks. )

5. The fixed dunes of the coast.

To this list may be joined two additional points held by Capanema;
namely : —

6. Islands joined to the mainland.

7. The conversion of a deeply indented coast-line into a weakly in-
dented one.'

It may be said at the outset that whether there has or has not been
an elevation of the coast in question, in my opinion the facts to which
appeal is made in these cases are either not facts at all, or else they do
not admit of the interpretations given them.

These poiuts will be briefly considered in their order.

1. The schistose structure of the reef rocks.—It is presumed that the
idea here is that schistosity would have been produced by orographic
movements. However that may be, in the many kilometres of stone
reef examined by the present writer, what is commonly regarded as
schistose structure has not once been observed in the reef rocks. In
places the rocks sometimes contain mica, and are therefore somewhat
foliated, and it seems probable that this foliation may have been re-
garded by Liais as schistosity. The mica that causes the foliation was
deposited with the sand.

2. The dip of the reef rocks. — Liais considers the angle of slope of the
beds (op. cit., p. 545) as having been produced by orographic disturbance,
the inference being that the strata were originally horizontal. It is true
that the beds of the rock reefs do have a dip varying between two and
twenty degrees, and in a few cases running a little higher. But the dip
is usually low and uniform and invariably toward the sea; it is simply
the bedding of the beach sands of which the reefs are made. Such dips
may be seen in the wet sands of the present beaches.? I have lately
made notes upon the angles of the wet sand uncovered at low tide along
the coast of Pernambuco and Alagdas. These angles run as high as
twenty-four degrees in false beds. A newly formed delta in the Una

1 Mittheilungen von Dr. Petermann, 1874, p. 230.

2 A. de Lapparent. On this subject see Traité de géologie, p. 173, 175. Paris,
1885.

L. Elie de Beaumont. Legons de géologie pratique, Vol. I., p.226-227. Paris, 1845.

120 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

had a false dip on the steep front varying from 34° to 37°. An un-
usually steep beach up and down which waves were running at the mouth
of Rio Sapucahy had a slope of 11°.

Liais states, however, that these reef beds are sometimes vertical.
This is true, but in no case has the writer seen a reef rock in place in a
vertical position. The hard reef rocks rest upon soft sands; it fre-
quently happens that the reef is undermined by currents, and huge
blocks of stone falling in the soft sands are left tipped about in various
positions and even standing on end.

3. Reef rocks above high tide. — Whether rock above high tide can
be accepted as evidence of elevation depends on how the rock was
formed. M. Liais speaks of the reef rock as having been formed beneath
the sea.’ If that were the case, the reasoning might pass, but it is doubt-
ful, to say the least. The toppling over of a large mass in the manner
just referred to sometimes lifts one end out of the water and beyond the
reach of high tide. Besides such cases there are instances of the harden-
ing of beach sands beyond the reach of the tides. This hardening may
be caused either by spray being blown by the wind several metres
higher than the tides rise, or it may be produced by rain water dissolving
the lime from the upper layers of sand and depositing it again lower
down. ‘There are many excellent illustrations of this hardening of sands
far above tide on the island of Fernando de Noronha? and at other places
in the world, though the writer does not remember to have seen any on
the Brazilian mainland.

The case’of the recession of the sea cited by Capanema occurs in the
State of Ceara. He says of it: “In Ceara the elevation has been con-
siderable near Aquiraz in a place where the sea has receded ten fathoms
in thirty years, and to this the inhabitants cannot apply their favorite
explanation — the accumulation of sand— for the poles have not been
covered.”® The italics are mine. He does not state whether or not
the land uncovered is hard rock or soft sands and clays, and in order
to judge of the meaning of such phenomena it would be necessary to

1 L’Espace Céleste, p. 545, 548.
2 J.C. Branner. Geology of Fernando de Noronha. Amer. Journ. Sci., 1889,

XXXVL, p. 160-161.

J. C. Branner. The zolian sandstones of Fernando de Noronha. Amer. Journ.
Sci., 1890, XX XIX., p. 247-257.

H. B. Woodward. The Geology of England and Wales, ed. 2, 1887, p.546-7, 550-1.

T. McK. Hughes. Ancient beach and boulders near Braunton and Croyde,
Quar. Journ. Geol. Soc., 1887, XLIII., p. 657-670.

8 Op. cit., p. CXXXvii.

BRANNER: THE STONE REEFS OF BRAZIL. 121

know this, and also to know the angle of the newly exposed surface.
It is certainly not to be supposed that a vertical recession of ten fathoms,
or anything approaching it, has taken place in thirty years.

4, Lakes near the coast. — Liais’s idea seems to be that the lakes
near the coast are produced by elevation and that their basins are the
lower portions of the former sea bottom, while Capanema speaks of the
shutting off of Jakes by sand banks— apparently understood to be
banks of submarine origin.

There can be no doubt that lakes might be formed in this way ; there
may be a question as to whether the lakes of the Brazilian coast have
been so formed. This question will be considered later.

5. The fixed dunes of the coast.— Liais assumes that an elevation of
a coast on which sand dunes had been forming would put a stop to the
beach supply of sand, and that the dunes would for this reason cease to
move.

Where it is a question of small vertical elevation, such a result is not
to be expected from such a cause. When dunes are once set going over
large areas no new supply of sand is necessary to keep them in motion,
This is too well known to require discussion. In northern Nebraska,
a thousand miles from the sea-coast, are extensive areas covered by shift-
ing sand dunes. Many of the great deserts of the world, such as the
Colorado desert, the Sahara desert, the Mojave desert, and the deserts
of the lofty arid regions of South America, bear witness to this fact.

If it be assumed that the case is different on the coast-line where the
dunes occupy a narrow belt, then it comes to be a question as to whether
the dunes along the Brazilian coast are or are not now in motion. Asa
matter of fact the dunes of this coast, with certain exceptions, are not
stationary, as the writer knows both from personal observation and from
the statements of other trustworthy writers. The dunes are moving
along the coasts of Bahia, Sergipe,' Alagéas, Rio Grande do Norte,
Ceara, and Maranhao. In these states the writer has seen many miles
of dunes, and they are known to every one who has travelled much along
the coast. Hartt mentions them in Bahia,? Sergipe, Rio Grande do
Norte, and Cearé. Koster also mentions those of Rio Grande do
Norte.? In the last-named state the dunes stretch for miles along the

1 J. C. Branner. The Cretaceous and Tertiary geology of Brazil. Trans.
Amer. Phil. Soc., XVI., p. 375. Philadelphia, 1889.

2 Geology and physical geography of Brazil, p. 845-346 ; 355; 383; 394; 455;
458.

8 Henry Koster. Travels in Brazil, 2d ed., Vol. I., p. 102. London, 1817.

122 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

coast both north and south of Natal, and at this last place efforts have
been made by the government for years to prevent the dunes from
filling up and destroying the harbor.

North of the village of Bahia Formosa moving sand dunes form the
coast as far as the mouth of Rio Cunhaht. Some of these dunes
rise to a height of sixty metres and are now blowing inland. Ordi-
narily they are about twenty metres high, and the sand is blown inland
over a caatinga forest.

A score or more of instances might be given of the movement of the
dunes of the coast of Rio Grande do Norte. These, however, must
serve, especially as the validity of the argument based upon their being
fixed is not recognized.

Pompeo de Souza Brasil observes that the dunes of Ceara are always
in motion, ‘so that the coast is ever changing its aspect.” In some
places he says the dunes extend for leagues into the interior and even
close the mouths of streams and turn them into lakes.?

Capanema says the Ceara dunes are sometimes three hundred palms
high ? and Hawkshaw ® notes that they “stretch for miles on each side
of the city of Ceara,” while at Maranhao, Ponta d’Areia, ‘‘the soldiers of
the fort have much difficulty in keeping themselves from being en-
gulfed ” in sand.

“A curious circumstance of this part of the coast (northeast Brazil)
is that all the western sides of the river mouths are covered with vege-
tation and mangrove swamps, while the eastern sides are barren sand
wastes. This is caused by the constant action of the east wind on the
dunes ; the sand is driven toward the west until it comes to a river and
there it falls.” +

6. Islands joined to the mainland (Capanema).— A study on the
eround of the physical geography of the Brazilian coast makes it plain
that former islands have, within geologically recent times, been joined
to the mainland. But such joining cannot alone be accepted as evidence
of an elevation; the question is, how was this joining brought about ?

If we imagine the Pernambuco coast elevated an amount equal to or

1 Pompeo de Souza Brasil. Ensaio estatistico da provincia do Ceara. L., p. 10-11.
J. E. Wappeus. A geographia physica do Brasil, p. 15. Rio, 1884.

2 Trabalhos da Commissio scientifica de Exploragio. I. Introducgio, 1862, p.
CXXXVl1-Vll.

8 Melhoramento dos portos do Brazil, Relatorio de Sir John Hawkshaw, p. 80-
81,91. Rio de Janeiro, 1875.

4 J. E. Wappeus. A geographia physica do Brazil refundida, p. 15. Rio de
Janeiro, 1884.

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124 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

somewhat greater than the depth of the water between the mainland
and the island of Santo Aleixo, that island would of course be joined
to the land by this process of elevation.

But islands are not joined to the mainland solely by this process of
elevation ; they may be united by a process of silting up, by the build-
ing out of spits or accumulations over an intervening shallow bottom.
A convenient illustration of what I mean is furnished by the Pao
d’Assucar at Rio de Janeiro. The Pao d’Assucar was not long ago an
island having a shallow water passage between it and the Morro de
Babylonia just where the Escola Militar now stands. The waves, how-
ever, have thrown the coast sands back into this passage until it has
been completely filled up and the Pao d’Assucar has thus been joined
to the mainland.

It will be shown later that there has been a depression of the north-
east coast of Brazil. Before that depression took place there was a
valley southwest of Cabo Santo Agostinho opening broadly toward the
sea. In this valley were a few isolated hills left by the erosion of the
Tertiary highlands. When the depression occurred, the bottom of this
valley went beneath the water, and these isolated hills were left as islands
in the big bay. In the course of time this entire bay has been filled
with sands and silts and turned into dry land, and in the process these
former islands have been united to the mainland.

At Ilheos, State of Bahia, a rocky hill at the mouth of the harbor,
known as Morro de Pernambuco, is joined to the mainland by a sandy
neck that has the appearance of being a spit lately built in. It is evi-
dent therefore that while islands have been joined to the land, this
joining cannot alone be accepted as evidence of an elevation of the
coast, but may indeed come from a movement in quite the opposite
direction.

The chief objection to the statement by Capanema as it stands, how-
ever, lies in the absence of specified cases.

7. The straightening of the coast-line (Capanema).— The line of
reasoning in the case of the straightening of the coast-line is not indi-
cated by Barao de Capanema, but it is probably meant that on account
of the sea bottom being less rugged and less scored than the land sur-
face, an elevation would at once yield a comparatively even beach-line,
while a depression, owing to the unevenness of the land, would give a
very crooked one. But a coast-line may be straightened by quite
another process ; namely, the process of destructive attack by the sea.
The facts presented hereafter appear to warrant the belief that the

BRANNER: THE STONE REEFS OF BRAZIL. 125

ancient indentations of this coast have been obliterated by time and
the sea,

Comparative effects of elevation and depression. — The relations of
the reefs to the shores and to the coast topography makes it necessary
to deal with the topographic forms of the reefs and to understand by
what processes and in what order they originated.

The general effects of elevation on any coast will be considered first,
and afterwards the effects of depression, and then by comparing the lit-
toral forms thus produced with those of the Brazilian coast the writer
will try to determine by which of these movements its present features
have been produced.

Liffects of elevation. —If any coast were considerably and abruptly
elevated the old beach-line would form a terrace, the old undercut shores
would be marked by an incised line produced by the former work of the
waves, the coral reefs of the region would be exposed, the polyps killed,
and the remains of marine animals, especially the Mollusca, would be left
strewn across the newly raised land. The streams would have their cur-
rents increased about their former mouths and would immediately begin
to cut into their rock bottoms and to make deep, steep-sided channels.
If there were partly enclosed bays or lakes along the former shores, their
outlets would cut deep channels back into the lakes and they would be
drained at once. Inasmuch as the irregularities of the land, on account
of subaerial erosion, are more marked than those of the sea-bottom, a
depression would, as a rule, yield a more indented coast-line, while an
elevation would yield a coast with but few harbors.

An elevation of three or four metres on this Brazilian coast would pro-
duce a peculiar effect upon the stone reefs; the waves would undermine
the reefs, for as has elsewhere been shown, they are hardened only to
this depth, and they would break into angular blocks and strew the
newly made beach with their remains.

Effects of depression. — If a considerable depression took place on a
sea coast, the valleys near the coast would be flooded and would become
bays, narrow estuaries, or fjords, according to the shapes of the valleys.
In general, the coast-line would have the dentritic form suggested by
the coast of Maine more or less marked, according to the relief of the
region before the depression took place.

This is so universally true that Dr. James Geikie in his recent work
upon “ Earth Sculpture” states (p. 328) that, “All highly indented
coast lines are evidence that the land is sinking or has recently sunk.”
Lord Avebury, in his “Scenery of England,” observes (p. 125) that,

126 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

“When the land is sinking . .. the drowned river valleys make the
coast irregular and complicated.”

Another characteristic of recently sunk coasts is that fringing islands
usually abound along them. Immediately following a depression sedi-
ments brought down by the streams and washed by the waves from the
promontories and fringing islands silt up the bays and lower stream
channels, and only such channels are left as the tides are able by their
scouring action to keep open. At first the tide flows further inland and
there are many harbors on the new coast, but in the course of time the
silting up of the estuaries crowds the tide back to the open coast-line.
If the depression goes on more rapidly than silting, the tides extend
further and further inland ; but if silting and the constructive work of
the sea are more rapid the tides are kept back. Depression brings
within the reach of the waves a new surface and adds greatly to their
cutting power, and consequently large quantities of silts are produced.
If the prevailing winds blow on shore, as they do on the Brazilian coast
all the year round, the heavier silts cut from the headlands are thrown
back into the bays rapidly, the beaches of sand extend seawards, the
closing of the mouths of streams and estuaries are hastened, and there
is a general tendency to form a straight shore.?

The marshes built out in the depressions are soon covered with man-
groves, and the streams in some cases wander behind the beaches for
some distance before breaking through them to enter the sea. We thus
eventually have the coast marked by a succession of tide marshes and
lakes, with long straight beaches in front of them, and with here and
there a headland coming down to the sea.

If, however, the silts cut from the shore-line are swept away by the
currents, either along the shores or seawards, the coast soon exhibits a
continuons bluff and the sea encroaches upon the land until an equilib-

1 The question might be raised as to whether the materials cut from a conti-
nental shoulder would be thrown on shore or carried seaward by the undertow. I
do not think a fixed rule for this can be given. In some cases one thing happens,
and in others the other. In some localities the fine black silts containing marine
organisms are constantly thrown back into the estuaries, in other cases the coast is
kept clear of fine silts by the undertow.

(The estuaries of the Severn, etc. By W. J. Sollas. Quar. Journ. Geol. Soc.,
1883, XXXIX., p. 619; discussion by Mr. Whitaker, p. 625-626.)

Postscriptum.—In a late article Mr. Fenneman points out that waves of transla-
tion tend to carry the materials on the shores upon which the waves break, while
waves of oscillation move materials in the direction opposite to that in which the
waves move. (Journ. Geol., Jan.—Feb., 1902, X., p. 13-14.)

BRANNER: THE STONE REEFS OF BRAZIL. 127

rium is reached between the resistance of the shores and the sea bottom
on the one hand and the waves and currents on the other.

If evidence can be adduced from other coasts concerning whose history
we have more information, the case of the Atlantic coast of the United
States from New York to Florida may be cited. This coast is sinking?
and is characterized throughout a good part of its length by long straight
barrier beaches, sandspit harbors, and the silting up of the shallow
waters between the shore and the land barriers.

Forms on a stationary coast. — If a coast is at a standstill (not com-
pletely stable, for that is probably not true of any coast), the headlands
are attacked by waves, streams bring down silts from the land areas, and
these materials are thrown back upon the shores at favorable places,
forming spits, bars, and barrier beaches, while estuaries and embayments
are silted up and turned into dry land.

The forms produced upon an old or stationary coast are therefore dif-
ferent from those produced upon a sinking one in that there are liable to
be fewer harbors or other indentations on the older or stationary coast,
and that islands generally common on a depressed coast are liable to have
been washed away. Or as Dr. James Geikie puts it, “A gently
sinuous or profusely curved outline indicates old coasts.”? Gilbert
says that “simple contours and a cordon of sand, interspersed with high
cliff, make the mature coast.” ®

APPLICATION TO BRAZIL.

Ewidences of depression. — As a rule, evidences of depression are less
satisfactory, or rather they are less impressive, than those of elevation,
because the parts principally affected are carried down out of sight
beneath the water.

To any one acquainted with the physiographic features of the north-
east coast of Brazil, however, it is evident that those features agree in
the main with those of a stationary coast or with those produced by
depression and age rather than with those produced by a recent eleva-
tion. There are very few islands, if we omit the coral reefs ; the coast-
line is low as a whole; here and there headlands come down to the
water’s edge, and between these the flat-floored valleys are covered with

1 N.S. Shaler, Thirteenth Ann. Rept. U.S. Geol. Sury. for 1891-1892, Plate IL.,
p. 127. Washington, 1893. -

2 Earth Sculpture, p. 317.

© G. K. Gilbert. Lake Bonneville. Monograph I. U. S. Geol. Survy., p. 64.
Washington, 1890.

128 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

mangrove swamps or tide marshes. To be specific, however, we shall
mention what are regarded as more or less satisfactory evidences of this
depression.

Open bays. — In all probability those geographers who have expressed
the opinion that the Brazilian coast is one of recent depression have
based their opinions upon the peculiar forms of the bays of Rio de
Janeiro and Bahia. These bays not only have many of the peculiarities
of harbors formed by depressions, but may even be accepted as the very
types of such harbors.

Before the depression took place Bahia was a hilly, almost a moun-
tainous region. Its streams were rapid, its valleys steep-sided and
v-shaped ; its hills were on the whole even-topped, but erosion had
worked down among them until many of these were left as isolated
peaks above the lowering valleys about them. Most of the streams
flowed approximately where they now flow, but those now entering the
bay united in the bottom of a broad valley and flowed out through what
is now the mouth of the bay into the sea. All that is now known of
the date of this erosion is that it was post-Eocene.

When the great depression came, the Bahia valley sank and the waters
of the ocean backed up into it and made the bay of Bahia very much as
we now see it. The scour of the tides has kept the entrance to the bay
open, but the upper ends or indentations of the bay have been silted up
with the aid of the encroaching mangroves. The tops of some of the
hills were left sticking above the surface as islands. Some of these hills
were cut off by the waves, and others were left as islands, and are now
known as Mare, Ilha dos Frades, Madre Deus, Ilha das Fontes, ete.
Itaparica and Ilha Santo Amaro became islands at the same time.

The Bay of Rio de Janeiro has had a similar history. Its basin was
carved out by subaerial erosion when the land stood at a higher eleva-
tion. It sank and water flowed over and filled the valley leaving it a
broad but not very deep bay. Some of the original islands of the bay
had only shallow waters between them and the mainland, and these shal-
lows were eventually built up by the shore waste thrown upon them
until the islands were joined to the land. The Pao d’Assucar case cited
on page 124 is an illustration of this process.

The Bay of Santos, about 36.5 kilometres along the coast southwest of
Rio de Janeiro, is an excellent illustration of an open island-filled bay
smaller than that of Rio de Janeiro formed by a depression of the land.
This bay is now almost entirely choked up by the silts washed into it
from the surrounding mountains and thrown back into it from the coast.

BRANNER: THE STONE REEFS OF BRAZIL. 129

The accompanying plate (5), made from the beautiful topographic sheet
just issued by the Commissio Geographica e Geologica de Sao Paulo under
Prof. O. A. Derby, shows the general features of that interesting region.

The Serra do Mar, from an elevation of over one thousand metres,
here slopes abruptly beneath the flat mangrove swamps that lie along
its base in the neighborhood of Santos. These swamps, cut here and
there by winding tide streams, extend up and down the coast, but are
interrupted now and then by headlands —like that at Guaruja — that
are really mountain spurs extending down to the sea.

The hills over the plains about Santos are mostly mountaiu-tops pro-
truding from the mud and sands that have accumulated in the original
bay since the depression took place. Morro do Taipu, Ponta de Itaipu,
Morro do Xixova, and Morro Itararé were all originally the crest of a
ridge that continued past Barnabé Island in the direction of Pico Jacoa-
reguava, while Ponta Mandtba was the crest of another ridge passing
Guaruja in the same direction. The hills south of the Praia de Per-
nambuco were the crest of another of these parallel ridges.

A striking thing about the ports of Brazil is that the small ones have
all been choked up by coast débris, and only the two big ones, Bahia
and Rio de Janeiro, have been able, on account of the depths of their
mouths and the consequent scour of the tides, to keep their basins open.
But even these large ones are filling in from their upper ends, a process
greatly hastened on the coast of Brazil by the growth and encroachment
of mangrove plants.

Coast lakes. — Lakes may be formed along a coast by an elevation
bringing up closed basins — accidental forms of the sea floor,’ or they
may be caused by a depression of troughs, valleys, or shallow-mouthed
estuaries whose ends become closed in time by shore accretions, however
made, but generally the result of the destructive and constructive work
of the sea. The strong winds and currents that set against the Brazilian
coast the whole year round make the contest between land forces and
sea forces an unequal one; the sea is aggressive and always gaining.
The headlands are cut away and their remains thrown into every in-
dentation of the coast, damming in rivers and obliging them sometimes to
wander for kilometres behind huge spits before they can escape to the sea.

If, with these two methods of lake-forming in mind, we attempt to
get at the history of the Brazilian coast lakes, we find that information
regarding their surroundings is too meagre in most cases to enable us to

1 Such as are apparently meant by Capanema. Petermann’s Mittheilungen, 1874,

p. 230.
VOL. XLIV. 9

130 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY.

reach firmly established conclusions. In certain cases, however, the topog-
raphy is so constant in its general features that we feel warranted in
drawing conclusions. Certain of the lakes of the State of Alagoas, for
example, afford good examples of lakes produced by coast depression.

The northernmost of these lakes, the Lagéa do Norte, is surrounded
on three sides by rather steep-faced Tertiary hills of soft sedimentary
rocks. The slopes of these hills are of forty-five degrees and in places
even more.

I learned from Mr. H. Haynes, Superintendent of the Alagéas Rail-
way, that a well was driven at the railway shops near the foot of this

bluff in the city of Maceio to a depth of two hundred metres, — all the
way in loose materials. The inference is that the steep slope of the
Tertiary hills continues beneath the surface and that the filled-in sedi-
ments are more than two hundred metres in thickness.

Fic. 67. The deep well section at Maceio and its relation to the rocks of
the hills above the city.

Where the Alagéas railway runs along the lake shore in some places
there is barely room for the road-bed between the lake and the hills,
while at other places broad meadow-like plains or mangrove swamps lie
between the lake and the hills. At still others the line of the road
crosses flat-bottomed valleys in passing from one spur of the hills to
another. These hills — here steeper and there of gentler slope — extend
more than three fourths of the way round the lake’ from Maceio at its
northeast corner to the east of Coco Seco on the southwest — leaving
only the ancient mouth of the bay with a flat low border of sand between
it and the sea.

The lake is now very shallow, so much so that it is navigable even for
barcacas (small boats drawing a little more than a metre of water) only
along one channel on the south side.

Seen from the lighthouse or from the hills-that overlook Maceio, the
coastal belt inland is mostly one broad flat-topped table-land dropping
off abruptly on the coast. This table-land is made of sedimentary rocks
that lie in nearly horizontal beds, laid down during Tertiary times.

We can perhaps best
appreciate the process
by which these lakes
are made by returning
in our minds to the
conditions that must
have prevailed about
the end of the period
during which these
sediments were depos-
ited. The beds were
then at or below sea-
level; subsequently
they were lifted verti-
cally from beneath the
water and stream ero-
sion began to cut val-
leys in them, while
the waves of the sea
attacked their margins.
In the course of time
broad valleys were
eroded out where we
now have Lagda do
Norte, Lagéa Mangu-
aba, Jiquié, etc. After
the cutting of these
valleys there came a
downward movement
which carried the bot-
toms of all of them
below the level of the
sea, and made bays of
them, But inasmuch
as land erosion con-
tinued over the part
still out of water the
streams carried their
sediments into these
bays and began to silt
them up. The sea also,
cutting sands from the
headlands, threw them

pny

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yt

eras

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a De DANS SAAS Pesta =

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i

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a

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i
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From a photograph taken from Fernio Velho.

Lagoa do Norte near Maceio,

68.

Fia.

132 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

back into the estuaries and gradually formed bars across their’ mouths,
choking up their outlets, and thus turned them into brackish water
bodies. Their end it is easy to foretell: they will gradually become
smaller and shallower, and at no distant day will be great marshes, each
with a sluggish stream winding through it, and still later low flat varzeas.

| THE
COASTAL LAKES OF
THE STATE OF :

ALAGOAS, BRAZIL}:

_*——

After the Bs
Hydrographic aie

Scale:

eS ese miles

Fig. 69.

On the coast between Rio de Janeiro and Cape Frio are several lakes
shut in by the coast sands that have been thrown across the mouths of
valleys opening toward the sea. The country immediately north of these
lakes is a mountainous one, the land rising to elevations of from one
thousand to fifteen hundred metres in a distance of thirty or forty kilo-
metres. Between some of the lakes low headlands come down to the
beach. Lagéa Maricd, for example, has such headlands at both its

BRANNER: THE STONE REEFS OF BRAZIL. 133

eastern and western ends ; so has Lagéa Gururupira ; Lagoa de Araruama
has the peaks of Cabo Frio at one end and the hills of Ponta de Sagua-
réma at the other. These lakes thus stand on the sites of sunken coastal
valleys whose mouths have been closed by the shore waste, and whose
upper ends have been silted up by materials brought down by streams.
Sand banks or bars are liable to be built across any sharp curve in a
coast-line ; behind these bars lakes and pools are formed, and later these

n -
\ mee] pasts
tat hQerere. 6 me

ae Le
“i

ma
ts
c Katt bit

Fie. 70. Bird’s-eye view of the region about Trai¢io and the mouth of Rio
Mamanguape, showing the relation of the stone reefs to the shores.

silt up, forming marshes and eventually land. On the Brazilian coast
some of the lakes are fresh and some of them are brackish according as
the influx of fresh water is large or small.

At Traigao, State of Parahyba do Norte, the Lagéa de Sinimbi, a
fresh-water lake, is shut in by a narrow neck of sand that compels the
drainage to find an outlet to the sea through the Mamanguape River
several kilometres away. The entire seaward rim of this lake is made
of recent sands. South of Traigio this barrier is about two hundred

134 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

metres wide, and is piled with dunes, some of them as much as ten
metres high, but at and north of the village the rim is only about
forty metres wide and two or three metres high. The land side of the
lake is of Tertiary (?) sediments rising in a plateau from twenty to
thirty metres high. A section from Sao Miguel church on these hills
across the lake is given herewith.

Fig. 71. Section from the hills at S. Miguel church across Lagoa Sinimbiu.

The history of the place appears to be as follows: when the Tertiary
sediments that form the coast plain rose from beneath the sea, they
reached an elevation considerably higher than that at which they now
stand. Erosion followed, cutting narrow valleys in these beds; then
came a depression that carried beneath the sea the Jowlands near the
coast and the lower ends of some of the valleys. Marine erosion on the
newly exposed beach-lines tore down the headlands, and the sands were
heaped up by the waves as sand-bars which, in time, separated the salt
from the fresh water.

The lakes along the coast of Ceara are produced, in my opinion, in
one of two ways, either by the throwing up of beaches by wave action
like those on the sandy west coast of France,’ or else by the shifting
sands of the dunes damming back or changing the courses of rivers, as
is known in Rio Grande do Norte, Ceara, and in Sergipe.?

One of the chief reasons for believing that certain lakes have been
shut in by the constructive action of the present sea and not simply to
have found ready-made basins is that if an opening be made in the rim
separating the lake from the sea the breach is immediately closed by the
sea. The lower courses of many of the rivers stand in the same relations
to the sea as do lakes similarly located, except that the rivers are cer-
tainly more capable of keeping their mouths open than are lakes.

Rios tapados. — The city of Recife stands upon a long tongue of land
behind and around which flow the Beberibe and Capibaribe rivers.
Among the various plans for improving the port of Pernambuco one

1 Andre Delabecque. Les Lacs Francais, p. 47-49. Paris, 1898.
2 See J.C. Branner. Cretaceous and Tertiary geology of the Sergipe-Alagoas
basin of Brazil. Trans. Amer. Phil. Soc. 1889, X VL, p. 376.

BRANNER: THE STONE REEFS OF BRAZIL. 135

suggests the cutting of this neck just south of Fort Brum.? But this
neck has been cut through on more than one occasion, and the breach
has been closed by the sea in spite of the fact that the break greatly
shortens the course of the Beberibe to the sea.

In the Instituto Archeologico e Geographico of Pernambuco is an
interesting old water-color of the city said to have been made between
1822 and 1844. This picture shows a break in this peninsula between
Fort Brum and Recife. Several persons who have lived for many years
at Pernambuco have assured me of such breaks having been made from
time to time by the sea and afterwards filled up by the same agency.

On a trip down the coast from Pernambuco to Maceio, made in July,
1899, I observed several instances of sandy necks cut through by the
streams behind them and immediately afterwards repaired by the sea.

At Ihetas Point (S. lat. 8° 45/30!) .

a small stream, Rio Ilhetas, ap- °
proaches the coast at right angles,
but instead of entering the sea at
once it swings northward, unites with
another stream, and enters the ocean

a kilometre or two away, under the
protection of a wide sand-bar. At
the.time of my visit, near the end of
the rainy season, the river at an ebb-
ing tide had broken through the nar-
row neck of sand that prevented its
direct entrance to the sea, and cut a
gap as wide as the river and more
than two metres deep. But instead
et reste Keep ee Fic. 72. Breached sand neck, Rio
new mouth open, the very next in- Tibetan.

coming tide not only threw the sand

back into the opening but piled through on top of it a great cone that
the river was now compelled to cut out of its original channel. On the
whole, there was a decided loss for the stream.

Again, where Rio Una approaches the sea near Varzea (S. lat. 8° 49’),
a similar break was made by a larger stream. The opening was about
two kilometres north of the month of the river, was 2.3 metres deep, and
forty metres wide. The stream opposite the opening is one hundred
metres wide and has a strong current. With an outgoing tide during

1 M. de Barros Barreto. Projecto de doca no porto de Pernambuco. 1865.

136 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

the rainy season the river had sapped the sand-bank that separated it
from the sea, but the next incoming tide had thrown the sand back into
the opening, and had heaped into it and
into the river’s,channel an enormous delta
of new material that considerably narrowed
the channel and that the river must now re-
move. At the next high tide the sea would
be able to more than complete the repairs of
the breach.

The same phenomena were observed five
hundred metres above the mouth of Rio da
Cruz, the small stream next south of Abreu
de Una. The breach on the Rio da Cruz
was only about sixty metres wide.

With these illustrations in mind let us
turn to the case of Lagéa de Sinimbé in
the State of Parahyba do Norte. Suppose
a flood or any agency whatever should cause
the waters from Lagéa Sinimbai to cut
through the narrow sandy neck north of
—_ s oBicccieden ae the village of Traigao. . It is evident that

Rio Dan the waves would immediately, or as soon as

this extraordinary agency ceased to be ac-

tive, throw the beach sands into the breach and turn the drainage

away to the south where it can join its forces to those of the Maman-

guape River and get into the sea under the cover of the mangrove

swamps, sand-bars, and stone reefs that there protect it from the
ocean.

One of the most impressive examples of the damming in of the coast
lakes by the sea is that of the Rio Jacaresica a few kilometres north of
the city of Maceio, State of Alagéas.

That stream is shown upon the hydrographic chart as flowing into
the sea, and doubtless at one time it did so, but when I passed along
that beach in August, 1899, no such stream was flowing across it, and I
was informed by residents that for fifteen or twenty years the Jacaresica
had been a rio tapado, or stream with its mouth closed.

In this connection I am reminded that there are several small streams
along the Brazilian coast known as rios tapados. One of these is only a
few kilometres north of Olinda on the Pernambuco coast.

The following sketch was made on the coast between Rio da Cruz and

BRANNER: THE STONE REEFS OF BRAZIL. 137

Sao José, about S. lat. 8° 52’, Here the sea has encroached upon an
old mangrove swamp. The two ends of a former channel have been cut

across, but instead of these channel ends
being left open they have both been closed
by sand thrown into them by the sea, thus
enclosing two miniature lakes.

Hartt mentions such a case on the
coast of Espirito Santo: “Just north of
the Doce and near the coast is a large
lagoon called Monserras. During the dry
season this is separated from the sea by
the sand-beach, but when the rains come
it opens for itself a channel to the sea,
which channel remains open until the dry
season returns. . . . When I went to the
Doce from Sao Matheos this bar was closed,
but on my return, in the latter part of
December, it was open and dangerous to
cross.” }

The closing of all these breaches by the
sea must be accepted as meaning that the
sea along the northeast of Brazil is quite
capable of both making and maintaining
the embankments that shut the lakes in
on the seaward side.

Choked embayments. — A large number
of choked up embayments and estuaries
along the Brazilian coast might be placed
here in evidence. Only a few of them
can be mentioned.

The city of Recife itself stands on one
of these choked up bays, though rather an

Fie. 74. Sketch-map of the
former channel of Rio
Santa Cruz.

open-mouthed one. The hills of Olinda stand at the northern end of
the Pernambuco embayment, while its western boundaries are indi-
cated by the line of steep-faced hills that sweep inland past Beberibe,
Beberibe de Baixo, Casa Amarella, Monteiro Dois Irmaos, Caxangi,
Engenho Sao Joao, approaching the Sao Francisco Railway two kilo-

metres southwest of Béa Viagem station.

From this point the hills

swing inland again and only come near the railway at Ilha station, and

1 Geology and physical geography of Brazil, p. 106.

138 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

passing the city of Cabo reach the coast at Pedras Pretas some thirty
kilometres south of Olinda.

With the exception of the sandstone reefs there is not a hard rock
exposure on this entire beach from Olinda to Pedras Pretas, It is all

wt Sper
BN em 2
Ti;

~S

a

WinwCZZ
(

Ss

ZO

DAS)

Bird’s-eye view of the Pernambuco embayment.

loose sand heaped by winds and waves a little above high tide-level, and
behind the flats of sands near the coast-line are mangrove swamps, old
and new, lakes, marshes, varzeas, and sluggish streams.

BRANNER: THE STONE REEFS OF BRAZIL. 139

South of Cabo Santo Agostinho the great sandstone reef stretching
from the Barra do Suape at the old fort on the cape to Ciipe, a distance
of twelve kilometres, shuts in another old embayment into which still
drain the Suadpe, the Tatudca, the Ipojtica, and the Merepe rivers. The
hills that bound this ancient embayment start with the cape, swing
inland many miles, and reach the coast again only near Ponta do
Serramby. Within this embayment are a few isolated hills that
formerly made islands in the shallow but now silted up bay.

The Rio Parahyba, in its lower course, now flows through a silted up
bay that once extended south and west of the city of Parahyba do Norte.
Seen from the upper city, this old bay is now represented by the cane-
fields, marshes, mangues, and sluggish streams of the Parahyba valley.
The filling up has progressed so far that the sands have filled far beyond
the old mouth of the bay, and the newly made sand-flats of Cabedello
extend to the base of the hills on which Parahyba stands, and almost to
Cabo Branco itself.

The Cunhahi River in Rio Grande do Norte is the last remnant of a
bay that formerly opened between the hills of Cabo Bacapory and Bahia
Formosa on the south and the hills at the base of which the Cunhahi
now enters the sea. This was a long narrow bay that extended many
miles inland. Many similar streams along that part of the coast are now
characterized by lakes of considerable size in the process of transforma-
tion into marshes or dry land.

Depressed valleys. — A characteristic feature of the coast of Brazil
from Rio Grande do Norte to Prado, in the southern part of the State
of Bahia, is the topography about the streams where they debouch upon
the coast. Seen from the ocean, they generally present some such out-
line as that shown in the accompanying cut.

Fic. 76. Type of submerged and silted coast valley.

Such forms are quite in keeping with the theory herein maintained.
The present river valleys were cut out when the land stood at a higher
level ; when the depression took place these valleys were partly sub-
merged, and in the course of time their shallow mouths have been

140 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

choked with sands thrown up across them by the waves, while their
upper portions have been filled up with silts from the land, and with
organic matter. There isa large number of small rivers whose lower
courses have had this history. Only a few of them need be mentioned.

Rio Guaji, at the bound-
ary between the State of
Parahyba and Rio Grande
do Norte, has a broad flat
bottom filled with sand, ly-
ing between rather steep-
faced hills.

Rio Sibatima, a small
stream north of the Cun-
haht, has a similar topog-
raphy about its mouth.

The Pirangy, though al-
most closed by a high sand-
bank, has essentially the
same general topography.

In the State of Parahyba
we have similar forms at
the mouth of the Miriri,
north of the capital, and
the Grahu, south of the cap-
ital, not to mention the
larger streams. In _ the
State of Pernambuco simi-
lar forms are common,

—————

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Sketch of the topography of a part of Rio Jaguaripe, state of Bahia.

OO eae

E
~ though often modified by
‘;_ having the flat coast sands
& built out beyond the steeper

bluffs, thus merging the flat
river valleys into the flat
sandy coast plains.

If good maps of them were available, some of the rivers about Behia,
the Jaguaripe, for instance, would illustrate this matter beautifully. The

Jaguaripe, however, is very poorly shown upon the hydrographic charts.
The sketch-map (Fig. 77), mostly constructed on the spot, will give, not
the exact form, but rather an idea of the generalized features of a portion
of the region.

BRANNER: THE STONE REEFS OF BRAZIL. 141

The shores along the lower part of the river are all low, and mostly
covered with mangrove swamps; the highlands begin at the town of
Jaguaripe on the south side; on the north side they begin a couple or
three kilometres further upstream. These hills are some thirty-five
metres high. They have steep slopes, some of them being nearly per-
pendicular, that plunge without a break beneath the mangrove flats.
When one can get a broad view over these mangrove flats, he sees them
ending like a water-line against the foot of the hills. The landward
margins of the mangrove swamps now follow for a distance parallel with

Fic. 78. Outline sketch of the topography at the mouth of Rio Santa Cruz.

the stream, and now turn Square away from it, run inland for a kilo-
metre or two, and then curve sharply back upon themselves, thus pro-
ducing a regular dendritic form. In places these swamps are built out
in front of hills, in others the river cuts the foot of the hills, and the
Swamps fill the valleys between them like the membrane between the
fingers of the human hand.

The present Jaguaripe river, in any case, is a very crooked one, now
washing the rock bases of bluffs, and now winding through the midst of
great mangrove swamps.

These are the features of a region having originally a rather sharp
drainage and narrow, steep-sided valleys, but now let down until the
sea has invaded the lower
ends of the valleys, and these
valleys are more or less silted
up and taken possession of by
mangrove swamps.

The mouth of the Santa
Cruz river, in the State of
Bahia, seen from the north
end of the Alagadas reef, has the outlines shown in the accompanying
sketch.

The bluffs at the town of Santa Cruz are so steep on the northwest

Fig. 79. Sketch of the bluff at Santa Cruz.

142 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

face that they are nearly perpendicular. The sketch below was made
from a point further south, and looking due west toward the town.

At Porto Seguro the flat-bottomed nature of the valley is more striking
than at Santa Cruz. The hills are the same Tertiary sediments, with
valleys cut down in them. At the north edge of the upper city one of
these valleys appears not to have been quite deep enough to let the sea
into it, but the valley of the Rio Cachoeira being larger, there was here
formerly a long narrow estuary that has become silted up and turned
into dry land.

The view from the top of the south edge of the plateau near the upper
city at Porto Seguro is an impressive one. The slope of the bluffs is
close to 45°, the valley is broad, almost perfectly flat, and less than a
metre above high tide-level. The sketch on p. 98 will give an idea of
the more prominent features of the region.

Some interesting examples are visible on the cliffs exposed north of
Prado, State of Bahia. The following sketch shows the barreiras, or red
clay bluffs, just south of Comoxatiba in the vicinity of the monazite sand
deposits.

Fic. 80, Sketch of the truncated hills north of Prado, as seen from the ocean.

The striking feature of this view is that some of the little valleys stand
high above the sea-level, while others appear to have sunk quite below it.

The history appears to have been an elevation after the deposition of
the sediments ; during this elevation the drainage cut the valleys. Then
followed a depression, and the lower valleys went beneath the sea, while
the higher portions were not affected. Marine erosion has truncated
and exposed many of these valleys in the bluffs.

That the estuary valleys are sometimes still partly open or not
quite filled up is due to the scouring action of the tides. For estuaries
with streams entering their upper ends have to discharge at ebb tide
more water than they receive during flood tide, hence the outflowing
current must be more rapid than the inflowing one. They can only fill
up from the upper or landward ends, and by the combined action of
mangroves and of silts brought down by the drainage. The seashore
silts cannot reach so far up streams.

Should it be suggested that these flat lands might be produced by an

BRANNER: THE STONE REEFS OF BRAZIL. 143

elevation of the sea-bottom, I would reply that an elevation of the coast
would give the streams greater fall and velocity, and that, instead of silt-
ing up as they are now doing, they would at once begin to erode their
channels.

The case of Rio Sao Francisco. — The Rio Sao Francisco appears to be
an exception to the rule that governs the other streams of this part of
the coast of Brazil. But the Sao Francisco is a large stream — the
largest one entering the Atlantic between the Amazonas and the Rio de
la Plata. It has already been pointed out that there is a never-ending
conflict between the land and the sea forces. Along this coast there is a
tendency on one hand for the silts to be thrown back into the mouths of
the streams, and on the other hand for them to be forced out to sea by
the waters of the streams. What the result is depends upon the com-
parative powers of these two agencies. If the sea is the more powerful
agent the mouth of the river is closed and its waters are compelled to
dodge behind a reef, island, bar, or bend in the coast-line in order to es-
cape to the sea. Sometimes they must wander for kilometres in search
of this protected outlet. Sometimes it happens that the energy of the
stream is temporarily increased by floods to such an extent that it is able
to break across these wave-constructed barriers and enter the ocean boldly.
But when the floods subside the waves resume their control, the new
passage is closed, and the stream returns to its former channel.

In the case of the Rio Sao Francisco the volume of water is at all
times so large that it is able to flow squarely into the ocean and to keep
its immediate mouth clear by throwing out bars well in front of it.

A slight elevation or depression is not likely to produce changes about
the mouth of such a stream as the Rio Sao Francisco that would be as
readily recognized as they would be about a smaller stream. The lower
valley has already been silted up far in advance of the highlands, and as
one enters the river from the ocean he sees only great stretches of low,
flat delta lands about its mouth. The high ground is reached several
kilometres upstream —at Villa Nova on the south side, and near
Penedg on the north. The valley above these points is broad and
flat, but it ends abruptly against the rather steep hills on either side.

Iam unable to say whether this topography of the lower river is that
of a drowned river valley, or is produced simply by the ordinary floods
that annually spread over a large part of it.

Higher up stream — at Piranhas—the river flows over a rock bottom,
but this is one hundred and eighty kilometres from the present river
mouth,

144 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

Downstream the form of the channel is that of a depressed v-shaped
valley, and this finally merges into the broad, open, but flat-bottomed
valley, with the high banks far apart.

The Amazon is also too powerful a stream to be shut up by its own
silts.

Evidence of the islands. — The process by which islands are formed
by depression consists in the lowering of the general land surface until
the sea passes up some of the valleys and gets behind or landward of
some of the highest points. The island of Itamaraca, for instance, before
it became an island, had one stream flowing past its northern end —the
Tijucapopo (or Catuama)— and one flowing past its south end — the
Tguassi — and the canal that now separates it from the mainland was a
valley through which small streams drained both north and south.
When the depression of the coast took place the water backed up into
the lower parts of these streams and into the valley behind it, thus
entirely cutting it off from the mainland and leaving it an island.

The island of Itaparica and the other islands in the Bay of Bahia are
also the higher portions of irregular land surfaces let down by a depres-
sion till the water of the sea flowed round them. Itaparica channel
is a drowned valley that formerly drained northward into what is now
the Bahia de Todos os Santos, but which was formerly a valley. The
same thing is true of the islands of Tinharé and Boipéba on the coast
south of Bahia.

If we wish to test the theory of these islands having been made as
here suggested we have but to imagine the effect of an elevation upon
them. The deepest water recorded in the channel west of Itamaraca is
less than three fathoms. If the land were elevated more than three
fathoms evidently this water would run out and we should have a small
stream flowing where tide water now enters. Many islands on a coast
are usually regarded as evidence of a late depression of that coast. It
might be supposed, then, that inasmuch as the Brazilian coast has re-
markably few islands, this absence of them might be taken as evidence
against a late depression. The islands that do exist, however, bear out
the theory of a depression, while the absence of a large number of small
outstanding islands bears out the idea that the depression took place
long enough ago to allow the sea to obliterate them, and in some in-
stances to throw their remains on the shores of the mainland. These
same silts also helped join to the mainland some of the in-shore islands.

Off-shore clays. — The borings made by Sir John Hawkshaw on and be-
hind the reef at Pernambuco in 1874 penetrated to a maximum depth of

\

seventeen metres. The rock of the
reef was found to have beneath it
beds of sands, shells, marls, and clays.
Some of the clay beds are more than
two metres thick. These clays afford
additional evidence of the outbuild-
ing by silts of the formerly indented
coast-line. Clays being light, sedi-
ments can be deposited only far
enough offshore to be ont of the
reach of the strong in-shore waves.
The beach at the time of the depo-
sition of the clays must therefore
have been further inland, and the
clay beds were buried by later sedi-
ments swept seaward as the beach
was built outwards.

Evidence of buried rock-channels.
— Somewhat in the same line is the
evidence of a buried channel discov-
ered by Mr. Samuel H. Agnew, at
Parahyba do Norte, on the line of
the Conde d@’Eu railway. In 1887-8
this railway was prolonged from the
city of Parahyba to Cabedello, at
the mouth of the Parahyba river,
and Mr. Agnew had charge of the
construction. Where the line crosses
the upper ends of three mangrove
swamps immediately northeast of
the city station, great difficulty
was experienced in carrying the
road-bed over the soft mud, owing
to its yielding under pressure and
allowing the railway to sink. In-
asmuch as the largest of these
mangues has rock cuts on both
sides of it, it was assumed that the
mangues had rock bottoms, and
accordingly soundings were made

1 Melhoramento dos portos do Brazil.
Relatorios de Sir John Hawkshaw. An-
nexos. Rio de Janeiro, 1875.

17 Kicomerers

44:0, CUZ
aus Lin CE te

.

===aaseee
I 1a

Tat
=

——

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==

sae

a=

=I

a =:

a

“ai ie
ad &

T

=a 6 ta

L

Es

on THE Conde ov° Ev Raihway SHOWING THE DEPTH OF THE MUO FILLING SUBMERGED TRENCHES IN LIMESTONE

Secrion

nese CRETACEOUS LIMESTONE

Mubd OF MANGROVE SWAMPS

200 METERS

? METERS
oo

a4

fas

°

VERTICAL
HORIZONTAL

SCALE {

81.

Fic.

146 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY.

along the line of the road to ascertain the depth of the mud down to
the rock floor. These soundings were taken with steel rods, and the
mud was so soft that two or three of the rods were lost by slipping from
the hands of the men and disappearing very much as if they had fallen
into water. The original profile of the railway, together with rock cuts
and soundings across these mangues, was kindly furnished me by Mr.
Agnew. They are copied here, beginning with the upper left hand at
kilometre 16 from Cabedello. :

It will be seen that the mangrove swamp here fills gullies that were
eut originally in the hard limestone. The outlines show them to have
the form common to stream channels, and as such channels could only
be cut when the place was above water level, we are obliged to assume
that the land at this place formerly stood enough higher to allow water
to flow freely down these gullies. The greatest depth of the mud along
the profiles is 11.70 metres, which, added to the depth of water in the
mangue above the mud, gives a total depth of at least 12 metres. In
order to restore the conditions under which this deepest channel was
cut, we must assume an elevation of the land of at least twelve metres.
But inasmuch as the railway runs across only the upper or shallower
ends of these swamps near the Parahyba hills, it is fair to assume that
the main channel of the Parahyba is considerably deeper. Their prox-
imity to the hills likewise precludes the possibility of the channels
having been cut by tidal scour.

Additional views of depression. — Shaler expresses the opinion, prob-
ably based upon such maps of South America as are available, that the
region about the mouth of the Amazon “has recently been lowered to a
considerable depth.” ?

Dr. James Geikie says: ‘The general trend of the coast-line of South
America . . . from Pernambuco to the mouth of the river Plate, coin-
cides with the direction of the continental plateau, and may be said,
therefore, to have been determined by crustal movements.” He thinks
the region about Rio has been depressed.

Although Hartt expressed a belief in a recent elevation of the coast,
he also refers to evidence of a recent depression. This evidence consists
of recent cemented sands covering “ drift”? clays ‘down nearly to low
tide. This fact seems to prove satisfactorily that formerly the land
stood at a higher level even than now.” °

1 N.S. Shaler. Evidences as to change of sea-level. Bull. Geol. Soc. Amer.,
1895, VL., p. 162.

2 James Geikie. Earth sculpture. New York, 1899, p. 332.

3 Geology and physical geography of Brazil, p. 572.

— = 5

BRANNER: THE STONE REEFS OF BRAZIL. 147

Inasmuch as the “ drift clays” mentioned by Hartt were regarded by
him as of glacial origin, he seems to have thought it necessarily a land
deposit, and that the coast was submerged since the glacial epoch.

It has been shown elsewhere? that there is no satisfactory evidence
of glaciation in Brazil.

The ‘ drift” Hartt mentions is probably a part of the water-worn
material covering the region lifted from beneath the sea at the close of
the Tertiary. It indicates a depression since that emergence.

Hartt also recognized the evidence of the Alagdas lakes, for he says
(p. 422): “These lakes of Alagéas, as well as Juparana, are very deep,
and their basins must have been excavated at a time when the land
stcod at a greater height than at present.”

Darwin notes the existence of fresh-water Tertiary beds at the head
of the Bay of Bahia “now washed by the sea and encrusted with Balini ;
this appears to indicate a small amount of subsidence subsequent to its
deposition.” I suppose the idea is that the fresh-water deposits were
laid down above tide-level. This may or may not have been the case.
The bottoms of the great fresh-water lakes of North America are far
below sea-level.

On the island of Fernando de Noronha, two hundred miles northeast
of Cape St. Roque, wind-bedded sandstone of recent geologic origin
extends beneath the water at high tide.

There can be no doubt about the wind-bedding of these rocks, for in
some places the false-bedding dips strongly toward the hills against
which they are deposited.2 The wind-bedding could only be produced
above water. This shows that there has been a depression’ of the land
since the sands were deposited.

Elisée Reclus in speaking of the encroachment of the sea about the
mouth of the Amazon says that it seems to be due to a general de-
pression of the coast. As evidence of the recent depression of the
region about the mouth of the Amazon, Coudreau mentions a large
number of enormous stumps in the bed of the little Mapa river on the
coast (2° N. lat.).*

1 J.C. Branner. Thesupposed glaciation of Brazil. Journ. Geol., 1893, I., p. 753-772.

2 J.C. Branner. Geology of Fernando de Noronha. Amer. Journ. Sci., 1889,
XXXVIL, p. 160-161.

J.C. Branner. The eolian sandstones of Fernando de Noronha. Amer. Journ.
Sci., 1890, XXX., p. 247-257.

8 Flisée Reclus. Nouvelle géographie universelle. Tome XIX. Amérique du
Sud, p. 146. Paris, 1894.

4 Henri A. Coudreau. Voyage & travers les Guyanes et l’Amazonie, p.
10-11. Paris, 1887.

148 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

EVIDENCES OF ELEVATION.

While the evidences of depression stand out boldly in the topog-
raphy and geography of the Brazilian coast, —so much so that by an
inspection of the maps alone geographers who have never visited the
region have been able to interpret them, — yet there are here and there
evidences of a late elevation.

This elevation, however, was a feeble one as compared with the
depression. Although the uplift was the later movement of the two,
the marks of it are not so abundant or so bold as are those of the great
depression. The evidence of the elevation is here brought together.

Reference should again be made to what was considered by Capanema
and Liais as evidence of an uplift of the Brazilian coast. These matters
have already been disposed of on pp. 118 to 125. Unfortunately, out of
seven classes of facts brought forward by these writers the only one that
has any claim to attention in support of the theory of elevation is one
given by Capanema as islands joined to the mainland, and possibly that
of coastal lakes. But even in these cases islands joined to the land
and coast lakes cannot be accepted in support of the theory of elevation
unless they have the characteristics of islands and lakes produced by
elevation. Islands are joined to the land after depressions as well as
by elevations, and coast lakes are formed along depressed coasts quite as
readily as along elevated ones. In order to know how islands have
been joined to the mainland, and how lakes have been formed, it is
necessary to know something of the local geology and geography. In
the absence of such knowledge the islands and lakes, excepting the
cases already cited, must be left out of the discussion.

The “evidence of elevation collected by the author consists of:
1. Elevated sea beaches; 2. Elevated sea-urchin burrows; 3. Death
and decay of the coral reefs. These will be treated in this order.

1. Elevated beaches, State of Alagéas. — Tatuaminha is a small village
on the south side of a river of the same name that enters the Atlantic in
S. lat. 9° 16’, State of Alagéas. South of the village a flat bit of
country from one to two kilometres wide lies between the Tertiary hills
inland and the sea-coast. Mangrove swamps cut into this flat land at
several places, but most of it is covered with very calcareous sand con-
taining vast quantities of marine molluscan shells, such as are only found
living on the open coast. No note was made of the elevation of this
plain above tide-level, but my recollection of it is that it is from one to
three metres.

BRANNER: THE STONE REEFS OF BRAZIL. 149

North of Rio Camaragibe (S. lat. 9° 19’) in the State of Alagéas, at
a place known as Marceneiro, the following section is exposed on the
beach.

Coral recf ey

Fic. 82. Section at Marceneiro.

This calcareous rock rises about 2.3 to 2.6 metres above low water,
while the total height of the bank amounts to 3.2 metres above low
tide.

Elevated beaches, State of Bahia. —In 1879 Richard Rathbun, for-
merly member of the Commissdo Geologica do Brazil, now of the Smith-
sonian Institution, published an article on the stone reefs, in which he
gives a brief description of an elevated beach at Porto Santo, on the
island of Itaparica, bay of Bahia.t| This description is so important that
it is given at some length: “At Porto Santo, there is a curious
example of consolidated beach structure, the only instance of the ele-
vation of such material of which we are aware. At this place we find
a cliff back of the beach, having a length of about 1,100 feet, and a
greatest height of about thirteen feet, and composed almost entirely of
sand and gravel, cemented by lime into a sandstone. The lower part
of the cliff is very hard in texture, and contains numerous fragments of
corals and shells, the latter being frequently found entire. Many of
the species of both exist in abundance throughout the bay. The upper
part of the cliff is of almost ‘pure sand, and has been so incompletely
hardened as to crumble readily between the fingers. The amount of
calcareous material in the lower portion is very great, and it is said to
yield a good quality of lime on burning.

“ Whether this cliff belongs to the same class of structures as the reefs
or not, it is, at least, composed of the same materials, and must have
been formed in about the same way. Its present elevated position —

1 American Naturalist, June, 1879, XIII. 347-358. A somewhat longer article
on this same deposit was published by Mr. Rathbun, entitled A praia consolidada e
sublivada e os sambaquis de Porto Santo. Archivos do Museu Nacional do Rio de
Janeiro, 1878, III., p. 172-4.

150 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

for high water reaches only slightly above its base —indicates that the
shore has been raised at this point to a height nearly equaling that of
the cliff. What gives an increased interest to this locality is the pres-
ence of a low kitchen-midden, only two or three feet thick, which over-
lies the entire cliff. It is composed of a dark-colored, sandy earth,
packed full of the shells of the edible mollusks of the bay, with a few
scattered bones, and occasionally a human skeleton.”

When I was at Bahia in August, 1899, Mr. Joseph Mawson directed
my attention to important evidence of elevation north of Sao Thomé on
the bay of Bahia, and on the trip to and from that place I was able to
collect many other bits of evidence pointing to an elevation of the coast.?

The accompanying sketch-map of the region, made on the spot, will
serve, in the absence of a better one, to show the topographic relations of
the points mentioned. It should be remembered, though, that both the
orientation and the distances on this map are only approximately correct.

With the exception of the late beds with which we are especially con-
cerned, the rocks of the region are all folded, faulted, and sometimes
decomposed Tertiary sediments.

At the Ponta d’Areia, a point marked A on the northwest corner of the
map, there is a flat bit of ground, not more than four acres in area.
Half of this flat ground has a sloping sandy beach, and the remainder,
in the northeast corner, has a low natural rock wall about 100 to 150
metres long for a water front. This rock lies in horizontal beds, and is
made up of shells, corals, and comminuted calcareous matter of various
degrees of hardness. The total thickness of the beds could not be seen
at the time the place was visited, on account of the tides, but they ex-
tend from below high water to about one and a half to two metres above
the highest spring tides. The uppermost metre of this is soft sand
merging into hard rock below. The surface itself is very black soil to a
depth of from fifteen to twenty centimetres, and I suspect it of having a
human origin. The material of the lowest part of the beds is of very
much ground-up shells and corals.

It is possible that the shells on this point rise to a height of three
metres above tide, but those seen on the highest grounds all belong to
species that are used for food even to this day, and it is doubtful whether
they ought to be included with the elevated beds.

At the point marked B on the map marine shells are strung along

1 Tam also under obligations to Mr. Richard Tiplady, Superintendent of the

Estrada de Ferro da Bahia ao Sao Francisco, and to Mr. Thomas Mawson, of the
same road, for facilitating in every possible way my visit to this interesting region.

BRANNER: THE STONE REEFS OF BRAZIL.

- 4. Ponta d' A reia

4

Uff --
Mf
Bel) ETCH-Map

E
oF THE
z oo °
GEE Tegion abo

152, BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

through a low neck of land at an elevation of 1.2 metres above the
highest tides. Between Ponta d’Areia and this place there are many
patches of shells along the shores, but they are usually so scattered as to
lead one to suspect them of having been left there by human agencies.

At the point marked C on the west side of the ridge a bed of shells ex-
tends along the coast at an elevation of from 1.2 to 1.5 metres above tide.

At D on the map the encroachment of the sea has exposed another bit
of the elevated beach.

The materials of the old beach are here shells and corals and water-
worn pebbles of Tertiary rocks resting upon the upturned and eroded
edges of Cretaceous shales and sand-
stones. Clays from the hills above
cover the deposit. The top of the
shell bed at this point is one metre
above the highest tides.

The valley north of Sao Thomé is

nearly a flat-bottomed one, having a
maximum elevation of about 2.1 me-

Fie. 84. Section of the beach north ‘ :
of Sao Thomé. tres above the highest tides. At the
points E a road crosses this valley and
descends a gentle slope to cross a small stream. The road on these
slopes cuts into a soft rock made of shells like those on the present
beach. All over the higher parts of this valley, where burrowing ani-
mals have made holes in the soil, fragments of shells have been brought

to the surface.

Fie. 85. Section in a gully south of Sao Thome.

Yellow calcareous soil with shell fragments. . . . ace ae es
Light gray calcareous soil made of shell and coral facia oa 13’
Dark chocolate brown sand with shell fragments. Color shades off

into the brownish gray beds below . . . eB ie ce

Light gray calcareous sand with many loose hetiet «8 a eee

BRANNER: THE STONE REEFS OF BRAZIL. 153

In the south end of the village of Sao Thomé and just south of the
hill on which the church stands (F on the map) a gully has been washed
out in an old road that comes down at right angles to the beach. In
this gully the section as shown in Figure 45 is exposed.

Twenty metres back from the beach the tops of these beds are about
2.1 metres above the highest tides.

All over the two mangrove swamps shown on the map the crabs have
brought up from their burrows fragments of beach forms of mollusks —
shells of species that do not live in mangrove swamps.

Before leaving Sao Thomé it is worthy of note that the shells occur
on the beach in front of the village in an almost incredible abundance.
There is at this village a considerable industry in the manufacture of
lime, all of which is made of the shells raked up on the beach.

Just north of Olaria station on the Bahia railway, and in the outskirts
of that village (H on map), is a small stream called the Tubarao.
Where this stream enters the bay, and on its north bank, there are
hardened beds of shells. They reach an elevation of a little more than
one metre above the highest tides.

Some 300 or 400 metres south of Olaria station the Bahia railway
crosses a small bridge. About fifty metres east of the track at this
bridge the shell beds are a little more than one metre above high-tide
level.

Periperi on the Bahia railway stands in a semicircular, flat-bottomed
valley very like that at Sio Thomé, and the sands of its floor contain an
abundance of marine shells. Ido not know the elevation of this valley
floor, but it is low — not exceeding three or four metres.

Marine terrace at Ilheos, Bahia. — The evidence at Ilheos consists of
terraces. One of these—the Opaba terrace— is about a kilometre
north of Ilheos, and 300 metres back from the present beach. It lies
across the mouth of a small steep-sided valley of which a sketch-map is
given here (Fig. 86).

The rocks of the hills on both sides of this valley are crystalline —
gneisses cut by dikes of diabase,1 and decayed to red clays at the sur-
face. Above the terrace is a marsh, and below it a shallow fresh-water
lake. The terrace itself is about 120 metres wide at the base, from 150
to 160 metres long, and 7.31 metres high. It has a steep front or down-
stream face— 40° and more— while the upper face slopes back very
gradually to the marsh. The material is all loose, light-brown, coarse

1 One of these eruptives was kindly examined by Mr. H. W. Turner, late member
of the U. S. Geological Survey, and found to be a good typical diabase composed
of basic feldspar, monoclinic pyroxene, and magnetite.

Slieteh Mer

| LHEOs
S tate of Bahia

N

’
Boa Visla ‘

y,
The OQhaba Cerrace }

Fic. 86.

BRANNER: THE STONE REEFS OF BRAZIL. 155

quartz sand; some of the sand grains are as big as peas. No shells
were found over the surface save recent land shells.

A hundred and fifty metres north of the terrace a small fragment of
soft sandstone, in texture very like the sand of the terrace, lies against
the schists of the hill at about the same elevation as the terrace. The
photograph of the terrace was made from this point (Plate 69).

This Opaba terrace is the only one examined at Ilheos, but there are
other terraces in the vicinity at about the same elevation as this one,
and probably of the same age. These are mentioned here rather for the
purpose of putting them on record for future observers than as evidence
that can be trusted without further examination.

About three kilometres north of Ilheos, on the beach at a place called
Vellosa, is a terrace apparently about the same height as the Opaba ter-
race. The Vellosa terrace is a noticeable feature when seen from the
sea as one approaches Ilheos from the north. It appears to be about
half a kilometre long, is perfectly flat as seen from the front, and has
the drainage from behind it coming round its south end. It stands
across the mouth of an embayment and is covered with coco palms.

A photograph was taken of this terrace from one of the rocky points a
kilometre to the south (see Plate 70).

Southwest of the town of Ilheos, on the opposite side of the river, is
a hill shown on Mouchez’ chart of this port. At the extreme northern
end of the hill there seems to be a remnant of a terrace, while half a
kilometre further south on the side of the same hill traces of the same
terrace are visible. I do not doubt but that if they were uncovered
these terraces might be traced a long way up and down the coast, but
the jungle-covered, uncultivated condition of most of the region makes it
impossible to get more than a mere glimpse of them here and there.

Lagoa de Itahype.—Spix and Martius mention what appear to be
elevated beaches in the vicinity of Ilheos.*

“ Banks of sea-mussels appear not only on the mainland, but to greater
extent on the sea-coast. The shells belong to none but living marine
mollusks, as Ostrea edulis, species of Tellina and Fasciolaria. They are
usually only slightly altered. Often the cement or sea-sand so predom-
inates that this still constantly growing formation can be used as build-
ing material ; if, however, lime predominates, lime is burned from it.
. . » The presence of these mussel banks, as well as the coral distant so
many miles from the coast, and the entire formation of the land on this

1-J. B. Spix u. C. F. P. von Martius, Reise in Brasilien. Vol. Il, note on
p. 710. Miinchen, 1828.

156 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

large plain, seem to signify that the sea has retreated here more and
more, and the products of its waters gradually surrendered to the firm
land.”

At Ponta @’Areia, Bahia. — Ponta d’Areia, the terminus of the Bahia
e Minas Railway, stands on a sandy flat that reaches from the sea at the
Barra de Carayellas up the river to the old city of Caravellas—a dis-
tance of five kilometres. Following the line of the railway this same
sandy plain continues to kilometre ten. This much of it I have
examined, but the configuration of the country suggests that this
sandy plain extends far up and down the coast — possibly as far as
Prado.

At Ponta d’Areia the plain has a maximum elevation of only 2.29
metres above high tide; near Barra de Caravellas it is from 2.5 to 3
metres, and at the city of Caravellas it is: from 2 to 2.05 metres above
tide. The profile of the railway is not available, otherwise the elevation
of the landward margin of this plain might be given.

This plain is not hummocky like a sand plain heaped up by winds
upon a growing beach, but is characterized by long gentle slopes that
are imperceptible to the eye, and by sudden changes of level like the
materials of a sand bar.

The upper part of these sands is generally of a grayish color darkened
with organic matter, while at a depth of 0.2 to 0.4 metres they are of a
yellow, almost an orange, color.

I have spoken of these beds as sands: on top they generally are sands,
but at a depth of a metre or so they are often sandy clays, so much so
that they are used for making pottery, bricks, and tiles. I have not
seen any false bedding in this formation.

Everywhere over the plain these sands contain an abundance of ma-
rine shells both entire and broken. They are brought to the surface by
ants and other burrowing animals, and are found in the shallow railway
cuts, in post-holes, and in wells.

At one place between Ponta d’Areia and Caravellas in this formation
I found also a piece of coral (Heliastrea aperta) as large as one’s fist.
I am not, however, without doubt about trusting this coral fragment. It
was found within 300 metres of Pitonga, a little village of three or four
cabins, and may have been dropped here by man. It is of a species used
for making lime.

At another place half-way between Ponta d’Areia and Barra de Cara-
vellas I found in the debris thrown from a shallow pit dug in search of
water one small specimen of coral (Astrangia solitaria). This specimen

. » . 8 =] , ?
toluvo}s Surssud v wow uayey yduasojoyd u WOLT “BOP! A YU OUT] 19JUM JUdlOUY “LQ ‘Org

GAVNAYy

— SOO SSS SS

2

a ; ~- SSS . = el saan % = SV SE Se SN

—_S s-_—__ - = arn as = =

158 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

was found under circumstances that place it quite beyond any doubt
about its belonging where it was found.

The shells have the general aspect of the shells of the present coast,
but I am disposed to think this an altogether too off-hand way of deal-
ing with them. Iam not at all sure that a careful study would not find
a considerable difference between the fossil fauna of the sand plain and
the existing off-shore fauna.

Shells may be left over a plain by the seaward extension of the shores,
or by the elevation of the sea-bottom. Inasmuch as this plain stands
from one to three metres above the highest tides, and as it is not wind-
bedded but is made up of horizontally bedded clays and sands filled with
recent marine shells, we must admit a recent elevation of at least three
metres to account for it.

At Victoria, Espirito Santo. — Hartt long ago spoke of the evidence
of elevation on the island of Marica, off the coast between Rio de Janeiro
and Cape Frio,’ at Sant’ Anna, and at Victoria, Espirito Santo. In
1899 I visited Victoria again and examined some of the evidence he
found there. This evidence consists of a horizontal line of open-mouthed
pits or depressions only a few centimetres deep but yet perfectly well
defined, and about one metre above the highest tide-level. This line is
most clearly shown on the big exfoliated peak formerly called the Pao
d’Assucar, but now generally known as the Penedo. The same sort of
a line shows at several other places in the vicinity, notably on a big
block about four hundred metres further down the river, but always at
the same level. Hartt thought this line “evidently worn by wave action
within comparatively recent times.” I am not sure what made the line,
but Iam confident that it is due to a change of water-level. The pits
are not such as are made by sea-urchins, and I found nowhere on these
rock-faces or elsewhere similar lines worn by waves. The only explana-
tion that seems ‘to be satisfactory is that they have been formed since
the elevation of the coast by the weathering along a line of partial
decomposition brought about by the effect on the rock of organisms that
once grew along that line.

I have examined the line of organic growth near mean tide and low
tide levels at many places along the Brazilian coast, and I am disposed
to think that the line of pits on the Victoria rock correspond with the
low tide line of seaweeds, barnacles, and Serpulae — the line where these
things seem best to thrive. There is no proof of this, however. It is

1 Geology and physical geography, p. 36, 42, 71-72.

Vi pA et ty

BRANNER: THE STONE REEFS OF BRAZIL. 159

simply an inference based upon the supposition that these organisms
would affect the rock along the line where they grow.

2. Elevated sea-urchin burrows. — The boring sea-urchins of this coast
(Echinometra subangularis) can live in places where at low tide the
waves break over them occasionally, or they can live in tide-pools. But
so far as I can learn they do not live in places where they are completely
uncovered at low tide.

A few kilometres north of Cabo Santo Agostinho, at a point of land
known as Pedras Pretas are many exposures of a massive black trachyte
upon the sea beach and rising in the hills above. There are three or
more places where these trachyte masses in place are bored by sea-urchins.
These rocks, and one other and larger exposure, are in place, while a
third one may possibly be a loose block. The parts bored with these
holes are between high and low tide levels. As will be seen from the illus-
tration the exposures of these bored faces are such that it does not seem
possible that sea-urchins could live in them if uncovered even at low tide.

Of the several exposures of such borings at this Cape not one is found
beyond the reach of high tide. To put these holes all below low tide
would require a depression of two metres.

It should be added that no such holes were found in the granites
exposed at Pedra do Porto and Pedra do Conde in the southern part of
the State of Pernambuco a short way north of Rio Una, but on Cabo
Santo Agostinho on the south side of the Cape and west of the sand
reef there are a few holes in the granites between tide-levels that look
as if they might have been made or partly made by sea-urchins.

3. The death and decay of the coral reefs. —The decay and erosion of
the upper surface of the stone reefs I have not seen mentioned as evidence
of elevation. The illustration given herewith shows a characteristic fan-
tastic form common upon the stone reefs of the coast. These forms have
the bedding of the original sand layers distinctly preserved and there
can be no question about their being the remnants of upper beds that
have been removed by erosion. This erosion, however, may have been
produced either by the ordinary processes of weathering and removal by
the waves, or it may have been the work of the surf. The form here
represented is still quite within the reach of the surf at high tide. These
forms cannot therefore be accepted as evidence of elevation. I do not,
however, feel so confident in regard to the meaning of the decay of the
upper portion of the coral reefs of the coast. I know of no reason why
the stone reefs may not have been consolidated at any elevation at which
they are now found. But in the case of the coral reefs the rock can be

160 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

formed only where the living polyps and other reef builders are always
covered by water. This does not necessitate their always being below
low tide level, for corals grow constantly in tide-pools, and Serpulae often
build up rims enclosing basius whose surfaces are left several feet above
low tide. In such basins corals may flourish above sea-level. But while
these cases are not at all uncommon, the area covered by them, when con-
sidered in relation to the whole area of the coral reefs of which they form
part, is very small indeed.

Fic. 88. High Rock, Maceio coral reef. From a photograph by F. Ambler.

Along the entire coast from Parahyba do Norte to Parcel das Paredes,
the Abrolhos, and Coréa Vermelha, the coral reefs not only rise above
low tide water over enormous areas, but the upper surfaces of all these
exposed reefs are dead, excepting in so far as they are made of such
things as grow in tide-pools. In the north the coral reefs are universally
bored by mollusks, sea-urchins, etc., and for the most part have an
etched appearance.

In the State of Alagdas, three kilometres south of Sao Miguel dos
Milagres and north of the Rio Camaragibe, there are exposures, at low
tide, of coral reefs upon the sandy shore. At the mouth of a small
stream the reef has been covered by sand, and later it has been again

~~ a ee,

BRANNER: THE STONE REEFS OF BRAZIL. 161

uncovered by the shifting of the currents. The coral reef surfaces are
usually so blackened with corallines and other growths that the struc-
ture cannot be seen, but at this place it is shown perfectly. Heads of
Porites and other corals are cut through and partly eaten away either
chemically or mechanically. At low tide these reefs- are exposed for
half a kilometre out seaward. Nearly one kilometre south of the beach
exposure just mentioned is another place where the beach sands overlie
a dead coral reef. The photograph given herewith was taken at the
last-named place. It shows not only the in-shore reef but two other
coral reefs further out: the further of these is nearly one kilometre from
the shore.

LEU

Er

ire Win ~ Es < ~ Bate
ti; Diener ques ee SH) es a
: Jo Acionene sae : pein Gai: it <a ler
Fic. 89. High Rock, Maceio coral reef. From a photograph by F. Ambler.

In this connection mention should be made of a mass of coral rock on
the reef at Maceio. The Maceio reef is of coral, is three kilometres or
more in length, and varies in width from a few paces at certain points
to nearly a kilometre at its northern end, where it joins the sandy beach.
At one point east of Jaragua a solitary mass of coral rock rises three
metres above the general level of the coral reefs. There is no other
such rock on the Maceio reefs. It was formerly supposed that this was
the remnant of an old reef that had been cut away by the waves. The
accompanying illustration made from a photograph kindly obtained for
me by Mr. F. Ambler of the Alagdas Railway Company at Maceio shows
that this mass is simply a tilted fragment of the reef thrown into its
present position by having been undermined at one end.

VOL. XLIV. 11

BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

= Time RELATIONS OF THE ELEVATIONS AND DEPRESSIONS.

Having presented evidence of both an elevation and a depression, it
remains to determine the order of these movements.

Inasmuch as the elevation recorded appears to have been a compara-
tively small one, two orders are possible : —

lst. An elevation greater than the one here described, followed by a
depression that returned the elevated coast to within a few metres of

its original position.

2d. A larger depression followed by a smaller elevation.

These two assumed orders of events can be tested by a process of
elimination by trying to explain thereby the conditions known to exist.

A section across one of the mangrove swamps shown on p. 150 is given

herewith : —

Fic. 90. Section across a mangrove swamp near Sio Thomé.

Case I.
and shell beds.

Hypothesis I.

Ist. Greater elevation.

2d. Smaller depression.

The elevation would allow the ero-
sion of the shell beds; the depression
would admit mangroves into the sub-
sequently drowned valleys. This re-
quires that the shell beds be first
deposited, which of itself requires a
still earlier depression.

Case II.

Hypothesis I.

The earlier elevation would have to
assume the shell bed already formed,
in which case the elevation would
leave it to be eroded and depressed
again.

Section across the north of Sao Thomé, mangrove swamp
See pp. 149-152.

Hypothesis II.

Ist. Greater depression.

2d. Smaller elevation.

The shells are deposited during the
depression ; the small elevation brings
them up where they are now being
eroded. In the swamps, the shallow
bay bottom is brought up within reach
of the plants.

Section across the Sao Thomé valley. See pp. 149-152.

Hypothesis II.

The greater depression would allow
the shell bed to be formed after the
depression, and slightly elevated later.

BRANNER: THE STONE REEFS OF BRAZIL. 163

Fig. 91. Section at the village of Sio Thomé.

Case III. Trachytic boulders (see p. 159).

Hypothesis I. Hypothesis IT.

The burrows would have to be The rocks were carried beneath the
made before the greater elevation, and water by the depression, then bur-
the following depression would bring —_ rowed, and later slightly elevated.
them within the reach of the water.

Fic. 92. Trachyte blocks bored by sea-urchins.

Case IV. has reference to the eroded coral reefs (see pp. 239-245).

Hypothesis I. Hypothesis IT,

Greater elevation would either have The depression would permit corals
to take place before the reefs were to grow up toa depth of 150’; a small
made, or else the reefs would all be elevation, when they were already
killed by the elevation. The depres- near the surface, would kill them and
sion would put them back in the allow them to be eroded.
water.

Case V. is that of the terrace at Ilheos spoken of on pp. 153-155.

Hypothesis I. Hypothesis IT.

Necessitates the formation of the The terrace was made during the
terrace before the elevation, and a depression, and lifted by a small
subsequent depression, elevation.

164 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

These cases all appear to favor the sccond hypothesis. It is a very
noticeable feature of the first hypothesis that it requires still earlier move-
ment and time for the formation of the deposits, while the second hypoth-
esis satisfactorily accounts for all the deposits with only two movements.

Taking the case of the Sao Thomé valley the sequence is also satis-
factorily established. A glance at the region shown in the sketch map
on p. 150 shows that it has had the following geographical history :
Subsequent to the deposition of the Tertiary beds, these rocks were com-
pressed more or less, lifted out of the water, and subjected to decom-
position and erosion that carved out rather steep-sided valleys. There
then followed a depression that admitted the water into the whole
region now covered by the Bay of Bahia—and a little more. The
upper ends of these valleys began at once to silt up with sands, shells,
and the like. After they were already considerably shoaled by this
process, there came a slight elevation that brought the shallow ends of
these valleys out of the water, and left them exposed on their margins
here and there to the action of the waves.

Thus the second hypothesis of a larger depression followed by a
smaller elevation appears to fit all cases, and for the present at least
must be considered as the correct one.

Influence of the coral reefs. — A factor that has been an important
one in controlling the outlines of the northeastern Brazilian coast is the
coral reefs. Their influence has been both protective and constructive.
There are included under this head, not only the corals proper, but
likewise the Serpulae and other lime-secreting organisms that live at-
tached to the rocks and reefs. Without such protection, the stone reefs
themselves would probably long ago have been obliterated.

The forms of the shores behind the reefs stand in evidence of the
great influence of the reefs upon these shores. Wherever there is a
reef of considerable length, a sand spit reaches out from the land to meet
it. Unfortunately the coast charts are not sufficiently detailed to show
this. On the ground it saut aux yeur.

The small harbors south of Pernambuco nearly all open behind breaks
in the reefs. That at Tamandaré is an example. North of the bay the
point on which Tamandaré stands approaches the coral reef north of a
break, while Ilhetas Point approaches it in the same way south of the
break, leaving the bay a semicircular one.

Maceio is another example, though in this case the harbor is behind
one end of the reef.

The coral reefs have already caused a general advance of the shores

BRANNER: THE STONE REEFS OF BRAZIL. 165

toward the sea, and in time the space between the reefs and the shores
must be closed, even without any alteration of level of the coast.

TAMANDARE

o
o2

‘PORT OF TAMANDARE

~ Coast of Pernambuco, Brazil,

Fort Santo Ignacio Lat 6°43 40°S Long 35°05 06" Ww

Scarce tn Mices:

Fic. 98.

It is a well-known fact among engineers that when headlands appear
above water, they are attacked by the waves, but at the same time they
cause a seaward advance of the shores behind them. This is well illus-

<
fio)
o
<4
~~
<x
i
°
Ss)
=
<
&
Y)

Scale

Fic. 94.

BRANNER: THE STONE REEFS OF BRAZIL. 167

trated by the behavior of the silts about any extension of jetties about
harbors.?

Influence of the mangues. —The various forms of tide-marsh vegeta-
tion, especially the mangrove swamps, have played an important part
in the turning of shallow waters into marshes, and later into land. So
far as I have observed, the mangrove plants thrive only on new and
growing land deposits. The plants are influential in preventing scour
by the tides, and in holding the silts and other accumulations together
until they can be seized upon by other plants. Their wide and ever-
spreading roots, the new plants started both from seeds and from roots,
the protection they offer to various forms of amphibian life, make of
these mangroves a geologic agency of the first importance in the tropics
on the borderland between fresh and salt water — between land and
sea. Most of the mangrove plants one sees near the streams are only
from three to five metres high. At Cannavieiras, however, there are
enormous forests of mangrove-trees from fifteen to twenty-five metres
high, and with large straight trunks rising upon their straddling roots.

Hyacinths. — In fresh waters the water hyacinth, known in Brazil as
Baroneza, is an important geologic agent, choking up streams and lakes,
depositing organic accumulations over the bottoms of these water bodies,
and even drifting out to sea, especially during the rainy season, in
enormous quantities.

Origin of the coast sands. —It is not altogether germane to the present
discussion to consider the origin of the sands that form the dunes and
beaches of the northern coast of Brazil, and the subject would not be
referred to here if there were not erroneous theories current regarding
these sands. I have heard it maintained and have seen it stated that
they were brought to Brazil from Africa by the equatorial currents ;?
and also that they come from the Amazonas. Bario de Capanema
thinks the sands of the coast of Ceara come from the Serra do Araripe.®

The carrying of the sands across the deep Atlantic is altogether out
of the question. Streams are unable to carry any but light sediments
across deep portions of their channels, to say nothing of the South
Atlantic current that moves at a rate of from one to two kilometres an

1 See cases of Calais and Dunkirk. Harbours and estuaries on sandy coasts.
By L. F. Vernon-Harcourt. Proc. Inst. Civ. Engs., 1881-2, LXX., p. 3, 6.

2 Thomaz Pompeo de Souza Brazil. Berthot and Moreau de Jonnes in Ensaio
Estatistico da Provincia do Ceara. p. 18, 49, 1863.

8 Trabalhos da Commissio Scientifica de Exploracio. I. Introducceio, CXXXV.
Rio de Janeiro, 1862.

168 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY.

hour, for four thousand seven hundred kilometres, and has a maximum
depth of more than four kilometres.

Mention may also be made in this connection of the fact that the
Atlantic basin between West Africa and Brazil contains no materials of
direct land origin except near the continental shores. The deep sea
bottom is covered elsewhere with red clay and organic (Globigerina)
ooze.?

As to the possibility of Amazonian sources, the question is one of the
shore currents and winds. But the currents along the northern coast
of Brazil set westward and northward, and unless there are in-shore
return currents, the sands brought down by the Amazonas cannot travel
southeastward. Besides, the methods of discharge of the streams north
of Cape Sao Roque (all of them bend northwestward and follow the
coast) indicate that the sands of the coast are moving northward rather
than southward.

The accompanying map showing the relief of the sea-floor out to the
100-fathom line has been constructed by drawing in contours from the
data on the hydrographic maps of the northeast coast of Brazil. This
map shows that the continental margin les from 25 to 35 miles off the
present shore. Over this shelf the water is rather uniform in depth.
The clean-cut shoulder about Cape St. Roque, where the eastern equa-
torial currents strikes it, and the gradual outward slope of this shoulder
toward the north, seem to suggest that the north-flowing current sweeps
in that direction the materials cut from the shores.

The fact is, that in the main the sands of the coast are of local origin.
They have simply been cut from the headlands and thrown back into
embayments, until the embayments were filled up, after which the en-
croaching sea has attacked these sands themselves and thrown them
upon the beaches, whence, when dry, they are swept up inland by the
on-shore winds that blow here the year round. The corallines, reef-build-
ing corals, and other lime-secreting organisms have also contributed enor-
mously to the recent sands of the coast, while the streams have all
brought down more or less sand from the land. An examination of the
sands made in June, July, and August, 1899, bears out this theory in
every detail. Along shores having corals reefs, the beach sands are cal-
careous ; where the coast rocks are granites, gneisses, or schists, the sands
are made of the minerals composing those rocks. The sands of the beach
opposite the island of Santo Aleixo are different from the sands found
anywhere else on the coast, but the rocks of Santo Aleixo are different

1 Challenger Reports. Deep-Sea Deposits. Chapter I. London, 1891.

BRANNER: THE STONE REEFS OF BRAZIL. 169

from the other rocks along the coast. A microscopic examination of the
Rio Formoso reef rock shows that the sand is derived from granites or
gneisses, — just such rocks as lie to the landward of the narrow strip of
Tertiary sediments that form the immediate coast at that place.

The theory of the transatlantic origin of the Brazilian sands seems
to have had some support from Elisée Reclus, who puts forward the
equally remarkable theory that the sediments swept into the Atlantic by
the Amazonas are deposited upon the coast of Georgia and the Carolinas.’
In such a case the Amazonian silts would have to cross some of the deep-
est places in the Atlantic Ocean, to say nothing of the flocculating and
precipitating influence of salt-water upon these sediments.

CONCLUSIONS REGARDING CoasT CHANGES.

1. There is no evidence of a perceptible change of level of the coast
since the discovery of Brazil.

2. Changes have taken place in the form of the coast-line, and in the
adjacent streams, bays, and estuaries in historic times, but they are all
accounted for by the ordinary processes now in operation.

3. The stone reefs are not metamorphosed or folded, and they do not
rise above tide-level, except in a few instances, where blocks have been
tilted by the undermining done by the waves.

4. The coast lakes have been formed by the damming in of estuaries,
by the sands blown along the coast, and by the throwing back into the
estuaries of detritus cut by waves from adjoining headlands or brought
down by streams from the land.

5. The straightness of the coast-line is due to the long period of wear-
ing to which the coast has been subjected, and to the constant on-shore
winds and waves along the coast.

6. During the dry season the waves of the sea are able to close the
mouths of many of the weaker streams.

7. At such times only the large streams are able to keep their mouths
boldly open.

8. Although no changes of level are known to have taken place within
the historic period, there are evidences of both elevation and depression
of the Brazilian coast in late geologic times.

9. The evidences of depression consist of : —

a. The open bays: Rio de Janeiro and Bahia.
b. The partly choked up bays, such as Santos and Victoria.

1 Blisée Reclus. Nouvelle géographie universelle. Tome XIX. Amérique du
Sud, p. 146-147, Paris, 1894.

170 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

c. The coast lakes formed by the closing of the mouths of estuaries
such as Lagoa Manguaba, Lagoa do Norte, Jiquia, Sinimbd, etc.

d. Embayments altogether filled up.

e. The islands along the coast are nearly all close in-shore and have
the appearance of having been formed by depression of the land.

f. The buried rock channels at Parahyba, now filled with mangrove
swamps and mud, show a depression of at least twelve metres
since those channels were cut.

g. Wind-bedded sand below tide-level on Fernando de Noronha.

10. The evidences of elevation consist of : —

a. Elevated sea beaches especially well shown about the Bay of
Bahia, and along the coast of the State of Bahia.

b. Marine terraces about Ilheos in the State of Bahia. These are
about eight metres above tide level.

c. Horizontal lines of disintegration about one metre above high
tide in granites and gneisses at and about Victoria, State of
Espirito Santo.

d. Burrows of sea-urchins so far above low tide that sea-urchins can
not now live in them. These are well shown at Pedras Pretas
on the goast of Pernambuco.

11. Of the two movements the depression has been much the greater
and was the earlier.

12. The great depression probably took place in early Pliocene times.
(See the chapter on Geology, pages 8 to 33.)

13. Following the Pliocene depression of the coast, the headlands were
strongly eroded, the mouths of bays and estuaries were closed, and the
coast line straightened.

14. The sandstone reefs of the coast were formed and hardened sub-
sequent to the depression.

15. The coral reefs of the coast have helped build out the shores, and
they have likewise protected the land from the destructive action of the
waves.

16. The stone reefs have also protected the land, and have helped to
prevent the encroachment of the sea.

17. The mangrove swamps have been important agents in building up
the newly formed land about estuaries and embayments.

18. The sands of the coast are not of foreign origin, as has been sur-
mised, but are derived from the adjoining headlands, or they have been
brought down from the land by streams.

BRANNER: THE STONE REEFS OF BRAZIL. v7 it

Wale

The Consolidation of the Stone Reefs.

PAGE PAGE
PHGIcementecmrssb ee ae LOL III. Lime carbonate from the
Analysis of therock. . . . . 172 landence se. (2. « 186
Microscopic examination . . . 1738 Consolidated beaches of
Origin of the cementing material 174 the Levant. ... . 187
I. Cement from beach sands Relations of density to deposition 190
by rain-water or spray. 175 IV. The seaward percolation
II. Lime carbonate from the of acid land-water . . 192
OCEGANG., acs... os a eee Possible influence of cli-
Co, of voleanic origin . . 178 MAtG renee, tc ok ss sy DS
Co, from sea-water . . . 182 The process not a continu-
Is the process universal? . 184 OUSYONE? cae ks ves, = LOE
@onclusions..<. 3). « - . . 195

~

Havine studied the forms and origin of the beaches, we may
now consider the process or processes by which they may have been
consolidated.

That the ancient forms of the beaches of which the stone reefs are
made have been preserved is due to the fact that the sands of these
beaches have been firmly cemented. Without the hardening, we should
have had no stone reefs, because the processes of beach changes would
have failed to leave these old shore lines outstanding: they would
either have been buried by later accumulations, or have been destroyed
by wave action.

THE CEMENT.

The hardening of the rock is due to the deposition of carbonate of
lime in the interstices of ordinary beach sands. This is shown by a
microscopic examination of fresh specimens of the rock (see page 173),
and by putting a piece of the rock in an acid that will remove the lime
carbonate.

A chemical analysis has been made of a sample of the Rio Formoso
reef rock, with the following results : —

172 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

ANALYSIS OF Rock FROM THE STONE REEF OF Rro FormMoso,
~ R. N. Brackett, ANALYST.

Specimen dried at 110° to 115° Centigrade.
Per Cent Per Cent

Matter soluble in concentrated hydrochloric acid 35.94
Matter insoluble in concentrated hydrochloric acid 64.06
Silica (Si0,) (nearly all quartz sand) . . . 63.52
Alumina CARO): . \. “s+: Et eee
Trom(He,0,)— 32 sieiglles fis *okanes. tee
Lime carbonate (CaCO, \ s- Sei [ckaey aig ammonia
Carbonate of magnesia (MgCO,) . . .. - 4.97
Phosphoric anhydride (P,0,)-- : - » = = ‘trace
Maonesia (MeO). 25. tN ce ees
Potash (CK5O)) a <0) ae ce
Soda GNa,O) 5. ny ee
Losson ignition = = = Te) fe ee ee

Total, ... i. 9. Set: WeReORtSa eaalae)

The analysis shows a rather high percentage of lime, but this lime
does not all come from the hardening material between sand grains.
The rock contains many pieces of shells, corals, and other calcareous
fragments, in addition to the lime deposited between the sand grains ;
it is not possible to entirely remove all of these shell fragments from
the material used in the analysis.

An analysis was made by Prof. L. R. Lenox of the binding material of
the Mamanguape reef rock. In order that the results of this analysis
may be compared with that of the Rio Formoso reef rock, the two are
put here side by side.

ANALYSES OF THE BrnpING MATERIAL OF STONE REEFS.

Rio Formoso rock. Mamanguape rock.

Lime (CaQ) "fe cS en 17.59
Magnesia (MgO) . i sans =. Sno weotoe 2.58
Equivalent to carbonate of Ea (Caco 3) 29.65 31.41
Carbonate of magnesium (MgCO,) . . 4.97 5.39

There is, therefore, a striking similarity in the binding materials of
the two rocks, though the specimens came from reefs more than two
hundred kilometres apart.

The hardening of the rock has been produced by the deposition of
lime carbonate and magnesium carbonate in the sands. When placed
in acid, the carbonate is soon dissolved, and the sand grains fall apart ;
second, a microscopic examination of thin sections of the rock shows

BRANNER: THE STONE REEFS OF BRAZIL. 173

that the spaces between the sand grains are filled with carbonate of
lime, and sometimes with a little hydroxide of iron. At a few places
the hardening is caused by iron, but these instances are purely local.

It is pointed out in the chapter upon the coral reefs that, when dead
coral skeletons are left for a long while saturated with Sea-water, some
of the lime is replaced by magnesia and that ultimately a dolomite or a
dolomitic limestone is formed. It is not known at present whether a
similar change takes place in the binding material of the rock of the
sandstone reefs. It may be that the original binding is what we find it
to be at present, namely, a dolomitic lime rock, or it may be that the
original binding material is carbonate of lime, which is partly replaced
by magnesium carbonate from the sea-water.

THe Microscopic EXAMINATION OF THIN SECTIONS OF SANDSTONE FROM
THE Rio Formoso Reers.}

Thin sections of these sandstones show in general, under the micro-
Scope, a rock made up of irregular grains of quartz and organic fragments
cemented together with calcite. (Noss, 2.3: 5: 6.)

The proportion of quartz to organic fragments varies within consider-
able limits in different sections. Besides the quartz, there are a few
irregular sections of a feldspar, probably orthoclase, as well as some
brown matter, which appears to be hydroxide of iron. Many of the
quartz grains are grown through with fine dark and light colored needles,
which may be rutile. Bright, strongly refracting, brilliantly polarizing
little crystals both in the quartz grains and in the cement between
them are believed to be zircons. Finally, there are in some of the
sections bright yellow irregular fragments the nature of which was not
determined.

The only mineral requiring a detailed description for the purpose in
hand, which is to find out, if possible, something in regard to the origin
of the material from which the sandstones were formed, is the quartz.

The quartz in thin sections occurs in large and small grains. An
apparently continuous large grain breaks out often under crossed nicols
into an aggregate of small grains showing different orientation. Some
of the large grains are cracked and filled in along the cracks, sometimes
with calcite and sometimes with hydroxide of iron. Most of the quartz
grains are quite full of inclusions. In some cases, a grain is grown

1 For this microscopic examination I am indebted to Dr. R. N. Brackett, of
Clemson College, S. C.

174 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

through in every direction with needles, which are colorless, brown,
black, highly refracting, when light colored, and are probably rutile.
In other instances, there are bright, highly refracting, colorless little
crystals that closely resemble and are believed to be zircons. Of all
the inclusions, by far the most abundant are irregular-shaped, round,
columnar, and dihexahedral bright little bodies, each usually surrounded
by a dark rim. They occur single, or arranged in lines or groups.
Some contain a single, movable bubble, and are liquid inclusions con-
taining a gas bubble. The bubble in a few cases was found to move
spontaneously, and to be constantly in motion. Others contain two or
more bubbles, and are then believed to be glass inclusions. The dihexa-
hedral bodies are negative quartz crystals, or holes having the shape
of a quartz crystal.

As to the bearing of the facts on the question of the origin of the
material from which these sandstones were formed, it may be said that
besides quartz, two constituents occur, one, feldspar, common to all
granites, and the other, biotite, belonging to certain classes of granites.

The quartz itself furnishes in its liquid and glass inclusions evidence
of its deep-seated origin and of its formation from a molten magma
under considerable pressure. This follows if the inclusions are, as is
believed, glass inclusions, and if the liquid inclusions contain gas bubbles,
such as carbon dioxide or some gas requiring pressure for liquefaction.
Besides, all the inclusions found in the quartz grains are quite character-
istic of and common in quartz grains found in granites and other rocks
formed at great depths and under considerable pressure. It is true that
both rutile and zircons are found in metamorphic schists, the former
being more characteristic of schists and other metamorphic rocks than
of rocks which are believed to have solidified from a molten magma.
But the glass inclusions certainly furnish evidence of crystallization from
a molten magma, and this, taken together with the liquid inclusions with
a gas bubble, make it quite probable that the material for the formation
of these sandstones is furnished by the disintegration of a granite or some
rock formed under similar conditions.

THE ORIGIN OF THE CEMENTING MATERIAL.

I conceive of four possible sources of the lime carbonate with which
the reef rocks are hardened, as follows : —

I. Dissolved by rain-water or spray from the beach sands them-
selves ; that is, carried from the upper layers of the sand and deposited
in the lower ones.

BRANNER: THE STONE REEFS OF BRAZIL. 175

II. Deposited from the ocean water after having been derived (through
the agency of carbon dioxide) from calcareous organic bodies in the sea.

III. Brought down from the land by streams. 5

IV. Dissolved from calcareous beach sands by fresh water streams
entering behind them, and redeposited while passing seaward through
these sands.

These sources will be considered in this order.

I. Cement from the beach sands by rain-water or spray.—The dis-
solving of lime carbonate by rain-water from the upper layers of cal-
careous sands, and its redeposition a little lower down, is a well-known
phenomenon. Woodward mentions instances of blown sands having
been hardened sufficiently by lime and iron to be used for building pur-
poses. This hardening is especially common in warm regions where
abundant molluscan life and coral-forming animals, calcareous Algae,
gorgonias, and the like so often contribute largely to the beach sands.
Aeolian sandstones and the sands upon the shores of coral islands are
often hardened by this process. But, so far as I can learn, and so far as
my own observations go, the rocks whose cements are derived from their
own beds in this fashion are so highly calcareous as to be practically
pure limestones.

The rocks of Bermuda are spoken of by Vetch, Nelson, Rice, Agassiz,
Thomson, and Heilprin as newly-formed limestones. Rice says, “The
cement which converts all these fragmental deposits into solid rock is
formed by the solution of the calcareous particles themselves,” ? and he
points out that these rocks are almost exclusively limestones derived
from shells and other calcareous fragments.

Sir Wyville Thomson says the sand of which the white granular
aeolian limestone is made “consists almost entirely of carbonate of lime.
.. - When rain .. . falls upon the surface of the sand, it takes up a
little lime in the form of bicarbonate, and then, as it sinks in, it loses
the carbonic acid and itself evaporates, and it leaves the previously dis-
solved carbonate of lime as a thin layer of cement, coating and uniting
together the grains of sand. . . . The extreme result is a compact,
marble-like limestone.” ®

1 H. B. Woodward, The geology of England and Wales, ed. 2, p. 546-547. Lon-
don, 1887.

The same author cites several instances of the induration of marine deposits
(p. 550-551).

2 Wm. North Rice, The geology of Bermuda. Bull. 25, U. S. Nat. Mus., p. 10.

Washington, 1884.
8 C. Wyville Thomson, The Atlantic. Vol. I., p. 291-295. New York, 1878.

176 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

I do not find that Mr. Alexander Agassiz mentions the precise process
by which the aeolian deposits were hardened, but it seems quite evident
throughout his paper on the Bermudas? that he thinks the sands are all
calcareous, of organic origin, and cemented on land by rain-water, after
having been blown up from the shores. Verrill lays stress upon “the
secondary infiltration . . . of calcium bicarbonate and the deposition of
calcite,” and he notes that “this zone of calcification ”’ would always be
higher than high tide-level.?

Jukes mentions the cementation of such calcareous sands by rain-
water® in Australia, and Dana speaks of similar phenomena on the
Hawaiian Islands.‘

“At King George’s Sound in Australia... the upper layers...
have been hardened by the action of rain on the friable calcareous
matter, and the whole mass has originated in the decay of minutely com-
minuted sea shells and corals.” ®

Many cases have been noted of the consolidation of beach sands by
ocean spray blowing over them. On the island of St. Croix mention is
made of shells and other substances, including iron utensils on shore,
having spray charged with calcareous matter dasbed over them. ‘ These
generally unite and harden, especially near the surface, and form into a
tolerably compact mass.” ® Evidently the hard rocks are in process of
formation.

The only analyses seen of the beach-hardened calcareous sandstones
are those given by the writer. These are of the aeolian sandstones of the
islands of Fernando de Noronha. They show those rocks to contain, in
one case, 98 per cent of lime carbonate and less than one per cent of

1 A visit to the Bermudas in March, 1894. Bull. Mus. Comp. Zool., XXVLI.,
Ne. 2. Cambridge, 1895.

2 A. E. Verrill, Notes on the geology of Bermuda. Amer. Journ. Sci., 4th Ser.,
TX., May, 1900, p. 321.

Captain Vetch, in Trans. Geol. Soc., 2d Ser., I, p. 172. London, 1824.

On the calcareous sandstones of the Bermudas, see also Richard J. Nelson,
Trans. Geol. Soc. London, 1840, V., p. 103-123.

A. Heilprin, The Bermuda Islands, p. 80-32. Philadelphia, 1889.

J. Walter Fewkes, On the origin of the present form of the Bermudas. Proc.
Bost. Soc. Nat. Hist., 1888, X-XIIL, p. 518-522.

3 J. Beete Jukes, Narrative of the surveying voyage of the H. M. S. “ Fly.”
Vol. I., p. 9; 128; 339. London, 1847.

4 J. D. Dana, Corals and coral islands, ed. 3, p. 155. New York [1890].

5 Darwin, Geological Observations, ed. 2, p. 248. London, 1876.

6 §. Hovey, The Geology of St. Croix. Amer. Journ. Sci. XXXV., p. 72.
New Haven, 1889.

BRANNER: THE STONE REEFS OF BRAZIL. ATT

silica ; in another instance, the analysis showed 97 per cent of lime
carbonate and two per cent of silica.’

The analysis of the Brazilian reef rock, on the other hand, shows that
it is made up of about two parts of silica to one of lime carbonate,
including both cementing material and shell fragments.

It does not seem improbable, judging solely from the amount of lime
carbonate in the rock, that the cementing materials may have come from
these same sands, having been dissolved from one part of the beds and
deposited in another.

II. Lime carbonate from the ocean. — Hartt long ago suggested that
the lime carbonate by which the reef rocks are hardened was deposited
from sea-water.?_ Such an explanation, however, can be looked upon as
satisfactory only when it is accompanied by some explanation of the
source of the lime, and the method and process of its deposition. It
may well be objected to this theory that the beach sands in many parts
of the world are quite as calcareous as those of northeastern Brazil, that
the surf breaks upon these sands in the same way as it does upon the
Brazilian beaches, and yet they are not hardened by the deposition of
lime carbonate. Evidently a satisfactory explanation should deal with
this part of the problem.

The theory of the process of hardening by lime carbonate from the
ocean water is briefly: that the carbon dioxide escapes where the surf
breaks upon the seashore, just as it escapes from streams at cataracts, or
wherever a disturbance throws the lime-charged waters into spray, or in
any way lets the air at the water.? Such surf should precipitate both
lime carbonate and iron, the latter being in solution as ferric car-
bonate, and being precipitated as ferric oxide. The lime is thought
to be held in solution as a bicarbonate, and to be deposited as a lime
carbonate.

What is the source of the carbonic acid necessary to form the lime
carbonate with which the Brazilian reef sands are hardened ?

And why is this process of lithification not a universal one ?

I conceive of two methods by which the carbon dioxide might come
from the ocean. 1. By submarine discharge of CO, of volcanic origin.
2. CO, derived from the sea-water itself.

1 Amer. Journ. Sci., April, 1890; XXXIX., p. 249-256.
* Ch. Fred. Hartt, Geology and physical geography of Brazil, p. 343. Boston,
1870. Amer. Nat., June, 1879, XIII., p. 347-358.
8 George Murray, in his Introduction to the study of seaweeds, p. 8, points out
that air introduced into or passed through sea-water carries off carbon dioxide.
VOL. XLIV. 12

178 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

Carbon dioxide of submarine volcanic origin. —The carbon dioxide
ordinarily found in the sea is not free but combined in carbonates and
bicarbonates.

In the case of carbon dioxide of volcanic origin discharged in the sea,
it might remain chemically dissolved in the water, (CH,O + CO.) =
(H, COg), but as soon as it came in contact with calcium or magnesium,
the carbon dioxide would dissolve the lime carbonate, whether in the
calcareous shells of living mollusks, corals, and crustaceans, or in the
broken fragments of dead ones on or near the shores. A bicarbonate
would be formed and held in solution until precipitated out or other-
wise removed as a carbonate.

It is but natural that one should object at the outset to a theory that
seems to be so far-fetched — to a source so out of the ordinary course of
events as does the one here suggested. But the source is really not so
extraordinary as it at first appears.

The most valuable observations upon the gases emitted by volcanic
eruptions with which I am acquainted is that of Fouqué upon “ Santorin
et ses eruptions,” published at Paris in 1879. In his study of that
interesting locality M. Fouqué found that —

a. The carbonic acid discharges became more and more marked after
the seasons of greatest volcanic activity.

b. That the compositions and temperatures of gases were but little
affected by passing through waters (p. 229).

c. That variation of the gases is the same for subaqueous as for
subaerial volcanoes (p. viii).

The pouring out of volcanic eruptions beneath the ocean is not an
uncommon occurrence. Indeed, Sir Archibald Geikie lately remarked
that “‘ With regard to the supposed impossibility of lavas having flowed
under the sea, he could only observe that no facts in the geological
history of Britain were more abundantly proved than that from the
earliest Palaeozoic periods the vast majority of the volcanic eruptions in
our region have been submarine.” 1. . . Sometimes the products of these
eruptions rise above the water’s surface, forming islands, as in the cases
of Graham’s Island in the Mediterranean Sea,? islands off the west coast
of Iceland, and Bogoslof off the island of Unalaska.

The island of Bogoslof, as it is now called, was first described by
Langsdorff. He says that in 1795 the people of Unalaska observed the

1 Quar. Journ. Geol. Soc., May, 1898, LIV., p. 233.
2 H. J. Johnston-Lavis. For bibliography of this island, see The south Italian
volcanoes, p. 105-107. Naples, 1891.

BRANNER: THE STONE REEFS OF BRAZIL. 179

appearance of a fog in the vicinity of the rock, and upon visiting it they
found “ the sea all about the rock boiled, and that the supposed fog was
the smoke or vapour that rose from it.” After about five years the fog
cleared away, and fire and smoke were seen issuing froma peak upon the
island. At the time of Langsdorff’s visit in 1806, the lava was still
running from the island into the sea, and the sides of the peak were
hot.* These and other cases of submarine eruptions are cited by Scrope.?
Mr. W.G. Foster of Zante, Greece, has also called attention to evidences
of submarine eruptions afforded by the burning of submarine cables.®
These eruptions did not reach the surface of the seas. Dr. Sambon tells
of the breaking of cables by submarine eruptions on several different
occasions, of the boiling of the sea, and of the escape of gases 4 through
the sea-water.

Sainte-Claire Deville ® found carbonic acid emerging lower down on
Vesuvius than ammoniacal gases, toward the end of an active period of
eruption, and always cold. He considers these discharges as an effect
and as the last act of eruptions.

Fouqué’s later and more extended studies “confirm the law of the
variation of voleanic gases first established by Ch. Sainte-Claire Deville.” ®
He also found that the law in regard to the order of discharge of the
various gases is the same for submarine as for subaerial volcanoes.” By
direct observation he ascertained that from 4 to 88 per cent of the gases
obtained from the fumaroles of Santorin were carbonic acid. This gas
escapes even when volcanic activity is dormant, and in some cases accu-
mulates in considerable quantities in depressions such as the Valley of
Death in Java, where animals are often suffocated. ‘In Java there is a
crater, called the ‘Guevo Upas,’ or ‘ Poison Valley,’ half a mile in cir-
cumterence, always so full of carbonic acid gas that every living thing
that passes its limits is suffocated, and the ground is strewed with the

1 G. H. von Langsdorff. Voyages and travels in various parts of the world,
Part IIL., p. 242-245. London, 1814.

W.H. Dall. A new volcanic island in Alaska. Science, Jan. 25, 1884, III.,
p. 89-93.

I. C. Russell. Volcanoes of North America, p. 276-281. New York, 1897.

Kotzebue’s Voyage of discovery, Vol. III., p. 287. London, 1821.

2 G. Poulett Scrope. Volcanoes, ed. 2, p. 236-238, London, 1862.

3 Trans. Seismological Society of Japan, Vol. XV., p- 78. Yokohama, 1890.

4 L. Sambon. Notes on the Eolian Islands and on pumice stone. The South
Italian volcanoes. Edited by H. J. Johnston-Lavis. p. 64-65. Naples, 1891.

5 Bull. Soc. Géol. de France, XIII. ser. 2, p. 640. Paris, 1855-6.

® F. Fouqué. Santorin et ses eruptions, p. 232. Paris, 1879.

7 Op. cit., p. viii. 8 Op. cit., p. 225.

180 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY.

carcases of wild animals, birds, and even of men that have met their fate
there. . . . Exhalations of carbonic acid gas occur abundantly in many
other districts which were the former seats of volcanic action.” . . .1

In Death Gulch, Yellowstone National Park, a volcanic region, it rises
from the waters to such an extent as to suffocate wild animals, — even
grizzly bears.”

Fouqué shows that within certain limits carbonic acid is emitted about
volcanoes in larger proportions as one leaves the more active vents, and
Sainte-Claire Deville shows it to be a prominent gas of fumaroles.? Sir
William Hamilton speaks of noxious gases about Vesuvius killing birds
and other animals, and even persons.* Some of these gases seem to act
like carbon dioxide.

Daubeny refers to these gases, and says that they are supposed to
consist chiefly of carbonic acid gas.® In another place he states that
“carbonic acid is a common product of volcanoes nearly extinct ; it is
emitted, as we have seen, very abundantly from fissures in the neighbor-
hood of Naples, as well as near Rome, in the Vivarais, in the Eyfel....
It is supposed that the Mofettes, which often succeed an eruption of
Vesuvius, consist of this gas; but it is remarkable that during a state
of vigorous action this volcano does not appear to emit it.” °

Dr. Johnston-Layis tells of the escape of carbon dioxide from springs
of Sujo and from other openings in the vicinity of Roccamofina (between
Rome and Naples) in sufficient quantities to suffocate human beings.’

Now we have satisfactory evidence in the Fernando de Noronha group
of islands of volcanic activities off the northeast coast of Brazil. This
group lies two hundred miles northeast of Cape St. Roque, and, with the
exception of certain small areas of eolian sandstones, is made up entirely
of eruptive rocks.®

1 G. Poulett Serope. Volcanoes; the character of their phenomena, etc., ed. 2,
p- 151-152. London, 1862.

2 T. A. Jagger, Jr. Death Gulch, a natural bear-trap. Pop. Sci. Monthly, Feb ,
1899.

Ward in Science, March 24, 1899, p. 459.

8 Russell’s Volcanoes, p. 52.

4 Wm. Hamilton, Observations on Vesuvius, Mount Etna, and other volcanoes.
p. 164-167. London, 1774.

5 Charles Daubeny. A description of active and extinct volcanoes, p. 161.
London, 1826.

6 Op. cit., p. 875.

7 H. J. Johnston-Lavis. The south Italian volcanoes, p. 77-79, and plate xvi.
Naples, 1891.

8 J. C. Branner. The geology of Fernando de Noronha. Amer. Journ. Sci.,
1889, XXXVII., p. 145-161.

italic ince,

BRANNER: THE STONE REEFS OF BRAZIL. 181

We have no means of determining the age of the rocks of these islands,
but the freshness of the lavas and the rapidity with which the shores are
being eroded by wave action lead us to infer that they are new."

The position of these eruptive islands affords a basis for the theory
that either at the time of the extrusion of the rocks that form the group,
or at some subsequent eruption, large quantities of carbon dioxide may
have escaped into the sea. The South Atlantic current at this latitude
flows westward, but during eight months of the year (October to May,
inclusive) the northeast trade winds shift it somewhat toward the south,
so that during those months the oceanic currents that pass Fernando
flow toward Cape St. Roque, and thence pass southward along the east
coast of Brazil, past Rio Grande do Norte, Pernambuco, Rio Formoso,
Bahia, etc. These currents would have thrown the carbon dioxide, had
they contained it, against the shores along the northeast coast of Brazil
from Cape St. Roque southward.

But if submarine discharges of carbon dioxide have taken place, and if
beach sands have been hardened as here suggested, we may reasonably
expect to find beach sands similarly consolidated in other parts of the
world. There are indeed many cases known of the hardening of recent
beach sands. In only two instances, however, do they appear to have
been hardened by carbon dioxide escaping from submarine vents: these
are in the Straits of Messina between Sicily and Italy, and on the shores
of the Red Sea.? In both of these cases the consolidation has taken
place in the vicinity of volcanic activity.

We seem warranted in the conclusions that carbon dioxide of volcanic
origin is discharged beneath the sea; that it is competent to cause the
hardening of beach sands; and that the existence of a volcanic island
off the northeast coast of Brazil makes it possible that such discharges
may have taken place there. But inasmuch as the lithification of the
coast sands of the region is in various stages of development, and as

1 Northwest of Fernando de Noronha and eighty miles away is another small
island known as the Rocas. This island is about two miles long (east-west) by one
and three-fourths miles wide, and was until lately uninhabited. I have never
visited the place, but from information kindly furnished me by Commandante
Huet Bacellar, of the Brazilian navy, who has visited the place, I conclude that
the rocks there are corals. But whether the corals have igneous rocks beneath
them, I have been unable to learn. Except some dunes on the southwest corner,
it is all covered by water at high tide. On the Rocas, see p. 226-227 of this report.

2 Hawkshaw, Quar. Journ. Geol. Soc., 1879, XXXV., p. 242.

Suess says history mentions many eruptions on the Red Sea. Face de la Terre,
Dp. 478, note.

182 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

there are in many places several reefs overlapping each other, it seems
probable that the process on the Brazilian coast is an approximately con-
tinuous one to which this method of derivation is hardly applicable.

Carbon dioxide from sea-water, but not of eruptive origin. — Analyses
of sea-water show that it contains carbon dioxide in considerable but
varying quantities. It is most abundant in the cold waters of polar
regions and of the deepest oceans.

Dittmar says the atmosphere and the decay of organisms supply this
carbon dioxide, but he seems to think that most of it issues, like sub-
marine springs, beneath the ocean waters.’

Knudsen thinks that ‘predominance of animal or vegetable life in
any part of the sea causes the variations in the amount of contained
oxygen or carbonic acid.” ?

In studying this matter we should not lose sight of the fact that
marine animals having lime carbonate skeletons do not derive that lime
carbonate directly from the water, but they must get it through the
agency or interposition of the plants they use for food; that is, the
plants take it from the water and deliver it to the animals. We need
not especially concern ourselves, however, with the source of supply ; for
present purposes the fact of prime importance is this difference in car-
bon dioxide contents between the polar and tropical sea-waters, and the
general tendency of the carbonates to accumulate at the equator.®

Whatever may be its cause, there is then a general tendency for car-
bon dioxide to be taken up about the poles and liberated in the tropics.
Dr. John Murray pointed out in 1889 how the organic matter in the
ocean is attacked and dissolved by sea-water. “As soon as life loses its
hold on the coral structures, and wherever these dead carbonate of lime
remains are unprotected . . . they are silently, surely, and steadily re-
moved in solution.”* The methods by which the sea-water gets access
to the calcareous particles can be seen along coral reefs and in sim-
ilar shallow seas during a gale. The waters are affected to a greater
depth than usual, and the softer debris over the bottom is stirred up and
mixed with the water, giving it a milky appearance. Under such cir-
cumstances, the calcareous particles are exposed to the water through
its entire depth.

1 Report on the scientific results of the exploring voyage of H. M. S. “Chal-
lenger.”” Physics and Chemistry, I., p. 215. London, 1884.

2 Nature, June 30, 1898, LVIII., p. 201.

3 On the distribution of diatoms in polar seas, see An introduction to the study

of seaweeds, by George Murray, p. 19, 197. London, 1896.
* Nature, 1889, XXXIX., p. 424.

BRANNER: THE STONE REEFS OF BRAZIL. 183

That the deep cold ocean waters dissolve lime deposits readily is dis-
tinctly shown by the fact that deep dredging brings up little or nothing
in the way of calcareous shells and bones, and of sharks’ teeth only the
hard dentine, and only the hard earbones of whales, while the larger
bones have been dissolved. The chemical process involved seems to
be the formation of bicarbonates, and later the deposition of carbonates
upon the liberation of carbon dioxide.

In ordinary chemical laboratory work it is the practice to precipitate
carbonates from solutions by raising their temperatures. In such cases
it is understood that a part of the carbon dioxide is driven off by the
increase of temperature, while the lime or magnesia is precipitated as a
carbonate. This increase of temperature is not necessarily great, — not
near the boiling point. Similar increase of the temperature of ocean
waters is produced by the waters breaking in surf or rolling upon the
warm sandy beaches of the tropics. The whole process results, therefore,
in a general tendency for the carbonates to accumulate in the tropics.
But this accumulation must take place at or near the surface of the
waters, for the coldness and the pressure at great depths would keep the
carbonic acid free.‘ Only when the pressure is relieved, and the temper-
ature raised near the surface, is there any opportunity for combination
and for the formation of carbonates.

Waters carried from a cold sea into a warm one, or from the cold
depths to the surface and warmed suddenly, would yield up their car-
bonic acid contents. The form of the continental shoulder of northeast
Brazil, and the on-shore direction of the currents, favor this process.
The accompanying map (Plate 1) gives in contours the relief of the sea
floor along the Brazilian coast out to the one-thousand-fathom line.
This map shows that the continental margin lies only from twenty-five
to thirty-five miles off the shore. When the oceanic currents strike this
steep submarine escarpment, the colder waters are swept up from the
depths, quickly warmed at the surface, and made ready to yield up their
carbonic acid contents. Observations upon the waters themselves bear
out this view.

Waters of the Atlantic Ocean between Fernando de Noronha and Per-
nambuco vary in temperature from 30° at five hundred fathoms to 78°
at the surface.” In general the surface layer of warm water is thicker

1 The Prince of Monaco says Dr. Jules Richard found that gases “are not dis-
solved in the depths at any other pressure than they are at the surface.” Nature,
June 30, 1898, LVIIL., p. 201.

2 Challenger Reports. Phys. and Chem. I. pt. I, Plate 78. London, 1884.

184 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

on the east shore of a continent than on the west shore,’ and as Murray
points out, this favors the growth of corals along the eastern shores of
the continents. It must also favor the yielding up of carbon dioxide.
The conclusion seems warranted from these facts that the warming of
the sea-water of the South Atlantic equatorial current that sets against
the northeast coast of Brazil is capable of supplying all the carbon
dioxide necessary for the hardening of the stone reefs.

Is the process universal ?— But if the hardening of these beaches is
produced by the sea-water alone, why is it that the process is not a uni-
versal one, at least in the tropics ?

From what has gone before, it might appear that it was simply a mat-
ter of carbon dioxide, either of volcanic origin or derived from cold sea-
waters by warming them, in which case we might expect such beaches
in almost any part of the world.

Now the relations of ocean currents and temperatures to carbonic acid
are not new, but must have existed for a long time. If the sands of
tropical shores have been consolidated by the aid of carbonic acid brought
in by ocean currents, this process of consolidation must have been going
on ever since the present currents: were established, and it must be
going on to-day. Confining ourselves to the Brazilian coast, we should
expect to find, therefore, not a single or double line of stone reefs, but a
continuous series of hardened beaches overlapping each other, wherever
the coast line has been extended seaward by accretion, or exposed wher-
ever the ocean tends to encroach upon the land. As a matter of fact,
this is not the case in Brazil.

Dr. Dall says? that in Florida “ Coquina rock, frequently composed
more of sand grains than of shell, . . . is doubtless being formed at
many points along the Gulf shore, though in small quantities at each
place, and not at all in the lagoons and harbors.”” He mentions a recent
rock that contains land and marine shells, in some places soft and in
other places (without fossils) ringing under the hammer. What cements
this rock he does not state. Another is said to be hardened by iron
brought out in spring waters; still another is hardened by lime coating
the sand grains. (Loc. cit., p. 164.)

In order to ascertain whether recently consolidated beaches were
known about the British Isles, I have corresponded with Mr. W. Whita-
ker, lately President of the Geological Society of London, and some

1 Murray and Irvine. Nature. June 12, 1890. XLIL, p. 163.
2 W. H. Dall, Notes on the geology of Florida. Amer. Journ. Sci., 3d ser.,
XXXIV., p. 163.

BRANNER: THE STONE REEFS OF BRAZIL. 185

time member of the committee of the British Association, ‘‘ appointed
for the purpose of inquiring into the rate of erosion of the sea-coasts of
England and Wales.” * So far as his own observations go, Mr. Whitaker
tells me that he does not recall a single case of the hardening of beach
sands. He gives me, however, the following interesting unpublished
note made by Bauerman, in connection with one of Mr. Whitaker’s
papers on the Alderley Edge Copper-works, written in 1861 or 1862 :—

“ A curious deposit of a similar character has been noted in Cornwall, at the
Perran Mine near St. Agnes. The slow oxidation of small quantities of cop-
per-pyrites in the wash heaps of the old works, which rest upon blown sand,
produced soluble copper salts which were infiltrated by the rain into the sand
below, producing irregular concretionary masses cemented together by green
carbonate of copper. Many of the larger modules contained quartz pebbles
and snail shells. These sands were worked as copper-ores in the year 1853.”

There must be more or less of the hardening of beach sands, however,
on almost all shores during the summer months where the shallow
waters are warmed by thesun. But unless this hardening passes a cer-
tain amount, it can never produce perceptible effects, because storm-
waves during the rest of the year break up this incipient consolidation.
In the tropics this sort of deposits is more common.

“‘At many points on a reef where evaporation takes place, there is a
deposition of amorphous carbonate of lime cementing the whole reef
materials into a compact conglomerate-like rock.” These consolidated
beaches, however, appear to be local rather than widespread, even in the
tropics.®

If the preceding facts were the only ones concerned in the inorganic
deposition of lime carbonate, we might reasonably expect to find the

1 Report of the British Assoc. Adv. Sci. for 1885, p. 402-442.

W. Whitaker, Chronological list of works on the coast changes and shore depos-
its of England and Wales. Rept. Brit. Assoc., 1885, p. 442-465.

W. Whitaker, Second chronological list, ete. Rept. Brit. Assoc., 1895, p. 388-
402.

2 Murray. Nature. Feb., 1889, XXXIX., p. 427.

8 For other examples of the consolidation of beach sand by sea-water, see “A
voyage of discovery into the South Sea,” etc., by Otto von Kotzebue. IIL., p. 382.
London, 1821.

James D. Dana, Corals and coral islands, 152. New York, 1890. Amer. Journ.
Sci., 1885, CX XX., p. 108.

James D. Dana, Points in the geological history of the islands Maui, and Oahu.
Amer. Journ. Sci., 3d ser., XXX VII. 1889, p. 89.

A. Agassiz, A visit to the Great Barrier Reef of Australia. Bull. Mus. Comp.
Zool., XX VII., No. 4, p. 108, and Plate IV. Cambridge, 1898.

186 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

beaches of all tropical seas solidified by lime deposits. It is unnecessary
to say that such is not the case. So far as mere temperature goes, the
surface waters along the northeast coast of Brazil are probably neither
warmer nor colder than those along the shores in many other places
within the tropics. And yet the northeast coast of Brazil is almost the
only one along which the beaches have been extensively solidified.

In view of the exceptional character and extent of the stone reefs of
Brazil, it must be admitted that the theory of the deposition in them of
lime carbonate, due solely to the increase of the temperature of the water,
is not satisfactory.

III. Lime carbonate from the land. — Waters flowing from a land sur-
face of limestone would necessarily be charged with lime. If such
streams entered the sea without other dilution, there would be a ten-
dency for them to deposit their lime contents immediately upon entering
the sea. This precipitation is due to the saturated condition of the two
waters. The Rhone, emptying its strong lime waters into the Mediter-
ranean Sea, deposits lime with its silts, and the beaches about its mouth
are in many places consolidated. Lyell remarks, in speaking of this mat-
ter: ‘If the number of mineral springs charged with carbonate of lime
which fall into the Rhone and its feeders in different parts of France be
considered, we shall feel no surprise at the lapidification of the newly
deposited sediment in this delta.”?

The rocks of western Palestine and of southern Asia Minor are made
up almost entirely of limestone, so that the streams flowing from that
land surface enter the already dense waters of the Mediterranean Sea
heavily charged with lime, and the precipitation of that lime on the
shores has made the reefs and consolidated beaches described by Beau-
fort,? Botta,® Lartet,* and Hull.®

Inasmuch as the stone reefs of the Levant seem to be about the only
extensive ones inthe world comparable with those of northeast Brazil, it
seems best to give here some account of them and of the conditions un-
der which they appear to have been formed, in the hope of getting light
upon the Brazilian stone reefs.

1 Charles Lyell, Principles of geology, ed. 11, I., p. 426. New York, 1889.

2 F. Beaufort. Karamania, p. 10, 13, 174, 178, 207, 211, 212, 258, 289. On lime
in the streams, p. 180, 185-186, 141, 191, ed. 2. London, 1818.

3 Observations sur le Liban, etc. Mem. Soc. Géol., France, ed. 1, p. 185-160.

4 L. Lartet. Exploration géologique de la Mer Morte. Paris, 1877.

5 —. Hull. The survey of Western Palestine. Physical geology and geography.
London, 1886.

BRANNER: THE STONE REEFS OF BRAZIL. 187

The consolidated beaches of the Levant. — The earliest descriptions of
the reefs of Asia Minor known to the writer are those given by Francis
Beaufort. He is quoted here at some length (p. 182-186) : —

“The shore bounding this plain was once a gravel beach; but from the
upper part of the slope to some distance into the sea, it is now a solid crust of
pudding stone, from one to two feet in thickness. This petrified beach is not
peculiar to the plain of Selinty ; many instances of it on a smaller scale had
been already observed on the coasts of Asia Minor, and a few on those of
Greece ; and I have been informed that an example of it occurs also in Sicily.
Being generally covered with loose sand and pebbles, it presents to the eye no
extraordinary appearance. . . . The specimens that I have examined, taken
from various places, differ but little from each other; gravel predominates in
some, coarse sand in others, or they lie in alternate layers of each. . . . The
cement or paste by which they are united is likewise calcareous ; and so tena-
cious that a blow sufficient to break the mass, more frequently fractures even
the quartz pebbles than dislodges them from the bed.

“Close to the westward of Side we had found some ledges of rock, partly
above and partly under water, which appear to have been produced in a similar
manner : they contain a large proportion of broken tiles, both red and yellow,
of shells, bits of wood, and of such rubbish as might be expected in the vicinity
of a town... . At Phaselis also we found a patch of petrified beach; and
again at a few miles to the eastward of Alaya. ... It is needless to enu-
merate here all the places where it may be found on this coast.”

On page 249 this writer gives a small map of Pompeiopolis in which
the ancient port is shown to have been filled up with blown sands, and
these sands have become solidified on the beach within the port. (See
also p. 260.)

The last case shows that the hardening of the beach has taken place
within historic times.

Beaufort’s description of these beaches refers to the southern coast of
Asia Minor from the Island of Rhodes eastward.

Along the coast of Palestine these same phenomena are reported by
Botta.2_ His description of the reefs is given as a postscript to the article
proper, as follows : —

“P. S. Since this memoir was written I bave gone to see a fact first
pointed out to me by Dr. Hedenborg. Along the whole coast of Beirout or
El Arich to Tripoli is found a kind of conglomerate or argillaceous sandstone

1 Francis Beaufort. Karamania, or a brief description of the south coast of
Asia Minor, ed. 2. London, 1818.

2 P. E. Botta Fils. Observations sur le Liban et L’Antiliban. Mém. Soe. Geol.
de France, Tome I., p. 135-160. Paris, 1853.

188 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

of varying coarseness which, in his opinion as well as my own, is a late for-
mation. They generally occur as breakers (ecueils) along sandy coasts always
below high tide and without any connection with the limestone of the coast.
My specimens were collected in a small sandy bay between Beirout and
Antours, near a café called Donkhane el Doubbait. The conglomerates there
are in small irregular beds, always horizontal, washed by the sea, in the midst
of sands exactly like the rocks. This deposit gradually obstructs the ports of
the coast, and though there are no corals or madrepores on this coast, it forms
some small ports similar to those found among the coral banks and islands of
the South Sea ; such are those at Sour (Tyre) and at Jaffa. When they come
from the water they are not very solid, but they become very hard when ex-
posed to the air, so that a great many houses along the coast are built of it.
As at Saide, Sour (Tyre), Jaffa el Arich, etc., on the coast of Djibaii, I have
seen some yellowish varieties that looked to me quite similar to the conglom-
erates that I have seen at Palermo and at Messina, and which are generally
known to be still in process of formation. I have not found any containing
whole shells, and this is in keeping with their variety on these shores, but one
of the specimens has fragments still quite fresh. Among the grains some are
siliceous, others calcareous. The cement that unites them seems to be of the
latter kind. In size, they vary from that of an apple to that of the finest sand.
In considering the position and nature of these conglomerates, and in comparing
them with what I have seen elsewhere, I am convinced of their recent for-
mation. At the same time I am led to believe that it is alternative, that is to
say, that it does not occur constantly, for they are generally arranged in beds
and these are of different hardnesses like those of the trunk of a tree.”

Still later Lartet! mentions these Palestine reefs : —

“On this coast of Phonicia and parallel with the shore are lines of rocks
forming breakwaters in some places and in others very dangerous rocks. It is
doubtless on account of an upward movement that these hardened sand banks
rise to and appear above the water.

“Tn going ashore at Jaffa we were obliged to go through a dangerous passage
in the breakers that rise a little above the sea. . . .

“These sandstones of recent date form beds that follow the coast regularly
at a certain distance from the shore and generally rise just to the surface of the
water. . . . The calcareous sandstones usually make along the sandy shores
(lines of) rocks below high-water mark that are composed of the same materials
as the beach sand and sometimes contain some horizontal and irregular beds of
conglomerate.

‘« According to Botta, these deposits gradually obstruct the ports of the coast,
and though there are no corals or madrepores there, they form small ports like
those among the coral banks and islands of the South Sea. As soon as they

11. Lartet. Exploration géologique de la Mer Morte de la Palestine, p. 199.
Paris, 1887.

BRANNER: THE STONE REEFS OF BRAZIL. 189

are exposed to the air, the rock hardens and is used as we have seen as a build-
ing stone at Sidon, Tyre, Jaffa, and Asrisch. The shores of the Red Sea are
producing analogous marine formation, and the ports are being partly obstructed
by the development and slow elevation of the coral reefs.”

What seems to be a continuation of the same reef at Jaffa is thus
described by Hull:?—

“ A natural breakwater of calcareous sandstone projects outwards into the
Mediterranean from the ancient walls at the south end of the town (of Jaffa).
Outside this all large ships are obliged to cast anchor, and passengers as well
as cargoes have to be received and discharged by means of boats, which fre-
quently have to breast a heavy surf. The rock is seen under the lens to be
composed of comminuted shells, pieces of coral, and other marine forms ; and
it appeared to me to be of recent formation, raised into the air when the whole
sea-bed was being elevated. A similar formation of shelly limestone appears
to be in process of consolidation along the shore further towards the north,
where it is quarried just under the sands at the margin of low water. The
shells of which it is formed are those which strew the shore in immense num-
bers, chiefly those of Pectunculus glycineris.”

The preceding descriptions of the reefs of the Levant show that they
bear some resemblance to the stone reefs of Brazil. They follow the
coast line closely, and have been produced by the recent hardening of
beach sands by the deposition of lime carbonate.

Mention has been made of consolidated beaches upon the shores of
the Red Sea. Hawkshaw barely speaks of having seen such beaches.”
Dr. Buist speaks of elevated beaches on the shores of the Red Sea,®
and the rocks of the region are said to be ““nummulite limestone.” He
observes, however, that there is not a stream along its shores (p. 280),
—a matter of importance in connection with the present discussion.

In his paper upon “ Pleistocene shells from the raised beach deposits
of the Red Sea,” Mr. R. Bullen Newton * mentions many raised beaches,
some of them having an elevation of as much as 560 feet above sea-level,
but his paper is a palaeontologic one, and nothing is said of the condition
of the materials forming these old beaches.

In a later article by Dr. Hume,® mention is made of elevated beaches

1 Edward Hull. Mount Seir, Sinai and Western Palestine, p. 148. London,
1889.

2 Quar. Journ. Geol. Soc., 1879, XXXV., p. 242.

8 Buist. On the physical geography of the Red Sea. Journ. Roy. Geog. Soc.,
XXIV., p. 227-238. London, 1854.

* Geol. Mag., Nov. and Dec., 1900.
5 W.F. Hume. Geology of Eastern Sinai. Geol. Mag., 1901, VIII., p. 200-204.

190 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

over twenty metres high on the eastern side of the Red Sea. In Wadi
Hashubi he found the sand grains cemented by carbonate of lime, and
at the mouth of Wadi Nasb, are gravels cemented by calcite. Dr.
Raisin says there are low raised beaches on Perim Island in the Straits
of Bab-el-Mandeb.*

Without more definite information it is impossible to say whether or
not the beach deposits of the Red Sea are similar in nature and origin
to those of the coast of Brazil. Unfortunately a letter of inquiry, regard-
ing this matter, to the geologist in charge of the Egyptian survey
received no reply.

Leaving the Red Sea out of account, there still remains the question
why this hardening is not more general: why is it apparently confined
to the beaches of the Mediterranean Sea and of northeast Brazil?

RELATIONS OF Density TO DEPOSITION.

The salt water of the sea of a necessity cannot hold in solution as
much lime carbonate as can fresh water. This is due to the fact that
sea-water already holds so much mineral matter, most of which is more
soluble than the carbonate of line. It follows for the same reason that
the denser the sea-water the less carbonate of lime it will be able to
hold, or the more ready it will be to give up and deposit any that it
may have or receive in solution. We should, therefore, expect that
waters holding much carbonate of lime in solution, on flowing into the
sea, would deposit it more promptly in denser than in less dense sea-
water.

Jukes-Browne points out “that where a body of fresh water, containing
much carbonate of lime in solution, enters the sea, and remains exposed
to surface evaporation, a precipitation of carbonate of lime will take
place.” ?

There is a perceptible and probably constant variation in the density
of sea-water in spite of its movements and its commingling, and this
variation must influence the precipitation of lime in the beach deposits.
Furthermore, any increase of the density of the sea-water would hasten the
precipitation of the carbonates, and as it is precisely in the tropics and
in arid regions that the sea-water is densest, it is there that there is the
greatest tendency of the carbonates to be deposited upon the beaches.

1 Geol. Mag., March, 1902, IX., p. 182.
2 A. J. Jukes-Browne. The student’s handbook of physical geology, p. 213.
London, 1884.

BRANNER: THE STONE REEFS OF BRAZIL. 191

The accompanying map taken from the chart of the “Challenger” Re-
ports, Physics and Chemistry, Vol. I., shows the areas of densest sea-
waters over the globe. The variation in density must be due to the
different rates of evaporation. The almost closed basins of the Medi-
terranean and Red Seas are in warm, arid, or partially arid regions, where
evaporation goes on very rapidly. Some of the streams entering these

i

10270 4
VW. 2] 10265 ,
se a P0260) ce

zs a

10255 4
10250 »

Fig. 95. Surface densities of sea waters (“Challenger ’”’).

basins are heavily charged with lime, so much so that fresh-water tufa
deposits are forming at many places on a large seale. On entering the
sea the dense salt waters tend to hasten the deposition of the lime, and
this takes place most readily upon the beaches where evaporation is
most rapid.

The area of high sea-water density on the northeast coast of Brazil is
probably to be attributed to rapid evaporation on the surface of the

192 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

equatorial current that sets westward from the coast of Africa and
crosses the whole width of the Atlantic under a tropical sun. By the
time these waters reach the Brazilian coast, the density is greatly
increased by evaporation.

If the process on the Brazilian coast were the same as that in the
Mediterranean and Red Seas, the lime would be derived from the
streams. This may or may not be the case. Unfortunately I have no
analyses of the waters of the coast streams; but the geology of the
region leads to the conclusion that some of the streams are heavily
charged with lime, while others contain very little lime. The Creta-
ceous areas of Brazil are, or have been, largely limestone areas. From
the Abrolhos to Ceara sedimentary rocks cover most of the coast.

In the introductory geological sketch of the coast it has been pointed
out that where the sedimentary beds are unaltered, they contain con-
siderable lime, even when they are not limestones. It has also been
noted that the upper portions of these rocks along the whole length of
the coast where the stone reefs occur, have been profoundly weathered
and chemically altered. It seems probable, therefore, that during the
process of the alteration of these upper beds large quantities of lime
have been removed from the land and carried by the streams into the
already heavily charged sea-water.t It is a striking and significant fact
that the area of high density of the sea-water along the coast of Brazil
corresponds closely with the distribution of the stone reefs.

Whether the cementing material was brought down from the land or
was thrown upon the shores from the ocean, it seems that the unusual
amount of hardening of beach sands along the northeast coast of Brazil
is to be attributed indirectly to the density of the sea-waters in that
region.

IV. The seaward percolation of acid land-water.— The density of
the sea-water is, or may be, an element of controlling importance in the
hardening of the reef rocks. It is also evident that this density is
directly attributable to climatic conditions. But climatic conditions
affect the land and its streams even more than they do the ocean.

No analyses of the waters of the streams of northeast Brazil being avail-
able, it cannot be said whether or not those streams are heavily charged
with lime. But speaking from a general knowledge of those streams, I
should say that outside of the State of Sergipe their waters are not
so charged.

1 Murray shows that sea-water contains 2,000,000 tons of calcium to the cubic
mile. Nature, February 28, 1889, XXXIX., p. 426.

BRANNER: THE STONE REEFS OF BRAZIL. 193

It is not improbable, however, that the streams may be affected
* physically as well as chemically by climatic conditions.

Possible influence of climate. — In Chapter V., p. 143, it has been shown
that only the strong streams are able to enter the ocean boldly ; weaker
ones are compelled to seek outlets behind barriers, such as spits, reefs,
headlands, or other protection ; while the still weaker ones are often closed
altogether by the embankments of sand thrown across their mouths by
the ocean.

In so far as precipitation is concerned, the climatic conditions of north-
east Brazil are very variable. As arule, even in years of abundant rains,
the precipitation takes place in a few months, and the rest of the year is
very dry.1 For this reason the streams are spasmodic at best. But
there are from time to time drouths that last for years. During these
prolonged dry periods, all but the larger streams are completely dried
up, or are converted into a string of stagnant pools. Streams in such
a region must have their mouths closed during these long dry periods,
even though they may be abundantly able to keep them open in seasons
of heavy rains.

In all cases where the mouths of streams are closed, the waters are
held in pools behind the embankments, and obliged to escape to the sea
through the beach sands. Now the fresh-water pools thus shut out
from the sea are the homes of enormous quantities of aquatic plants, and
their margins are covered with a dense vegetation dropping its dead
leaves and fruits in the water. This organic matter, upon decomposition,
charges the water with organic acids. As the waters percolate seaward
through the sands of the beach, especially during low tide, when the
hydrostatic pressure of the water in the pools forces them forward, they
attack the calcareous matter with which they first come in contact, and
earry it along in solution until they encounter the sea-water. Here
there would be a tendency for the less soluble lime to be precipitated,
especially if there were a checking of the movement of the water.

Precipitation would thus take place along a beach-line, and would be
confined to a rather narrow belt, for its width would be something less than
that of the confining sand embankment, while its length would be deter-
mined by the coastwise length of the pools and of the restraining beaches.

The mouths of streams closed in this manner would in time be open
again, and there would be established a long slender reef of hard sand
rock with a break in it, through which the stream would discharge.

1 J. C. Branner. Decomposition of rocks in Brazil. Bull. Geol. Soc. Amer.,

1896, VIT., p. 809-312.
VoL. XLIVv. 13

194 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

Changes in the in-shore ocean currents, such as are constantly occurring,
would remove the consolidated sands from some parts of the reef and
heap them in other places.

Some of the conditions here hypothecated exist at present on the
southern coast of California. At and about Oceanside, San Diego
County, the region has been depressed and silts have filled up the stream
mouths and embayments. The streams are weak and spasmodic, and
unable to keep their mouths open, even when opened by floods. The
drainage waters collect in poolsand marshes behind the long sand beaches,
and escape by percolating through the beach sands. If these sands are
calcareous, we may expect in time to see them hardened and turned into
long lime-cemented sandstone reefs very like those of northeastern
Brazil.

This hypothesis appears to fit most of the conditions observed along
the stone reefs of Brazil: the streams and embayments across which the
reefs lie are streams and areas of weak drainage ; the reefs have the forms
and structure of beaches; unconsolidated sands underlie the hard reef
cap-rock.

At some places, however, the stone reefs rest against rocks through
and from which these lithifying waters could not have passed. At Cape
Santo Agostinho, for example, the northern end of the rock reef laps
back against granites for a long way north of the embayment behind the
Barra do Suépe. The percolation of acid waters from marshes and ponds
landward of the present reef might have hardened shore sands in front
of these marshes into a rock reef, but the sands that lay against the east
face of the cape had no pools to the landward. If they were hardened
by this process, the acid waters of the marshes must have saturated the
sands for considerable distance up and down the coast, as well as in
front of the marshes.

The hardening .process is not a continuous one. —If the process by
which the reef rocks are hardened were a continuous one, we might ex-
pect to find an overlapping series of sandstones filling the embayments.
This overlapping series does not exist. There are sometimes two or
three reefs, one behind the other, but even in these cases the reefs are
separated from each other by softer layers of sands. The sections of the
Pernambuco reef obtained by Sir John Hawkshaw also show that there
are loose sands interbedded with the hard layers. The undermining of
the reefs by the surf at many places along the coast shows that this
alternation of hard and soft beds is a characteristic feature of the large
stone reefs.

Ye a, ae

BRANNER: THE STONE REEFS OF BRAZIL. 195

We are, therefore, obliged to conclude that the process of hardening is
not perfectly continuous. This lack of continuity is not a time break,
properly speaking, but simply a break due to local physical and chemical
conditions.

That the beds of sand harden in some places and not in others is a
well-known fact, though just why it happens so is not always clear.
Nelson long ago called attention to the difference in the hardening of
the calcareous sands of Bermuda,’ and Dall notes the local hardening
of the ‘‘ coquina ” in Florida.?

It seems probable at least that the conditions of lithification are nicely
balanced, and that they are readily and frequently disturbed.

Some of these disturbances are due to geographic causes. When a
stream enters the sea, there is a tendency for it to be crowded to one side
by marine currents, especially during the low stages of the river water,
but during freshets the river often breaks through the barriers heaped
across its mouth by the sea, and establishes a new channel which it may
or may not be able to keep open. In any case, there is a tendency for
the stream behind the barrier to shift its channel, especially in the early
part of its history, and this shifts the site of the active consolidation of
beach sands. In the early development of the coast, the new beaches
formed to seaward of the older ones, and this process continued until the
cutting of the shores nearly ceased. Some of these newer beaches were
hardened, but many of them were not, according to the relation of the
beach to fresh-water bodies behind them.

There is, therefore, no more reason for expecting a continuous process
of hardening than for expecting all parts of a given bed to harden alike.
The hardening is probably now in process in favorable localities. I have
no doubt but that it is going on, for example, in the vicinity of Traigao
and the Lagéa de Sinimbu.

CONCLUSIONS REGARDING THE CONSOLIDATION OF THE REEFS.

Stone reefs are formed where there are streams or lakes of fresh water
entirely or partially restrained by the beach sands. The new reefs may
be formed either in front of the old ones, or in the embayment and
estuary behind the older ones. For similar reasons, stone reefs may
form behind or landward of the coral reefs. This can only happen,

1 Richard J. Nelson. On the geology of the Bermudas. Trans. Geol. Soc.,
London, ser. 2, V., p. 123. London, 1840.
2 Amer. Journ. Sci., ser. 3, XXXIV., p. 163.

196 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

however, in places where marine currents prevent the land-water from
interfering with the growth of coral reefs.

The local lithification of the sea beaches is not uncommon, but the
most noteworthy instances of lithification on a large scale are those of
the northeast coast of Brazil and of the Levant.

The cementing material of the Brazilian stone reefs is chiefly lime
carbonate.

The hardening of beach sands may be produced in the following
ways : —

1. By carbonated rain-water dissolving out the lime carbonate in the
upper portions of calcareous sands and depositing it in the lower portions.

2. By the escape of carbon dioxide from the sea-water when the surf
breaks upon the beaches.

3. By the escape of carbon dioxide from sea-water where it is warmed
by the tropical sun.

4. By the submarine escape of carbon dioxide about volcanic vents.

These processes may have contributed somewhat to the hardening of
the Brazilian reefs, but they do not seem competent to account for them
altogether. These theories are especially incapable of accounting for
the lithification of beaches behind older reefs.

The distribution of the consolidated beaches of northeast Brazil lead
to the inference that the consolidation is directly related to the density
of the sea-water. The geology and climatic conditions over the adjacent
land are, however, important factors in the hardening of the reef sands.
It seems probable that the consolidation of the reef sands would not
take place if the rainfall were large enough and constant enough to keep
the mouths of the streams open and the water of the streams fresh.

Tn a region of concentrated rainfall and long drouths the river mouths
become temporarily closed, and the abundant aquatic and other life in
the lagoons thus formed contributes to the organic acids of the waters,
which, upon penetrating the wall or dam of beach sand, first dissolves
the lime, and then redeposits it when it comes in contact with the dense
sea-water on the ocean side. In this manner some portions of the
beaches have been hardened, while others have remained incoherent.

The density of the ocean water is in all probability considerably
greater during the dry than during the rainy season, and this would
still further hasten the consolidation of the beaches during dry seasons.

The process of beach hardening is not a continuous one, but varies
with geographic and climatic conditions. New reefs may be formed
behind the older ones on the shores of the estuaries and embayments.

BRANNER: THE STONE REEFS OF BRAZIL. 197

Vit
The Age of the Sandstone Reefs.

Ir the conclusion reached from the study of the process of consoli-
dation is correct, we may reasonably suppose the formation of the stone
reefs has been going on, wherever the local conditions were favorable,
ever since the depression of the coast in early Pliocene times. The
principal facts that support this view are : —

Ist. The stratigraphic relations of the reef rocks to the other rocks
of the region.

2d. The relations of the reefs to the adjacent shores.

It is possible that the fossils in the reef rock, in connection with a
study of the living fauna of the coast, would bear out this theory, but
no study either of these fossils or of the coast fauna has ever been made.

Stratigraphic relations. — The rocks exposed along the coast on and
against which the stone reefs are built vary in age from Archaean to
recent.

At Bahia, the stone reef rocks abut against very old crystalline
schists and eruptives; at Cape Santo Agostinho they rest directly
against granites assumed to be of Archaean age. At many places water-
worn and subangular fragments of the iron-cemented sandstones, so
common in the weathered Cretaceous and Eocene Tertiary rocks,
are common in the reef rocks. Mention will be found of some of these
instances under the detailed descriptions of the reefs in Chapter IIT.

At Riacho Doce in the State of Alagéas, Tertiary (?) shales are
exposed upon the beach. These shales, and the granite boulders accom-
panying and underlying them in some places, have patches of coral
reefs lapping over them, and at two places on this beach I observed the
reef sandstone on top of the coral reef. One of these exposures is two
hundred metres long. At another place the sandstone reef lies directly
upon the Eocene rocks.

198 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

The stratigraphic relations of the reefs to the Tertiary beds are
matters of conjecture rather than observation. There are, to begin
with, but few places along the coast where both Pliocene beds and
sandstone reefs occur side by side. One of these is at Rio Formoso,
Estado de Pernambuco, where the stone reef is one and a half kilometres
from the Pliocene exposures on the Praia da Gamella.

At Serinhaem the Tertiary is exposed on the side of the river at the
town, and the reef does not touch them.

At Mamanguape the relations of the Tertiary sandstones and the
reefs appear to be as shown in Figure 8, page 29.

At Rio Formoso and Serinhaem the Tertiary is considerably higher
than the sandstone reef; at the Mamanguape locality, there seems to
be but little or no difference of level.

On the shore of the mainland opposite Catt on Itaparica Island,
Bahia, there is a long low sandstone bank that I take to be Pliocene.
There are no stone reefs near this, however.

At other places the relations of the stone reefs to rocks of known age
are not shown, but there are no facts in my possession that are not in
accord with the theory that the stone reefs are newer than any other
consolidated sedimentary beds along the Brazilian coast.

Physiographic relations. — The relation of the reefs to the adjacent
shores is accepted as evidence of the recent date of some of the reefs,
while the process of their formation strongly suggests, if it does not
prove, that the low, flat lands behind the stone reefs are underlain by
other stone reefs. Seashores are rarely at a standstill; they are either
being cut away or built out. Their elevation, as compared with that of
the land and their marginal position relative to the flat country behind
them, show that the reefs and the flat lands are genetically related, and
that they are of about the same age. These flat lands are partly recent
deposits ; but they also extend back into the Pliocene. Their origin
is discussed in Chapter V. One of the most striking features of the
external stone reefs is their proximity to and parallelism with the shores
behind them. If a stone reef had been in existence for a long time,
speaking geologically, it would have been either obliterated by the
encroaching sea, or it would have been buried under the encroaching
land.

The fossils in the reefs. — The fossils found in the reef rock, so far as
they are now known, are the remains of animals now living in the seas
along side of the reefs. At Pernambuco, Rio Formoso, and Mamanguape
the most common fossils are the shells of “mariscos” (a species of

BRANNER: THE STONE REEFS OF BRAZIL. 199

Venus) which are as fresh and bright as the shells upon the present
beach.! These bivalves are much sought for as food. They are taken
in the bays behind the reefs and near the shores, and also on sandbars.
Their dead shells are abundant on the present beaches.

The Venus, so abundant in these rocks, lives in the sand; but the
animals stand on end about five centimetres below the surface, and the
living shells are covered with horny epidermis. The shells found in
the rocks are always, so far as I have yet seen, without epidermis, the
valves are apart, and the shells usually have the convex side upward.
These facts show that the shells, as they occur in the rock, are not in
the places where the animals lived.

Several other shells, mostly gasteropods, are found in the rocks of the
stone reefs, but without exception they are forms that are often found
dead on the beach, or living in the shallow water near shore.

The littoral character of the shells found in the reef rock should not
be overlooked, for Liais thinks some of the reef beds were formed at sea
(““formé au milieu de la mer”), and that they have been displaced since
then.?

Baraio de Capanema speaks of seeing fragments of pottery imbedded
in the rock near the lighthouse at Bahia.®

Hartt thinks Pissis and Darwin “in all probability ” mistook the stone
reefs for Tertiary rocks.* | This seems to be an unwarranted assumption,
for in Pissis’s paper there is no specific mention of the reef rocks,® while
Darwin, in his paper on the Pernambuco reef, assigns to them a recent
date.

Although one gets the impression that the fossils of the stone reefs are
all recent, the fact should not be overlooked that these fossils have
never been systematically studied in connection with the existing fauna.
Moreover, the reefs one sees, and to which access is easiest, are all the
new outer reefs, and usually the latest ones formed, while the old reefs
are to the landward, and usually near the bases of the hills that formed
the old shore lines.

1 One sometimes hears the suggestion that the fresh colors of the reef fossils
is evidence of the recent age of the sandstone reefs. This may be true to some
extent, but these colors alone could not be accepted as evidence. We have rocks
of Jurassic age even, whose fossils still preserve their bright colors.

2 L’Espace Celeste, p. 545, 548.

8 Trabalhos da Commissio Scientifica de Exploragio. Rio de Janeiro, 1866.
Introduccao, I., p. CXX XVII.

~ £ Geol. and Phys. Geog., p. 269.
& Mem. Inst. France, 1842, X., p. 398.

200 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

CONCLUSIONS.

1. The fossils and existing coast fauna are as yet too little known to
throw much light on the question of the age or ages of the reefs.

2. The stone reefs are built against rocks of all ages from Archaean
to recent.

3. The only rocks with which they seem to be interbedded are Plio-
cene and recent.

4. It is therefore inferred that the formation of the stone reefs began
in early Pliocene times, and that it has gone on down to the present time.

BRANNER: THE STONE REEFS OF BRAZIL. 201

VALET.
Annotated Bibliography of the Stone Reefs of Brazil.

Angelo, F. Michael, and Carli, Denis de. A curious and exact account
of a voyage to Congo in the years 1666 and 1667. Pinkerton’s
collection of Voyages and Travels, London, 1814, Vol. XVI. 152.

The authors of this account touched at Pernambuco on their way to

Africa. In the first part of it Angelo speaks of ‘‘a wall... which cred-

ible people say is natural, running three hundred miles, one part of it

enclosing the harbour.”

Anonymous (?). Sommier Discours ouer den Staet vandee vier gecon-
questeerde Capitanias Parnambuco, Itamarica, Paraiba ende Rio
Grande inde Noorderdeelen van Brasil.

This paper is a separate from the “ Bijdr. en Meded. II.” The article
is said to be from the “ Archief van Hilten,” and is dated January 19,
1608.

Speaking of Pernambuco (p. 306) the author says: “This haven is
wonderfully situated, for it has a continuous stone wall just like a dike,
forty paces or more in width, and from the bar it extends for more than
a mile in front of Recife, and on the inside it makes the harbor big
enough to hold many ships.”

Anonymous. Nautical Magazine for July, 1861, p. 345-349, contains
an article quoted from the Moniteur de la Flotte.

It says the Pernambuco reef is made by “coral insects.” References
to schistosity, vertical dips, and parallelism of the reefs with the moun-
tain systems of Europe suggest that the article may have been written by
M. Liais.

Anonymous. Pacific Line Guide to South America, containing infor-
mation for travellers and shippers to ports on the east and west
coasts of South America. London, 1895. 8°, 151 pp.

202 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

On p. 31 it is stated that the harbor of Pernambuco “is formed by the
recife, a singular coral reef which borders the shore, more or less from
Bahia to Maranham, a distance of nearly a thousand miles.”

Auchincloss, W. S. Ninety days in the Tropics or Letters from Brazil.
Wilmington, Del., 1874, p. 21.
This writer says, “the natural harbor is formed by a coral reef running
parallel with the shore.”

Ball, John. Notes of a naturalist in South America. By John Ball,
London, 1887.

On page 351 this writer says that Pernambuco is “ separated from the
open roadstead by a coral reef several miles in length.” The author was
at Pernambuco on board a transatlantic steamer, but, so far as I can
learn, did not personally examine the reef.

Barlaeus, Caspar. Res Brasiliz imperante Lllustrismo D. I. Mauritio
Nassovie, etc. Principe, per C. Barleum. Accedit G. Pisonis
Tractatus de Aere, Aquis et Locis. Clivis.

(This work has also the following title by which it is commonly
known: Rerum per Octennium in Brasilia.) Editio secunda. Clivis,
1660. (The ‘“dedicatio” is dated April 20, 1647.) The first edition
of this work was published at Amsterdam in 1647; the present refer-
ences are to the second edition.

Piso’s description of the reefs is given on p. 584-585. On page 248 is
a plan of the city and reefs of Pernambuco, and a view of the town and
reef taken by the Dutch artist F. Post from the south, and looking
toward the city and the northern end of the reef. (Page 66): “ Between
Rio Biberibe and the ocean is a very narrow sandy tongue of land about
a mile (?) long.... Where it comes to an end is the so-called recife
(Reciffa) or receptacle (Receptus),’ probably so named because between
this tongue and another insular oblong tract called the stone reef ships
can enter.” (p. 248-249.)

It should be noted that Barlaeus was never in Brazil, and that his in-
formation was largely at second hand,? partly from Jean de Laet. The
work is important in this connection largely on account of the beautiful
drawings by Post.

Barrow, John. See Malte-Brun.

1 Barlaeus isin error here. Recife is the Portuguese word for reef, and the name
of the city was unquestionably taken from the reef, not from the form of the
harbor.

? Historia das lutas com os Hollandezes. Pelo Bardo do Porto Seguro, Lisbéa,
1872, p. 176.

BRANNER: THE STONE REEFS OF BRAZIL. 203

Bayern, Therese Prinzessin Von. Meine Reise in den Brasilianischen
Tropen, von Therese Prinzessin von Bayern (Th. von Bayer). Ber-
lin, 1897.

This writer passed through the Sao Roque channel in a small coasting
steamer, and mentions the reefs there, but does not say whether they are
stone or coral reefs (p. 204). She notes the interesting fact that at
Touros the palms have their trunks all leaning toward the northwest on
account of the predominating direction of the winds (p. 204). The
Natal reef is spoken of as a stone reef (p. 205). A photograph of the
Pernambuco reef is reproduced and the reef mentioned as being of sand-
stone (p. 213).

Belmar, A. de. Voyage aux Provinces Brésiliennes du Parad et des
Amazones en 1860, Londres, 1861, 42.
“Toute la céte est défendue par cette longue cordillere sous-marine
qui, de Santa Catherina jusqu’au Para, cotoie le littoral américain.” By
this sabmarine mountain chain is meant the stone reef at Pernambuco.

Bérenger. See Fournié.

Caminha, Pero Vaz de. Carta de Pero Vaz de Caminha published in
a foot-note in the Corografia Brazilica de Manuel Ayres de Cazal,
Rio de Janeiro, 1817, Vol. I. 12 to 34. It is also republished in
modern Portuguese in the Revista do Instituto Historico do Brazil,
1877, XL. pt. IL, p. 13-37.

This letter of Vaz de Caminha, one of the companions of Cabral, the
discoverer of Brazil, was dated at Porto Seguro, May 1, 1500. It gives
no specific information about the reef, but it contains the earliest record
of its existence, — that at Porto Seguro, — which he speaks of as “a reef
having a very good and secure port inside of it.” (p. 15.)

Capanema, Guilherme S. de. Trabalhos da Commissao Scientifica de
Exploragdo I., Introducgaio, Rio Janeiro, 1862, p. exxi-exxii.

This paper is the preliminary report of the geological section of the
commission. The author examined the reef rock near the lighthouse at
Bahia. He says: ‘There is a psammite there still in process of forma-
tion; the rock is sand cemented with lime, possibly derived from the
corals whose heads are destroyed as fast they emerge. This rock, which
is identical with that of the Peloponnesus and of the Antilles, is one more
proof of the elevation of our coast, for while it is of submarine origin, it
is broken above high-tide level. Instead of palaeontological documents,
it contains some that show the very recent date of the consolidation of
these sands ; I refer to bits of broken pottery.”

204 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

Of the Pernambuco reef he says that bits of lava have been thrown
upon the reef from which it has been stated that the reef is of igneous
origin ; this he says should deceive no one.

Cazal, Ayres de. Corografia Brazilica. Rio de Janeiro, 1817, II. 169

The author says the bay at Cururipe is protected by a reef, but
whether coral or stone, he does not say. The reef in front of Pernam-
buco, he says, extends from Bahia to Cape St. Roque (173) parallel with
and a short way from the shore; that it is at the level of high tide,
and six feet above low tide, perpendicular on the inside and sloping
outward.

Dapper, Dr. O. See Montanus, A.

Darwin, Charles. On a remarkable bar of sandstone off Pernambuco
on the coast of Brazil. The London, Edinburgh, and Dublin Philo-
sophical Magazine and Journal of Science. Oct., 1841, XIX., p. 257-
261.

This is the earliest geological description of the Pernambuco stone
reef. It contains a cut showing a cross-section of the reef. He says
that “it consists of a hard pale-colored sandstone, breaking with a very
smooth fracture and formed of siliceous grains cemented by calcareous
matter. Well-rounded quartz pebbles from the size of a bean, rarely to
that of an apple, are imbedded in it, together with a very few fragments
of shells.”

He thinks that its having withstood the action of waves so long is
“owing to the protection afforded by the thin coatings of Serpulae and
other organic beings.” He thinks that it is formed by the agency that
made the linear islands on some coasts, such as the Gulf of Mexico. It
is suggested that if the nucleus of a sand spit were once consolidated,
asmall change of level or of currents might cause the loose sand to be
washed away, leaving such a structure as the reef, which might be pre-
served from complete destruction by protection of animals.

Darwin, Charles. Journal of researches into the natural history and
geology. Voyage of the Beagle. New York, 1878, p. 198-199.

Mr. Darwin here remarks that he doubts “ whether in the whole world
any other natural structure has so artificial an appearance.” He ex-
presses the opinion that the reef was formed by the consolidation
(through percolation of calcareous matter) of a long spit or bar of Icsze
sand, and afterwards gradually upheaved. ‘The oldest pilots know of
no tradition of any change in its appearance.” This durability he at-
tributes to the coating of calcareous matter on its seaward face.

~

BRANNER: THE STONE REEFS OF BRAZIL. 20

o

Darwin, Charles. The structure and distribution of coral reefs. Sup-
plement on a remarkable bar of sandstone of Pernambuco on the
coast of Brazil. Third ed., London, 1889, p. 277-280. Second ed., p.
265-267.

This is a slightly modified reprint, without the cut, of the article
originally published in the London, Edinburgh, and Dublin Philosophi-

cal Magazine, Oct., 1841, p. 257-261.

Denis, Ferdinand. Brésil. Paris, 1863, p. 253.

Denis says that the reef extends from Bahia to Cape St. Roque, and
that at Pernambuco it is at the level of high tide and six feet above low
tide. He quotes the following from a manuscript of L. F. Tollenare :
“The rock composing it is a very hard sandstone which encloses a great
many perfectly preserved shells.”

Findlay, Alexander George. A sailing directory for the Ethiopic or
South Atlantic Ocean. 9th ed., London, 1883.

“The Recife, a singular ridge of coral rock which borders the coast,
has been previously noticed. It extends, more or less, all the way from
Point Toiro, or Calecanhar (lat. 5° 94’), to the Morro of St. Paulo (13°
23/), and its intervals form the entrances to the various ports” (p. 378).
The stone reefs are not distinguished by this author. After this general
description they are all spoken of as “reefs,” including the most not-
able of the stone reefs. He adds, however, regarding that at Pernam-
buco: “ Mr. Cowper, formerly H. M. Consul at Pernambuco, considers
that this reef is of coralline origin, and that when it has reached the sur-
face, the insects abandon their labour, and the interstices of their beau-
tiful fabric become choked with sand and broken shells, which after a
time become incorporated with it, and form in appearance what is

a rough sandstone” (p. 386).

Fletcher, J. C., and Kidder, D. P. Brazil and the Brazilians. 9th ed.
London, 1879, p. 513, 516. On page 516 is quoted the description
given by Dr. Kidder, which see.

On page 513 is given the same poor woodcut of the entrance to Per-

nambuco as that first published in Hadfield’s Brazil, p. 98.

Fournié, Victor, and Béringer, Emile. Mémoire sur le port du Recife.
Uitgegeven van wege het “ Aardrijkskundig Genootschap.” Bij-
blad, No. 8. Amsterdam and Utrecht, 1881.

-The second part of the mémoire by M. Béringer is upon “ Le port de

Pernambuco et la ville du Recife au 17e siecle,” and includes the infor-

206 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

mation the author was able to gather in Holland regarding the port,
reef, and city of Recife during the occupancy of the Dutch from 1630 to
1654. This paper is accompanied by an interesting map showing the
changes thus found to have taken place between the middle of the seven-
teenth century and 1876, when this map was made. It gives a brief
résumé of the physical history of Pernambuco during Dutch occupation.
“As an example of the rather strange topographic inexactness,” he cites,
‘the pronounced bend of the reef, . . . a bend which could not have
existed, as one may see, aside from other proofs, by glancing at the pan-
orama of the port drawn by Post in Barlaeus’ history.”

Francisco de Brito Freyre. Nova Lusitania, Historia da guerra Bra-
silica. Lisboa na officina de Joam Galram, Anno 1675. Livro
quarto, sec., 339, p. 176.

Speaking of the city of Recife, the author says: ‘‘ The impetus of the
waves is broken by the chain of a very remarkable reef which rises
slightly above and is occasionally covered by water, continuing a great
number of leagues, whicb, though cut by nature, is almost as even as ar-
tificial walls.”

Gama, Jozé Bernardo Fernandes. Memorias Historicas da Provincia
de Pernambuco. Pernambuco, 1844-8.
Volume III. contains a plan of the city and reef of Pernambuco, after
Barlaeus (1647). Volume IV. has another plan after Col. C. J. de Nei-
meyer on which the position of the reef is shown by a straight line.

Gandavo, Pero de Magalhanes de. Histoire dela Province de Sancta-
Cruz que nous nommons ordinairement Brésil. Lisbonne, 1576.
(Voyages, relations et mémoires originaux de L’Amerique. Par
Henri Ternaux. Paris, 1837. II.)

Speaking of the Pernambuco reef, this author says: ‘At one league to
the south of the Olinda colony, a reef or chain of rocks forms the port ”
(p. 37).

Gardner, George. Travels in the Interior of Brazil, principally through
the northern provinces. London, 1846, p. 80, 94, 103, 104, 154.

At Pau Amarello, a small fishing village between Pernambuco and
Itamarica, the reef is about a mile from the shore, and is thers not con-
cealed by high water. Gardner noticed a strong resemblance between
the reef rock and the sandstones at Rio Formoso, and thought he “could
trace, at low water, a rocky connection between the reef and the rocks of
which the hills were composed. It is more probable that the reef owes

BRANNER: THE STONE REEFS OF BRAZIL. 207

its origin to the decay of the rock between it and the shore.” He con-
sidered the rocks at Rio Formoso the same as the Cretaceous rocks of
Ceara, and he therefore must have considered the stone reefs to be
of Cretaceous age.

He notes a reef at Aracati (154), north of Cape St. Roque.

Affonso H. de Souza Gomes. Relatorio sobre 0 melhoramento do
porto do Natal, apresentado ao Ministro e Secretario dos Negocios
da Agricultura. . . . Natal, 1890. 10 pp. and maps.

This report says the Natal reef is of sandstone like that of Pernam-
buco, hardened, as Hartt explained, by lime derived from shells in the
beds. The rock opposite and inside the bar — Baixinha— he says is
the same as the rock of the reef. The author speaks of one single con-
tinuous reef along the coast, but he thinks the weakening and breaking
of it due to the river current. The map of Hawkshaw is reproduced on
a small scale.

The greater part of the paper is necessarily taken up with suggestions
regarding the improvement of the port.*

Graham, Maria. Journal of a voyage to Brazil. London, 1824.

Mrs. Graham visited Pernambuco in 1821, and examined the reefs.
She says (p. 101) that “the rock of which the reef is formed, is said to
be coral ; but it is so coated with barnacle and limpet above barnacle and
limpet that I can see nothing but the remainder of these shells for many
feet down, and as deep into the rock as our hammers will break... .
The reef is certainly one of the wonders of the world; it is scarcely
sixteen feet broad at top.”

According to Maria Graham (p. 101), the Pernambuco reef was arti-
ficially mended by Count Maurice during the time of the Dutch ocen-
pancy. The lighthouse was just being put up on the reef when she
went there in 1821.

Guelen, Aug. de. Briefve relation de l’estat de Phernambucq, dédié a
l Assemblée des Dix-neuf pour la tres noble compagnie d’West-Inde,
par A.de Guelen. Amsterdam, 1640. 4°, 22 ff. (Not seen; title
from A. L. Garraux’ Bib. Bras. Paris, 1898.)

Hadfield, William. Brazil, the River Plate, and the Falkland Islands.
London, 1854.

Speaking of Pernambuco, he says (p. 101): ‘‘The harbor is quite a
natural one, formed by a reef of coral rocks already described as running

1 For a copy of this rare report I am indebted to my friend, Dr. José de Ber-
redo, Engineer, Natal.

208 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

along the whole extent of the Brazilian coast, and supposed to be con-
tinued inland, where the coast projects beyond the line of the reef.”
The woodcut of the reef on p. 98 is quite worthless. Elsewhere he
says (p. 96) that the reef ‘‘extends along the whole coast of Brazil
from Cape St. Roque to the Abrolhos near Rio de Janeiro, and is of the
same hard coral nature.”

Hartt, Ch. Fred. Geology and physical geography of Brazil, Boston,
1870.

Professor Hartt notes (p. 62) the occurrence of a bit of consolidated
beach of “ quartz sand cemented by carbonate of lime,” just south of
Guarapary, Province of Espirito Santo. At Barra Secca, about 30 miles
north of the mouth of Rio Doce, he found similar consolidated sands un-
covered at low tide (p. 107). Again at As Pedras (Espirito Santo), he
found the same kind of sandstone on the sea beach (p. 114). “The
arrangement of the materials in this sandstone is precisely like that of
the beach, and this formation is only the lower part of a beach ridge
which has been cemented by the lime of shells, etc.” The rock is very
hard ; it is in places broken into blocks which lie tilted about. He
suggests (p. 115) the probability of the waters of lakes behind the beach
percolating through the sands, and that this might have been an agency
in its solidification.

He speaks of the stone reefs of Brazil in general (p. 185-187), shows
how coral and stone reefs have been confused on the Brazilian coast, and
how many erroneous statements have passed current regarding them.
The Porto Seguro reef is described, and a cross-section given (p. 228-229) ;
this reef is said to be remarkably straight, and its height and width even,
while it overhangs on the land side. The solidification is said to have
extended ‘many feet below low-water level;” in places it is coated on
the outside by corals; the lamination slopes seaward ; the rock is sand-
stone with calcareous cement. The stone reef at Santa Cruz is described
(p- 233), and a sketch map given showing its location. He speaks
(p. 342-344) of the consolidated beach sancs east of the lighthouse at
Bahia ; these sandstones dip seaward, and occur from Bom Fim to Rio
Vermelho. They contain fresh shells. The hardening is explained as
produced by the solution of carbonate of lime by rain and sea-water from
shells in the sands, and redeposition at a lower level. Copious rains, he
thinks, aid this work, also waters from marsh lands; later the loose
material is removed by storms or freshets. The Rio Vermelho reef is
described and is said to be somewhat elevated. The same section is

.
|

BRANNER: THE STONE REEFS OF BRAZIL. 209

given (p. 344) as that for Porto Seguro (p. 229). These rocks, he says,
are quarried for building purposes.

The Pernambuco reef is described (p. 4534) as the same as those of
Porto Seguro, Sta. Cruz, and Bahia, and a small map shows its general
location. He presumes that Barlaeus’s map of Rio Parahyba shows a
stone reef; the reef at Rio Grande do Norte is put down as stone (p. 455)
with a small map from Almeida.

Hartt, Ch. Fred. Relatorio preliminar de trabalhos da Commissao
Geologica na Provincia de Pernambuco. Rio de Janeiro, 1875.

Professor Hartt states (p. 4-5), in speaking of the stone reefs, that
his studies of them prove that the earlier theory advanced by him is
correct, and the idea that the Pernambuco reef extends north and south
for long distances is entirely wrong. ‘These reefs he considers local.
That south of Cape Sto. Agostinho is remarkably regular. Such reefs
are found in various stages of development; in some places there are
two or three of different ages, separate, but parallel. The later consoli-
dated beaches are thin and rest in loose beach sand.

Hartt, Ch. Fred. Algumas consideragdes sobre o recife de Pernambuco.
Pelo Professor Carlos Frederico Hartt, Chéfe, etc. Revista do
Instituto Polytechnico. Tomo V. parte 2, p. 21-26. Rio de
Janeiro, 1875.

This article is dated March, 1876. It contains the same facts as those
given in the Relatorio Preliminar cited in the preceding article.

Hawkshaw, SirJohn. Melhoramento dos portos do Brazil. Publicagao
official. Rio de Janeiro, 1875.

This report, in Portuguese and English, contains descriptions of all the
more important Brazilian ports, among them those of Pernambuco and
Rio Grande do Norte. At Pernambuco borings were made upon the
reef, the first and only ones ever made. These borings are of great import-
ance in understanding the geology of the reefs; they show (p. 15) the
hard sand rock to be three or four metres thick ; below this are layers of
sand, clay, shells, ete.

A rock reef is mentioned at Ceara (p. 91). Among the charts accom-
panying the report is one showing the reef at Rio Grande do Norte, and
one at Pernambuco ; the latter also gives the details of the borings on
the reef.

Hawkshaw, J. Clarke. Notes on the consolidated beach at Pernam-
buco. Quar. Journ. Geol. Soc. 1879, XXXV., p. 239-244.
VOL, XLIV. 14

210 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY.

Mr. Hawkshaw was an assistant of Sir John Hawkshaw, who had the
borings made through the stone reef at Pernambuco in 1874. His paper
gives the section disclosed by the boring upon the reef opposite the
marine arsenal. He raises the question whether the existence of a bed of
hard rock below the reef can be regarded as evidence of an older beach
consolidated when it was at the surface. He is of the opinion, however,
that the coast has recently risen. He says the cementing material is
carbonate of lime. He is of the opinion that these reefs have been
formed from long sand ridges with lagoons behind them; that ‘‘the
percolation of land-water charged with carbonic acid derived from the
decayed vegetable matter in these lagoons through the sand ridges will
account for the formation of the beach rock, the water taking up and
again depositing the carbonate of lime of the shells.” “The flood-level
of the lagoon will determine the level of the upper surface of the beach
rock; and that of the lower surface would be determined by the
cessation of the consolidating action at the level at which the sand was
saturated by sea-water.”

Henderson, James. A history of the [sic] Brazil; comprising its geog-
raphy, commerce, etc. London, 1821, p. 382.

In speaking of Pernambuco, it is stated that ‘‘A recife, or chain of
reefs, which extends itself from the entrance of Bahia to Cape St.
Roque . . . in no part appears so much like an operation of human
art as here. It is prolonged for the space of a league in a direct line
with and about two hundred yards from the beach, having the aspect of
a large flat wall, being always above the level of the sea, and at low
water six feet is discovered.” It is “perpendicular on the land side, and
gradually declining on the other.”

Hinchcliff, Thomas W. South American sketches; or a visit to Rio
de Janeiro [sic], the Organ Mountains, La Plata and the Parana.
London, 1863.

On p. 11, he calls Recife ‘‘a coral reef, which extends, with few inter-
ruptions, like a regular sea-wall, for nearly four hundred miles along the
coast of Brazil.”

Keller, Franz. The Amazon and Madeira Rivers. New York, 1874.

This writer, in speaking of Pernambuco, says that: “On the remark-
able coral reef that protects the port are a fine new lighthouse and a
quaint old watch-tower. . . . This coral reef . . . is extending all along
the coast of Brazil” (p. 26).

oe ie Aa

BRANNER: THE STONE REEFS OF BRAZIL. yy i |

Kidder, Daniel P. Sketches of residence and travel in Brazil. 2 vols,
Philadelphia, 1845. IT. 123.

Dr. Kidder states that the rock of the reef of dark brown external
appearance is hard yellowish sandstone containing bivalve shells; he
refers to its “ extending along the greater portion of the northern coast
of Brazil.” The top of that at Pernambuco, he says, “is scarcely visible
at high tide.” ‘ At low water it is left dry, and stands like an artificial
wall.”

Koster, Henry. Travels in Brazil. Ist ed. London, 1816. 2d ed.
London, 1817.

Koster lived in the Province of Pernambuco from 1809 to 1815. In
Vol. I. he gives a plan of the port of Pernambuco, showing the reef,
furnished “by an English gentleman resident at Recife.” It shows the
reef curving toward the land. “The reef of rocks . . . continues along
the whole coast between Pernambuco and Maranham, and in some parts
it runs at a very short distance from the shore, and in this case is usually
high, remaining uncovered at low water, as at Recife; but in other
places it recedes from the land and is then generally concealed. It has
numberless breaks in it, through which the communication with the sea
is laid open.” (p. 13-14 of 24 ed.)

Laet, Jean de. L’histoire du Nouveau Monde ou description des Indes
occidentales, contenant dix-huict Liures. Par le Sieur Iean de
Laet, d’Anuers. Leyde, 1640.

This writer, one of the directors of the West-India Company, lived in
Pernambuco from the arrival of the Dutch in 1630 until 1636.

Speaking of Olinda, he says (p. 530): “The port of this city . . . is
closed by rocks and banks as if by a bar (which borders the coast of
Brazil for many leagues) so that large ships enter only by a narrow
passage.” Again (p. 533), he says: “ Almost all the coast of Brazil is
bordered by rocks which form an almost continuous line, which rocks
are exposed at low tide, are about nine perches of ten feet wide and
often more and stand like a bar or rampart . . . cut at many points.”

Laet, Joannes de. Historie ofte Taerlijek Verhael vande Verrichtinghen
der Geoctroyeerde West-Indische Compagnie Zedert haer Begin tot
het eynde van’t jaer 1636. Leyden, 1644,
At p. 382 he gives a very good map of Cape St. Agostinho, showing
the stone reef south of there. A map is also given (p. 364) of the
mouth of the river at Rio Grande do Norte showing the stone reef.

212 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

Liais, Emm. L’espace céleste ou description de l’univers accompagnée
de récits de voyages entrepris pour en compléter l’étude. Paris.
2me edition. (1881.) (First edition, 1865.)

This work contains the only sketches published, so far as I can learn,
of the stone reefs immediately south of Cape Santo Agostinho (p. 545,
546). Of the stone reef in general it is said that it is higher than high
tide at but few points. It is a foliated sandstone of quartz and feldspar
with fragments of shells hardened by a silico-caleareous cement. He
notes that the reef is not one unbroken wall, but is made up of a number
of straight parallel lines, never curving. ‘‘The rock of the reef bears evi-
dence of displacement since its formation. Its beds dip seawards at an
angle of about forty degrees. At some places the dip is not so much,
but at others it is more marked, and south of the Serrambi point I have
even seen a part of the reef standing on edge.” He is of the opinion that
these sands were deposited in the sea in horizontal beds and subsequently
displaced by crust movement. He speaks of the protection of the ex-
terior by polyps. He evidently adheres to an earlier opinion about the
direction of the reef, for he says (p. 544), that “this question is...
connected with one of the most remarkable facts in the history of our
planet, namely, the alignment of the surface wrinkles upon the ares of a
great circle extending over immense distances.”

The Pernambuco reef is said to bear N. 20° E., and to be parallel to
the direction of the western Alps (p. 548). The reef rocks are considered
to be of later age than the hills of the coast (p. 547), and not far
removed from the modern epoch. He does not think the rock is now
forming (p. 548).

This writer was stationed at Olinda for eight months (1859-60) as
an astronomer of the Imperial Observatory, and his observations are
based upon personal <bservations (p. 279).

Liais, Emm. Inclinaison des couches de roches arenacées modernes
des cotes du Brésil; extrait d’une lettre a M. Blie de Beaumont.
Compt. Rend. 1860, L. 762-3.

This letter is dated Olinda, March 8, 1860. The author says, ‘“‘The

rock of the reef that borders the coast of America is a quartzose sand-

stone filled with shell fragments ;” that its structure is grossly schistoid,
and the beds inclined at an angle of 35° to 40°, with the strike N.
20° E.

The reef is made up of fragments of straight parallel lines, but not
always lying in the same prolongation, “ and as the coast is modelled on

sated

BRANNER: THE STONE REEFS OF BRAZIL. 213

the reef . . . its general direction oscillates a little about that of the
reef.” He refers to the eroded condition of the reef, and to the polyps
on its outside face, and says the quartz grains and shells are held
together by a siliceous lime cement.

The most remarkable point in this letter is that the author finds in
the direction of the reef confirmation of Elie de Beaumont’s theory of
the parallelism of structural features of the earth’s crust ; that the reef
follows these lines even more closely than the coast-line, and that it
agrees “with the direction of the Western Alps.”

Liais, Emmanuel. Climats, géologie, faune et géographie botanique du
Brésil. Paris, 1872, pp. 256-261.

The reefs are considered as proof of very recent elevations along the
Pernambuco coast (p. 256). ‘The reef rock is a sandstone composed
of quartzose grains and of fragments of shells hardened by a siliceous
calcareous cement, and presenting a schistoid structure.” Some of the
shell fragments he found petrified. The beds of rock dip seaward, he
says, at an angle of 35° to 40°. Near Serrambi, and south of there,
he says, he saw on the shore a part of the reef standing vertically. He
states that the reef is never crooked (‘‘ Jamais il ne se courbe”). The
surface decay is noted, and the protection given by polyps. He repeats
his earlier statement that the coast-line is ‘“ modelled on that of the
reef.” In age he thinks that the reef marks the close of the Quaternary
and shows the last elevation of the coast.

Lisbéa, Alfredo. Memoria descriptiva e justificativa do projecto do
melhoramento do porto do Recife... por Alfredo Lisbéa.. .
em 1887. Pernambuco, 1887.

This report has a very good map of the northern end of the reef.
The description of the Pernambuco reef is short but excellent. He ob-
serves that the reefs of the coast are not continuous; that they are
never higher than the highest tides; he gives the direction as S. 19°
32’ W. (true), with a length of three thousand one hundred and twenty
metres to the Barreta das Jangadas, and a width of twenty to sixty
metres. He notes the composition correctly, and thinks the sands hard-
ened by lime derived from the shells (p. 6-8). On p. 98-100, the
author quotes the opinion of Hartt in regard to the origin and nature of
the reefs of Brazil.

Malte-Brun, M. Universal geography, or a description of all parts of
the world. III. p. 389 and 401. Philadelphia, 1827.

214 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

Malte-Brun says the coast of Brazil “from Maranhao to Olinda is
bounded by a reef of coral, resembling in many places an artificial mole.”
He says also that the harbor of Porto Seguro “is sheltered on all sides
by steep coral rock.”

Malte-Brun. Voyage & la Cochinchine par les Tles de Madeére le Brésil
et I’Tle de Java (ete.). Par John Barrow ... Traduit de Anglais
avec notes et additions. Par Malte-Brun. 2 vols. Paris, 1807.

The fourth Chapter, from which the following is taken, was written by
Malte-Brun. Tome L., p. 156, says : ‘The northern coasts of Brazil from
Para to Olinda are bordered by a reef . . . which at many points re-
sembles an embankment or dike. It is without doubt of coral rock.
The inhabitants of Olinda and of Parahyba use it to build their houses.
Similar reefs form all the ports and estuaries of the province of Porto
Seguro ; they look like a natural wall along the coast.” The foot-notes

lead one to suppose that these observations are taken from the writings
of Piso and Barlaeus.

Mansfield, C. B. Paraguay, Brazil and the Plate. Letters written in
1852-1853. Cambridge, 1856, p. 27-29.

A small sketch is given showing the reef and harbor at Pernambuco.
“This reef, which seems to be about five or six feet across, runs along
the coast for some three hundred miles. . . . It is formed of sandstone,
full of pebbles and shells, and stands up just like a wall.”

Maximilian, Prince of Wied-Neuwied. ‘Travels in Brazil. London,
1820.

The author travelled (1815-1817) along the coast from Rio de Janeiro
to Bahia. Just south of the mouth of Rio do Frade (South of Porto
Seguro) he found (p. 259) “at very low water extensive banks of sand
and calcareous rocks, which stretch far into the sea, and which have
probably been chiefly produced by zodphytes. Their surface is divided
into regular parallel clefts.” (French ed. Paris, 1821. II., p.72.) He
mentions the reef at Porto Seguro (265), and another across the mouth
of Rio Santa Cruz, five leagues north of Porto Seguro (p. 268. French
ed., II., p. 87-88).

Montanus, Arnoldus. De Nieue en Onbekende Weereld of Beschrijving
van America en 7i Zuid Land, Vervaetende d’Oorsprong der Amer-
icaenen, etc. Door Arnoldus Montanus t’Amsterdam. By Jacob
Meurs, 1671.

The German translation of the above, erroneously credited to Dr. O.
D(apper), has been examined. It is entitled Die Unbekante Neue Welt,

a ke

BRANNER: THE STONE REEFS OF BRAZIL. 245

oder Beschreibung des Welt-teils Amerik und des Sud-Landes, etc. Durch
Dr. O. D. Zu Amsterdam. Bey Jacob von Meurs, 1673.

Mention is made of the reefs at many places along the coast. Oppo-
site page 542 is a copper-plate giving a view of the Pernambuco stone
reef from the south end. This plate is probably from the first edition
of Barleus, however, and the drawing was probably made by the Dutch
artist Francis Post between 1630 and 1654. A part of the same view,
somewhat modified, is reproduced in Varnhagen’s Historia Geral do
Brazil, 2d ed., I., p. 504.

Moreav, Pierre. Histoire des derniers trovbles dv Brésil entre les Hol-
landois et les Portvgais. Paris, 1651. (Description du recif.)

‘¢ Tt is to be observed that Brazil from one end to the other, said to be
a distance of a thousand and fifty leagues, is bordered its whole length
by a large long flat rock usually from ten to twenty paces wide, in the
sea and a gun shot, more or less, from the shore, as high as a pike or
more, uncovered when the tide is out but not otherwise because it is all
covered.” This work has a rather fantastic sketch, map, or diagram of
the reef and of the region between Olinda and Affogados (p. 3).

Mouchez, Ernest. Les cétes du Brésil, description et instructions nau-
tiques. Premiere section: du Cap Saint Roque a Bahia. Paris,
1874.

This author says (p. 15, also p. 23) of the coast between Cape St.
Roque and Rio Sao Francisco, that ‘a coral reef borders all the coast
from one to two miles out,” and that south of the Sao Francisco, “ the
reef ceases where sand dunes begin.” The reef is said (p. 23) not to
be higher than high tide, and that it “is sometimes of groups of corals
more or less distant from each other, as at Cape St. Roque, and at other
times it forms a veritable wall parallel with the shore, as at Pernambuco.”

Reefs are spoken of at many of the various points at which they are
known to occur, but no mention is made of stone reefs as such.

Nieuhof, Johan. Gedenkweerdige Brasiliaense Zee-en Lant-Reize. Am-
sterdam, 1682.

This author derives Pernambuco from Inferno en bokko, which he un-
derstands to mean the “mouth of hell,” on account of the rocks about
the harbor’s mouth (p. 13). Upon this explanation of the word Per-
nambuco, see foot-note under “ Rolt.” This is not properly rendered
in his English edition.

On page 15 he gives the description quoted under the next title.

216 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

Nieuhoff, John. Voyages and travels into Brazil, with a particular ac-
count of all the remarkable passages that happened during the
author’s stay of nine years in Brazil (first half of the seventeenth
century). Vol. XIV. (p. 697-881) of Pinkerton’s collection of
Voyages and Travels. London, 1813.

The Pernambuco reef is described on pages 708-709. He says that
“the whole coast of Brazil is, from one end to the other, surrounded
with a long, thick, and fiat ridge of rocks, which in some places is twenty
and in other thirty paces broad ; however, there are certain passages in
this ridge through which the ships approach the shore and some few
places, where this ridge is not to be found at all.” He says that “at
low tide most of those rocks appear above water; though the tide never
fails to cover the same.” He generally speaks of the reef as the “stony
reef.”

For the original edition of Nieuhof’s book, see the preceding title.

Nieuhoff, John. Voyages and travels into Brazil and the East-Indies:
containing an exact description of the Dutch Brasil... with a
most particular account of all the remarkable passages that happened
during the author’s stay of nine years in Brasil (1640-1649). Trans-
lated from the Dutch original. London, printed for Awnsham and
John Churchill at the Black Swan in Pater Noster Row, 1703, 4°, ill.

The author, who was very familiar with the northeast coast of Brazil,
states (p. 9) that “the whole coast of Brasil is from one end to the
other, surrounded with a long, thick and flat ridge of Rocks, which in
some places is 20 and in others 30 Paces broad: However there are
certain Passages in this Ridge through which the Ships approach the

Shoar, and some few Places, where this Ridge is not found at all.” He

ulso states that at “‘ Low-Tide most of those Rocks appear above Water ;

though the Tide never fails to cover the same.” Of the reef at Pernam-
buco he says: ‘It is very flat, without any Prominences.”

Olfers, J.F.M.v. Ueber das niedrige Felsenriff der Kiiste von Brasilien.
Archiy fiir Mineralogie, Geognosie, Bergbau und Hiittenkunde.
Herausgegeben von Dr. C. J. B. Karsten. IV., p. 173-183.
Berlin, 1832.

This is the earliest paper written by a geologist, and is one of the
most important upon the stone reefs of Brazil. The author distinguishes
between the stone and the coral reefs, and describes the rock of the stone
reefs so that there can be no misapprehension regarding their character.
He expresses the opinion that these reef rocks are of Tertiary age, but he

BRANNER: THE STONE REEFS OF BRAZIL. yA

confuses them with the Tertiary rocks of the Bahia basin, with the sand-
stones along the Amazonas, and with the rocks forming reefs of both
Cretaceous and Tertiary ages along the coast from Abrolhos to Maranhao.
He appears to regard the reefs as narrow remnants of the Tertiary beds
along the east coast of Brazil.

M. A. Vital de Oliveira. Roteiro da costa do Brasil do Rio Mossoré
ao Rio de 8. Francisco do Norte. Rio de Janeiro, 1864.

This work, as the title indicates, is intended for navigators, but it
mentions several of the reefs of the coast. One is reported at Murihi,
one at Guagandu and one at Ceara-Merim. That at Natal is said to be
uncovered at low tide, and to end at the Ponta do Morcego, a little more
than half a league north of Pinto (p. 71-73). Mention is made of the
reefs at “ Pontal da Susana,” Cunhat, Traigfio, Mamanguape, etc. No
distinction, however, is made between the different kinds of reefs.

Penn, James. The South American Pilot. Part I. East coast of South
America, from Cape St. Roque to Cape Virgins. 4th ed. London,
1893.

In speaking of the reefs of the northeast coast of Brazil in general this
writer says (p. 48): “The Recife, a singular ridge of coral rock, borders
the coast generally at the distance of one-half to three miles, but in some
parts much farther off, and extends more or less from the northeast
point of Brazil, as far as Bahia; traces of it may be found more to the
southward, and also along the north coast to Maranham. The reef,
which is about 16 feet in breadth at the top, slopes off to seaward... . ”
In other parts of this work, no distinction is made between the stone and
the coral reefs, and the assumption seems to be that they are all coral,
though several of the most important stone reefs are mentioned, such as
those at Rio Grande do Norte, Traigéo, Mamangudpe, Cunhahu, Pernam-
. buco, and Santo Agostinho.

Antonio Bernadino Pereira do Lago. Memoria sobre a forte do mar
em Pernambuco. Published in the Revista do Instituto Historico
e Geographico do Brazil, 1862, p. 589-596.

This article is without date; it was written after 1814, however.
The author says the reef (a bank of rock) extends from S. lat. 6° to 18° ;
that is, from Rio Grande do Norte to the Abrolhos almost parallel
with the coast, in some places uncovered, in others concealed, here
nearer the land and there further from it, and containing breaks or
passages,

218 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

Filippe Francisco Pereira. Roteiro da costa do Norte do Brazil. Per-

~nambuco, 1877.

This work, written for the use of coast pilots and sailing masters,
speaks incidentally of many of the reefs of northern Brazil. Opposite
page 36 isa map of the Barra de Goianna, Pernambuco, showing the posi-
tion of a reef somewhat broken and curved.

He says (p. 43) there are reefs about the mouth of Rio Guaja, on
the line between Parahyba and Rio Grande do Norte. The Barra do
Cunhahi, Rio Grande do Norte, is also circled by reefs lying near the
shore (p. 45). Others are mentioned (p. 50) at the mouth of Rio
Cearé-Merim. Off Cape St. Roque he says the reefs are about 6 miles
out and parallel with the coast, and extend 27 miles N.N.W. to Olhos
d@Agua. These last are probably coral reefs, however.

Piso, Gulielmus. De Indie Utriusque Re Naturali et Medica. Am-
sterdam, 1658.

Piso lived at Pernambuco during the Dutch occupancy under Maurice
of Nassau, 1637-1644.

Speaking of Pernambuco, this author says that the tide “strikes with
great violence against a reef or bank called by the Portuguese Reczfo.
All who have seen this reef are obliged to confess that it was placed
there by a great kindness of nature. The ledge of rock, extending a
long distance, opposes itself like a wall to the violence of the surf and
mad elements, and gives ships safe stations and ports. It also supplies
most abundant materials for buildings, and for the churches and monas-
teries which are the pride of Olinda and Parahyba. This same reef,
sometimes broken and crooked, again continuous and straight, protects
the greatest part of Brazil. (Maximam Brasilie partem eadem nune
interrupto § jflexuoso, nune continuato rectoque dictu tuetur.) Its breadth
"(it is very flat, and as smooth as if artificially polished) is twenty, some-
times thirty pacesand more. Its height is such that it is rarely covered
by the highest tide” (p. 6-7).

I have given this quotation at length, partly because it has been sup-
posed that Piso is the original authority for the occasional statement
that the reefs of Brazil are continuous.

The same description is quoted on pages 584-585 of Caspar Bidance s
Rerum per Octennium in Brasilia. 2d ed. Clivis, 1660,

' In Piso’s Medicina Brasiliense, published in 1648 (pp. 3-4), the same
account is given of the reef.

—=—=-

BRANNER: THE STONE REEFS OF BRAZIL. 219

Porto Seguro, Visconde de. (Francisco Adolpho de Varnhagem.)
Historia geral do Brazil, antes de sua separacio e independencia de
Portugal. 2a edig&o. Rio de Janeiro, n.d. Vol. I.

This work has a steel engraving (facing p. 352) showing the northern
end of the reef at Pernambuco in 1630. Another (op. p- 504) has a
view upon the reef looking north from near its southern end. (This
picture is reduced and changed from one given in “ Die Unbekante Neue
Welt” of Arnoldus Montanus, p. 542, credited to Dr. O. D. (see Mon-
tanus above) and made during the Dutch occupancy, probably by Post.)
Another plate (op. p. 530) gives a plan of the reef south of Cape Santo
Agostinho, made in 1636. The map of the same reef given herewith,
and made in 1899, shows that there has been no perceptible change in
that great reef since 1636.

Porto Seguro, Visconde de. Nota acerca de como nao foi na Corda
Vermelha na Enseada de Santa Cruz que Cabral primeiro desem-
barcou. . . . Acompanhada do texto integro da carta-chronica . . .
de Pero Vaz de Caminha. Revista do Instituto Historico do Brazil,
EST, ola, pts LI... p..5—37:

“Rio Buranhem, before entering the ocean at about lat. 16° 25'S.
meets a reef which runs parallel to the coast, nearly north-south, like that
at Pernambuco. . . . This reef is well above low tide, in some places it
has mangue bushes on it and in others sandy beaches ” (p. 5).

Purchas. Purchas his pilgrimes, in five bookes. London, 1625. Vol.
IV. Chap. 7, § 5, p. 1238.

“This place (‘Arecias’) is a league from Fernambuquo, being the
harbour where all the Shipping that goes from Fernambuquo doe arriue ;
from this place to the Cape you shall see the Clifts as it were a wall made
by Bricklayers, no higher in one place than in another, but all euen.”

It is also stated that these “ clifts,” that is, the reefs, “lye along the
coast as farre as the Riuer Saint Francis.”

Rathbun, Richard. A list of the Brazilian echinoderms, with notes on
their distribution, ete. Transactions of the Connecticut Academy
of Arts and Sciences, 1879, V., p. 139-158.
The echinoderms listed in this paper are partly from the stone reefs
of Rio Formoso and Pernambuco.

Rathbun, Richard. Brazilian corals and coral reefs. American Natu-
ralist, 1879, XIII., p. 539-551.

In this article Mr. Rathbun remarks that the stone and coral reefs of

Brazil are nearly coexistive, “but while the stone reefs are always con-

220 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

fined to the immediate neighborhood of the shore, coral reefs frequently
lie some distance out, at times forty or fifty miles.”

Rathbun, Richard. Notes on the coral reefs of the island of Itaparica,
Bahia, and of Parahyba do Norte. Proc. Boston Soc. Nat. Hist.,
1878, XX., p. 39-41.

Notes on the characters of the coral reefs at the places mentioned.

Rathbun, Richard. Prof. Hartt on the Brazilian sandstone reefs.
American Naturalist, June, 1879, XIIL, p. 347-358. The author
states that the paper “is partly in the very words of Prof. Hartt,”
but it is not always clear which parts Hartt is responsible for, or
which are to be credited to Mr. Rathbun.

In any case this article is the most important one ever published upon
the stone reefs of Brazil. It includes Hartt’s own work done previously,
and also most of the results of the work by the Commissiao Geologica do
Brazil on the reefs at Pernambuco, Porto Santo, Bahia, and Porto
Seguro. In regard to the height of the reef at Pernambuco it is stated
that it is about the same as high tide, “though on account of the great
commotion made by the waves at such times, it is impossible to exactly
determine this fact. . . . It is very evident that they [the reef rocks] are
not the outcropping edges of beds of sandstone . . . but only narrow
strips of stone of slight thickness formed in exactly the same position in
which we see them to-day, that is, just below the level of high tide.”
This solidification is considered to be due to lime carried into the beach
materials by percolating waters, both sea-water and rain, and by the
“encroachment of the sea aided by rivers flowing behind them these
consolidated beaches have often been separated from the main shore as
distinct reefs ; but sometimes this latter action has not taken place, and
the hardened layer retains its normal position upon the beach.” The
dip of the beds is attributed to the false bedding of the beach sand as
deposited and not to the upheaval of the coast. Of the Porto Santo
reef on Itaparica at Bahia it is said that there must have been an eleva-
tion to raise the reef at that place so high above water.

Rathbun, Richard. A praia consolidada e sublivada e os sambaquis de
Porto Santo. Archivos do Museu Nacional do Rio de Janeiro.
1878, III., p. 172-174.

Mr. Rathbun describes a stone reef at Porto Santo on the northeast
corner of the island of Itaparica, which lies within the Bay of Bahia and
northwest from thet city.

BRANNER: THE STONE REEFS OF BRAZIL. 221

He thinks it probably belongs to the same series of formations as the
sand reef of Pernambuco, and “is the only example known of the eleva-
tion of such materials.’”’ This bank is three hundred metres long and
rises four metres above the shore, falling away gradually both north and
south. The lower three metres of this beach are consolidated, and on this
rests a black sandy soil filled with shellfish and containing human re-
mains. The bottom half of the beach is of corals and water-worn shells
mixed with sand and small pebbles. In places it has enough lime in it
to allow of its being burnt for lime. ‘‘ This part of the beach resembles
in structure and hardness the consolidated beaches east of the Bahia
lighthouse. The hardening seems to have gone on more rapidly at
some levels than at. others.” He regards the Porto Santo deposit as
very superficial and recent; the shells and corals in it are all recent.

Reclus, Elisée. Nouvelle géographie universelle. La Terre et les
hommes. Tom. XIX. Amérique du sud: lAmazonie et la Plata
etc. Paris, 1894, p. 222-223; 244.

He says there is a line of reefs extending from the mouth of the Par-
ahyba to that of Rio Sao Francisco, some of them of coral and others,
like that of Pernambuco, of a different origin. “There is probably not
in the world a formation that has more the appearance of having been
built by the hand of man.” It is stated to have a width of from thirty
to sixty metres, to be flat on top, and uncovered at low tide. The rock
is said to be of a compact sandstone “in which it is difficult to distin-
guish the bedding.” He thinks the material was probably a line of
dunes, hardened by time.

He states that Agassiz thought the reef was a terminal moraine, but
makes no reference to the publication of this opinion.

Opposite p. 480 is a fine wood engraving of the Pernambuco reef, the
view being taken from the lighthouse at its northern end ; and on p. 245
is a map of Pernambuco showing part of the reef.

Rolt. A new and accurate history of South: America. ... By Mr.
Rolt. London, 1756, p. 546.

““The port of Arracife, opposite the town of Pernambuco, is so called
from its situation among a ridge of rocks, or sands ; and the harbor of
Pernambuco, or rather Infernoboco, the mouth of hell, was so named by
the Portuguese, on account of the rocks and shoals, under water, at its
entrance.” A similar explanation of “ Pernambuck” is offered by
Arnoldus Montanus in his Unbekante Neue Welt, p. 434. It should be
noted that this explanation of the word Pernambuco is not correct.

222 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY.

The original Tupi name appears to have been Parand-buc, meaning the sea
breaks, referring to the surf breaking on the reef. See O Tupi na geo-
graphia nacional. Por 'Theodoro Sampaio, p. 52 and 146. S. Paulo, 1901.

Roussin, Le Baron. Le pilote du Brésil, ou description des cétes de
VAmérique Meéridionale. Paris, 1827.

Speaking of the coast between Sta. Catherina and Maranhao (p. 34),
Roussin says it is skirted its whole length, except at certain intervals,
by two lines of shoals (enveloppée de deux ceintures de hauts-fonds).
The inner one of these fringes the shore with its rocks, especially from
Cape Frio to Maranhao, ‘‘ often at sea level, sometimes rising above it
from one to ten feet, more commonly submerged.” He states that by
breaks in this reef almost all the ports of the coast are formed. A
partial list of those believed to be so formed is given (p. 34). The
theory advanced by this writer to explain the reefs is that they are due
“in part to the heavy surf.” He conceived that the waves charged
with the debris of the shore were thrown back upon themselves (p. 35) ;
“but this movement of repulsion cannot fail to be counteracted by the
contrary pressure of the ocean mass; and there must result a sort of
stagnation of the waters at a certain distance from the coast and the
materials brought away must. be deposited at this point of repose.” He
adds in a footnote that this explanation does not apply to the uncovered
rocks, but to the shoals connecting them.

He mentions several of the stone reefs of the coast, but gives no
specific information except such as might be useful to sailing masters.

Saint-Adolphe, J. C. R. Milliet de. Diccionario geographico historico
e descriptivo do Imperio do Brazil. . . . Por J. C. R. Milliet de Saint-
Adolphe e transladada, . . . pelo Dr. Caetano Lopes de Moura.
Tomo II. Paris, 1845, p. 292.

“‘ All of Brazil, like the province” (of Pernambuco), “is protected from
the waves of the sea by a natural wall of reefs broken here and there to
give passage to the streams, from the city of Bahia to the ponta de
Touros in the province of Rio Grande do Norte.” This writer mentions
several reefs in front of certain ports along the coast, but there is
nothing to show the nature of them.

Serres, Marcel de. Sur les coquilles pétrifiees des environs de Bahia.
Compt. Rend. 1854, XX XVII., p. 362-363.

A short note referring to the views of Spix and Martius upon the
Bahia reef sandstone. He thinks that those authors overlooked the
fact that the shells in the Bahia rocks show that their petrifaction has
taken place in our own day.

BRANNER: THE STONE REEFS OF BRAZIL. ZL

Serres, Marcel de. Note sur la pétrification des coquilles dans
Yocéan actual. Compt. Rend. 1853, XXXVI., p. 14-16.

The author gives the results of the observations of M. Christine, a
surgeon in the French navy, at Bahia. He speaks of the recent sand-
stones near the lighthouse and north of it. He says they are very hard,
are used for building in Bahia, that they contain many shells, and also
petrified shells, living species, without traces of animal matter, but with
colors fresh. He is of the opinion that these examples show that shell-
bearing sandstones are in process of formation in the present seas, and
still more extensively in the oceans; that petrification goes on at
present ; ‘‘that the shell-bearing sandstones of Bahia must have been
deposited after the petrification of the shells which they enclose.”

Serres, Marcel de. Sur le dépéts récents des cétes du Brésil. Compt.
Rend. 1860, L., p. 907.

This brief paper (a letter to Elie de Beaumont) was called forth by
the letter of M. Liais upon the Pernambuco reef. M. Serres finds in
that letter fresh evidence in support of petrification going on at the
present time.

Smith, H.H. Brazil, the Amazons and the coast. New York, 1879,
p. 438-439.

“The reef looks much like an artificial breakwater from end to end,
it forms almost a straight line, and the height is very uniform — about
ten or twelve feet above high water.” On p. 439 there is a wood en-
graving of the reef made from a photograph taken from the lighthouse
at its north end. :

Santa Teresa, Gio: Gioseppe di. Istoria delle guerre del regno del
Brasile accadute tra la corona di Portogallo e la republica di Olanda.
Roma, 1698.

In Part II., at pp. 202-203, are a view and a plan of Pernambuco,
both exhibiting the reef. The plan is obviously inaccurate so far as
the city of Recife is concerned, and the reef is represented as strongly
curved. It is stated that (Part I. p. 21): “The Port of Recife is one
of the most frequented of the world; it is protected by a wonderful
mole formed there by nature, which rises above the water, and extend-
ing a great number of leagues, cut by nature with such regularity as if
they were so many moles made artificially at great expense.”

Souza, Pero Lopes de. Diario da Navegacio da Armada que foi a
Terra do Brazil em 1530 sob a Capitania— mor de Martim Affonso

bo
i)

24 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

de Souza. LEscripto por seu Irmao Pero Lopes de Souza. Lisbéa,
1839.
This writer was at Pernambuco in 1530, and makes mention of the
reefs at that place, at Cabo Sto., Agostinho, and at Sao Miguel (p.
14-15). He gives no descriptions of them, however.

Souza, Gabriel Soares de. Tratado descriptivo do Brazil em 1587.
(Published anonymously at Lisbon in 1825.) Revista do Instituto
Historica e geographico do Brazul, 1851, XIV.

This is probably the oldest account we have of the Brazilian reets.
They are not described in much detail, however, and no distinction is
made between stone and coral reefs. The author mentions (p. 25) reefs
near Goaripari just south of Cape St. Roque. The port of Rio Grande,
he says, has a reef like that at Pernambuco; reefs are mentioned at
Aratipicaba (p. 26); others from Rio Magoape to Itamaraca (p.
27, 31). The Pernambuco reef is said to be two leagues long (p. 33) ;
that at Rio Formoso is mentioned, also those at Rio Camaragipe, at
Porto Novo, and at Curruripe (p. 37). ‘There is said to be a reef at the
mouth of Vasabarris, at Braz Affonso, at Rio Joanne, Rio Vermelho, and
at Porto Seguro. He tells of the use (p. 354) of the reef rocks at
Bahia for building the city, and says these rocks were covered at high
tide ; that “the rock is white and hard, and does not go to pieces, but
is hard to work because it wears the tools. Fine and beautiful works
and very large grave stones are made of it. To one examining it, it
seems that this stone is made of sand hardened, for along these same
reefs and close to them the rocks are all black, while the former is very
white after it is cut. It is not very soft though, and when worked it
shows a sandy grain, and often oyster and other shells are found inside
the rock, and small pebbles. From this it is held that this rock is
formed from sand, and that it has been hardened by the coldness of
the sea-water, which is easy to believe, for there are found about these
shores mud filled with sand and congealed and hard as rock, and some
tree trunks also covered with this mass as hard as if they were of
stone.”

Spix, J. B. von, and C. F. P. von Martius. Reise in Brasilien. Miin-
chen, 1828, Vol. II., p. 795, 799.

On p. 795 it is said that “the harbor of Recife is formed by the rock
reef which gave name to the place, and extends along and parallel to the
coast in front of the town.” On page 799 they have a brief note upon
the coral reefs along the coast of Ceara.

BRANNER: THE STONE REEFS OF BRAZIL. 225

Varnhagem. See Porto Seguro, Visconde de.

Wappeus, J. EH. A geographia physica do Brazil. (Edigaéo condensada.)
Rio de Janeiro, 1884, p. 17-18.

From Cape St. Roque to Olinda, and even to Bahia, there is a narrow
bank of coral which begins to appear at Ceara. In places this connects
with the shore, at others it is three hundred to four hundred metres
away or even still further. At some places the reef is broken, forming
passages for vessels and even harbors, as at Pernambuco and Rio Grande
do Norte.

REsuME OF THE BIBLIOGRAPHY.

The following facts stand out prominently in this bibliography :—

I. Nearly all the descriptions of the Brazilian stone reefs hitherto
published relate to the one at Pernambuco, due no doubt to the fact
that Pernambuco is the most important port of Brazil north of Bahia.

II. The most valuable papers are those of Darwin, Hartt, Rathbun,
Hawkshaw, Fournié, and Beéringer.

III. Except in so far as they show that there has been no important
changes in the reefs within historic times other writings have but little
or no geologic value.

No attempt has been made to get together the old maps showing the
reefs of this coast, for with very few exceptions these reefs are put down
in a more or less conventional manner, without attempting to show their
real forms or extent. The earliest of these maps are probably those
made under Admiral Lichthart during the Dutch occupancy (1637-
44). The original atlas of these beautiful charts is in possession of
the Instituto Archeologico e Geographico Pernambucano, where the writer
had the pleasure of examining and copying them. The same institution
has several other maps of Pernambuco of even earlier date. The value
of all these maps, however, is historical rather than scientific.

VOL. XLIV. 15

226 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

IX.
The Coral Reefs.

PAGE Paan

Ieocal.details™ 7a aaa een Between Itaparica and Cara-
‘the Rocash =. s Apert Sate AS vellas:.°- 2: eee sg
Cape St. Roque “ase OF oem nay ee Off Caravelias: see col
Lavandeira reefs ... . . 228 Abrolhos reefs . . 256

Joao daiCunliaie. (a0 seen eco Thickness of the coal meee of
Ceard reefs . . aes iry we ee. Brazil; <a i e209
Fernando de Noronha Ae pais 9) The age of the coral a pire SAH |

Parahyba do Norte. 232 Chemical composition of Bra-
Between Parahyba and Recife 235 zilian Corals aera tes 268

Pernambuco to Santo Aleixo . 256 List of corals of the coast of
Santo Aleixo. . . 237 Brazil sce ee 200

Between Santo lees and Notes on corals collected. By
Maceio . . 5 oo 2B AWW Greeley: Beeainees ae 200
Analysis of reef oie ee oe ee 7! The Maceio coral reef . . 270

ThesBahia reeles cae .ce ie eeeO Conclusions regarding the cova
reefs |; 3 RA pore tee eee 14

WHEN the work on the stone reefs was begun it was not intended to
include with it anything upon the coral reefs. It was only after the
work was nearing completion that it seemed advisable to utilize the notes
made on the corals, and to use the geological history of the stone reefs
as far as possible to throw light upon that of the coral reefs. For this
reason these notes are fragmentary. I have endeavored, however, to
bring together what others have written upon the coral reefs in order to
make the paper as nearly a complete account of the coral reefs of Brazil
as can be written with our present information.

The accompanying map shows the distribution of the coral reefs so far
as it is known (Plate 1) at present.

Loca DETAILs.

The Rocas. —In 1852 the Rocas was visited and was first mapped
and described as a coral island.t This island is eighty-four miles due
west of the Peak of Fernando de Noronha, and one hundred and forty-
four miles from the Brazilian mainland. Its centre is in south latitude

1 Report and charts of the cruise of the U.S. Brig “Dolphin”’ made under the
direction of the Navy Department, by Lieutenant S. P. Lee. U.S. Navy, Wash-
ington, 1854 (83d Cong., Ex. doc. 59, p. 81-85).

BRANNER: THE STONE REEFS OF BRAZIL. 227

8° 51’ 27"; longitude 33° 48’ 57” west of Greenwich. “The reef ex-
tends about one and one-fourth miles in latitude and nearly one and
three-fourths miles in longitude and is covered at high water with the
exception of Sand and Grass islands on the west and the scattered rocks
on the south and east sides. These objects are from ten to fifteen feet
above the reef, which is formed of coral, generally level, though with
many holes in it. . . . We found coral bottom at fifteen fathoms, six
miles east of the reef, but no bottom at thirty fathoms, two and one-half
miles north-northeast, nor at seventy fathoms four miles southwest of it.
The tide rises about five feet.” (See page 82 of that work.)

Certain points are marked on Lieutenant Lee’s chart as black rocks
amid the coral reefs, suggesting that the reef may rest upon a base of
eruptive rocks. Findlay? has the following: “The Rocas. This low
coral reef is perhaps the most formidable danger in the Atlantic. It is
the only one of its character in that ocean —a true atoll isolated from
all the surrounding lands, so many of which are found in the Pacific.”

This author quotes as follows from a report of a visit by Commander
Parish made in 1856. He “obtained coral bottom in thirteen fathoms,”
before the island was sighted, and again he “anchored in twenty
fathoms,” before the island was sighted, and again he ‘anchored in
twenty fathoms, coral bottom, at about two and one-half miles from
the shore.”

In 1857, Captain J. H. Selwyn, R. N., resurveyed the Rocas and
wrote of it then: “ It is a perfect coral island, circular, about two
miles in diameter, and has in its centre a shallow lake with an opening
to the sea. The greater part of the reef is under water. There are two
sand banks, one on the southwest side, and the other on the northwest
side of the island. These are ten or twelve feet above water at all tides,
and are two hundred or three hundred yards long. The smaller has on
it some stunted vegetation and hazel trees.”” Reclus speaks of the Rocas
as a “ veritable atoll of coral like those of the Indian Ocean, enclosing a
lagoon about ten kilometres in circumference.” ®

There is also a valuable article upon the Rocas published anonymously
in the “ Mercantile Marine Magazine.” *

1 Dr. J. B. Regueira Costa, of Pernambuco, has kindly obtained for me speci-
mens of the black rocks of Rocas, but up to the time this report goes to press they
have not been received.

2 Findlay, Alexander George. A sailing directory for the Ethiopic or South
Atlantic Ocean. 9th ed. London, 1888, p. 227-231.

8 f. Reclus. Nouvelle géographie universelle. XIX. Amerique du Sud,

p- 223. Paris, 1894.
4 Mercantile Marine Magazine, XIII., p. 83-50; 65-80; 141-143. London, 1866.

228 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

Cape St. Roque reefs. —It is greatly regretted that I have not been
able to visit the reefs off Cape Sao Roque, for without doubt they
are quite as important and as interesting as any on the Brazilian
coast.

These SAo Roque reefs are upon a part of the coast never visited by
large steamers. Coasting steamers from Pernambuco and Parahyba
touch at Natal, thirty-six kilometres from the southern end of the Mara-
cajahu reef, and this is as near as one can get to them by such con-
veyance. At the time of my visit to Natal, coast of Rio Grande do
Norte, in June and July, 1899, it was impossible for a sailing vessel
to pass the reefs and then return southward. Once past the Cape
it would be necessary to remain there for months for the winds to
change in order to get back to Pernambuco. For this reason when I
reached Natal I turned back southward in order to see the coast
south of Recife.

Our knowledge of the Cape S&o Roque reefs is so scanty that it cannot
be said positively that they are of coral. It is true that Findlay and
Penn both speak of them as being coral, but these authors do not always
discriminate between coral reefs and reefs of other kinds. So far as
can be learned they have never been visited by a naturalist.

The entire group extends from Cape Calcanhar on the north nearly to
Cape St. Roque, a total length of about forty-two kilometres. There are
three groups of reefs: the northwestern, called the Sioba reefs, the
middle group, called Fogo, and the southeastern group known as the
Maracajaht reef. Between these reefs and the mainland is the St. Roque
channel, with a depth of from three and a quarter to three and a half
fathoms. These are therefore barrier reefs.

Lavandeira reefs. — About sixty kilometres west of the Sioba reefs of
the Sao Roque group, on longitude 36° W. of Greenwich, is a large reef
known as the Lavandeira, with several smaller ones both east and west
of it. These reefs are off the point of land known as Tres Irmaos. I
have not examined them, but they are probably of coral.

Jodo da Cunha reef — probably of coral— is about thirty-five kilo-
metres northeast of the mouth of Rio Mossordé, W. lat. 37°. It seems
to be only a small isolated reef.

Ceara reefs. — Of the coral reefs along the coast of Ceara, Spix and
Martius say : “On the sea-coast the numerous corals are used for mak-
ing lime. . . . These banks are the same as the coral reefs further south
along the coast of Pernambuco, Parahyba, and Rio Grande do Norte, and
are covered here and there with thick beds of shellfish. The corals

BRANNER: THE STONE REEFS OF BRAZIL. 229

sent by Mr. Sampaio from the vicinity of Cidade do Forte belong to the
genus Nullipora.” *

At a number of places along the coast of Rio Grande do Norte the
reefs are neither coral nor of the ordinary recent sandstone, but are of
the more resisting iron cemented sandstones of the Cretaceous or Ter-
tiary series. These beds, as has been pointed out in the geological intro-
duction, are often formed at the bases of the bluffs, where, when the
overlying beds are removed, they are in the right position to leave reefs
close to mean tide level. Such are the reefs off the Pittingui, Cape
Branco, Jacuma, etc. Even if the Sao Roque reefs are all of coral, the
chances are that they are built upon some such base as the one here
- mentioned.

The absence of coral reefs along the entire coast from Natal, south
latitude 5° 45’, to the mouth of the Rio Parahyba do Norte, south lati-
tude 6° 57’, is striking. All the reefs within this space are either sand-
stone reefs or hard Cretaceous or Tertiary beds rising to about mean
tide level.

Fernando de Noronha. — The following notes upon the corals of the
Fernando de Noronha archipelago were made during a three months’
visit to that island in 1876, when the writer was a member of the
Geological Commission of Brazil. They are given here, not on account
of their importance, but partly because mention bas been made by Mr.
H. N. Ridley of the “coral reefs” about the group,” and partly because
one might naturally expect to find coral reefs about that group of
islands. .

The main island of Fernando is volcanic, and all the outliers around
it are of similar origin except Ilha do Meio and Ilha Raza, which are of
aeolian sandstone.* Properly speaking there are no coral reefs around
Fernando, though growing upon the rocks about the group are a few
- corals, and still other corals that were not found in place are from time
to time torn up from the ocean bottom and thrown upon the beaches
by the heavy surf. The following is a list of all the species collected
on and about the island. For the identifications I am indebted to Mr.
Richard Rathbun, formerly of the Geological Commission of Brazil, now
of the Smithsonian Institution.

1 J.B. von Spix u. C. F. P. von Martius. Reise in Brasilien, IL, p.799. Miinchen,
1828.

2 Journ. Linn. Soc. Zoology, 1890, XX., p. 559.

3 J. C. Branner. The aeolinn sandstones of Fernando de Noronha. Amer.
Journ. Sci., 1890, XXXIX., p. 247-257.

230 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

: CoRALS FROM FERNANDO DE Noronwa, Braziv.
Collected by J. C. Branner.

rorgonia quercifolia Milne Edwards and Haime.
Gorgonia . . . sp. (?).

- Siderastraea stellata V errill.
Favia conferta Verrill.
Mussa sp. related to Mussa verrillit Rathbun.
Millepora brasiliensis Verrill.

Coat UST SC aS Fe

To this list Mr. Ridley’s collecting has added

7. Astrangia solitarva Lesueur.
8. Favia ananas Lamk.
9. Favia deformata M. Edw. and H.

Professor P. Martin Duncan, who identified Mr. Ridley’s material,
remarks that “ this little coral fauna has the Abrolhos Reef homotaxis.”}

Mr. Rathbun tells me that the species from Fernando are slightly
different from those of the coast reefs.

The Gorgonia quercifolia is washed on shore at the time of the high
tides, or after very rough water. The specimens are found principally
in the Bahia do Sudoest and upon the point of the island east of Santo
Antonio. Some of the specimens are three feet in length. They are
generally more or less bruised by the surf. I was unable after much
hunting to find these corals growing in place. The fishermen insist that
they do not grow near the island, that they are torn up from the deep
sea and brought to the land by the waves. The continued roughness of
the water and ths iack of proper boats upon the island make searching
for these corals very unsatisfactory work. I believe the Gorgonias grow
in or near the mouth of the Bahia do Sudoest, but the small jangadas
of Fernando could not live in that troubled sea.

The Gorgonia . . . sp. (2) is very large and different from anything
yet found on the Brazilian coast. But few specimens of this species
were found. It closely resembles a species figured by Milne Edwards in his
Histoire Naturelle des Coralliaires on Plate B. 2, fig. 6, as Cricogorgia
ramea, but which is unmentioned in the text.

The Mussa, referred to M. Verrillii of Rathbun, can hardly be said to
be rare, though I found but one living specimen on the whole coast.
This was found growing in a tide-pool at the base of Morro dos Remedios.

1 Journ. Linn. Soc. Zoology, 1890, XX., p. 570.

Others were found
washed upon the beaches,
but much broken and worn.
The millepores are uncom-
mon, and the specimens
obtained are poor and gen-
erally worn. None of the
corals growing about the
shores of Fernando are
abundant, and the speci-
mens are very poor as com-
pared with those growing
along the Pernambuco and
Alagéas coast reefs.

There are certain calca-
reous growths about the
shores of Fernando de No-
ronha that are worthy of
mention. These are formed
by Serpulae, corallines, and
other lime-secreting organ-
isms growing upon volcanic
rocks in place, and building
up stony, calcareous rings
that enclose terraced basins
of various sizes.

The accompanying sketch
is of one of the large nests
of diminutive basins to the
east of Morro Francez. In
general appearance these
basins resemble the traver-
tine deposits of Gardner’s
River in the Yellowstone
National Park. The pools
are full of animal life, and
the water is constantly re-
newed by the waves break-
ing over the rocks.

Similar deposits about a
mile long grow upon the
rocks along the southern
coast of the island in front

4

ee

Z ee

Calcareous terraces, north side of the island of Fernando de Noronha.

Fic. 96.

a4 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

of the Viragio. They were not seen, however, on the northern side of
the island.

Mr. Agassiz has described similar forms on the Bermudas as serpuline
atolls. He observes, however, that they are also of Algae, corallines, and
of barnacles, and other invertebrates.

The coral reef of Parahyba do Norte.?—It used to be thought that
the reef of Pernambuco was a part of one almost unbroken system of
reefs extending along the whole coast of Brazil. There was for a long
while more or less difference of opinion as to whether these reefs were of
sandstone or of coral. Asa matter of fact the Pernambuco reef is of
stone, and althongh stone reefs do occur at other places along the coast,
many of the reefs that were formerly supposed to be similar to that at
Pernambuco, and a continuation of it, have been found to be of coral.
Among these is the one at Parahyba do Norte, which was examined
by the writer while a member of the Commissaio Geologica do Brazil.
The form of the Parahyba coral reef and the configuration of the coast
and of the land behind lead to the belief that this coral reef is built
upon and now conceals a reef of sandstone like those of Pernambuco
and Mamanguape, only somewhat lower than the latter ones. It is
worthy of note that the Parahyba reef lies across the mouth of an old
embayment or estuary that has silted up and built out the long flat
peninsula of Ponta da Matta. Corals could not have lived where the
reef now stands until after the peninsula was formed and after there
was a solid bottom to which the polyps could become attached.

The lighthouse at the mouth of the Rio Parahyba do Norte stands
on the outer or seaward edge of the northernmost end of the Parahyba
reef; from this point the reef bears almost due south, keeping approxi-
mately parallel with the shore and on an average of 1100 metres distant
from it. Lying between the reef and the river (Rix Parahyba do
Norte) is a narrow neck of land, on the northern point of which is a
little village known as Ponta da Matta.

The reef is approximately straight, with the irregular zigzag outer face
s0 common on coral reefs. It has a total length from the lighthouse to
the Barreta do Pogo of nearly seven kilometres, and, with the exception
of two narrow passes, or barretas, barely wide enough for jangadas two
metres in width to pass, it is unbroken.

The reef varies considerably in width, but everywhere it is higher cn

1 Bull. Mus. Comp. Zool., XXV. No. 2, p. 253-272, Plates XXIIL-XXVI.

* The observations on the Parahyba reef were made in 1875; a trip to Para-
hyba in 1899 added nothing of importance to the earlier notes.

BRANNER: THE STONE REEFS OF BRAZIL. Dae

the seaward side, and slopes gradually from its outer or eastern margin
inward toward the chaunel. The channel on the landward side of the
reef is a shallow one, being only two metres deep at low tide toward the
upper end ; there are also a few deeper pools behind the reef near its lower
end. ‘The reef at its northern end, near the lighthouse, is low — only a
few points being a foot out of water at the lowest tide. At the northern
end the top of the landward side of the reef is comparatively smooth,
while the outer or seaward side is exceedingly rough and difficult to
walk over. The points of the calcareous growths are too sharp to be
stepped upon, and too weak to sustain a man’s weight, so that when
one tries to walk over them he breaks through and sinks to his ankles
or tc his knees, and gets his legs and feet twisted and bruised. There
are no large corals on the northern part of the reef; the only genus
common is Porites, and of this the specimens are small and insignificant.
The higher parts of the rocks are overgrown by brown polyps which
grow in large patches, and by green, grape-like clusters of seaweeds.
These polyps and seaweeds are found the whole length of the reef.
Following the reef toward the south, its landward side has the bottom
in places covered with sea-urchins, in others with seaweeds or with sand.
Here or there the inner or land side of the reef has a few Milleporae,
Porites, and Favia, though the specimens are all small. Along the
inside near the Barreta do Leitao in the shallow water is a great number
of small red starfishes, of which specimens were collected. Large
quantities of the small, yellow, branching coral, Eunicea sulphurea, grows
upon the inside of the reef along its entire length. It is especially
abundant near the Barreta do Leit&o, where there are also many fine
specimens of Plexaurella. The chief collections made on this part of
the reef were of the corals first mentioned, starfishes, small crabs, and a
few gasteropods. Near the Barreta da Onga the reef is higher, and its
surface much harder than it is near the lighthouse. Below the Barreta
da Onga the surface of the reef is covered with reddish-brown sand, and
this continues to nearly opposite the southern extremity of this section
of the reef. At the lower end of this section of the reef the sand is
about one metre deep. The barrier—the reef with its covering of
sand — continues to increase in height as the south end is approached,
the highest parts projecting nearly or quite one metre and a third above
the water at extreme low tide. On the outer part of the rocks are
many Bryozoa and nullipores, but, owing to the ragged surface and the
breakers that dash upon it, collecting them is difficult and dangerous
even in a sea more than ordinarily calm. The shell of calcareous

234 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

matter formed by lime-secreting animals of different kinds is here
harder than it is near the upper end of the reef, though one may
sometimes break through and sink to his armpits, or even over his head
without touching bottom. It is here that the course of the barrier is
more broken into zigzags.

The Barreta da Onga, about the middle of the reef, is ten or fifteen
metres in width, and allows the heavy swell from the ocean to pass
through. This entrance is deep, and along its bottom grow several
large Millepores, which could not be collected on account of the depth
and roughness of the water. Near the south end, and on the inside of
the reef, there are a few pools containing a number of corals of different
kinds. No Mussas were found on any part of the Parahyba reef.
With the exception of the absence of Mussa harttii and the presence of
Eunicea sulphurea, the fauna of this reef seems to be about the same as
that of Maria Farinha on the Pernambuco coast. The marked absence

of living corals from the northern part of the reef is probably due to —

some extent to the fact that they have been and still are taken out by
the inhabitants living in the neighboring villages for the purpose of
making lime. This burning of the corals for lime must be a very old
custom, and the amount of coral rock thus used must have been at
times very great. The Fortaleza da Barra at the mouth of the river,
built in 1712 on the Ponta da Balea, has pieces of imperfectly calcined
coral in the mortar, and it is plastered in places with lime made from the
corals of this convenient reef. The city of Parahyba gets its supply of
lime from the same source, and the burning is still carried on. The
result is that there are no large coral heads to be found much short of
the southern extremity of the reef. Here, however, are some very rich
pools a hundred metres or so within the barrier edge of the reef filled
with Hunicea, Porites, Favia, Plexaurella, and Millepora. The part of
reef facing the ‘waves of the open sea also abounds in corallines, sea-
weeds, crustaceans, etc., and the cavernous calcareous pieces below look
like fairy grottos as the retreating waves leave the Bryozoa and delicate
Algae dripping with water. The channel between the coral reef and the
land admits of barcagas, which may pass in and out at the Barreta do
Pogo. At low tide, however, only the smallest barcagas can pass readily.
At this last-mentioned barreta the end of the northern reef lies outside
of the northern end of the reef to the south, and the ocean current
brings in through this little opening large quantities of seaweed which
pile up on the south side of one or two of the curaes} nearest the

1 Cural is the name given the fish-traps made of poles driven into the mud or
sand at the bottom of the water. The plural is curaes.

BRANNER: THE STONE REEFS OF BRAZIL. 235

barreta. At one of these the weed was piled up at the time of my visit
to the depth of more than a metre, and lay heaped along the shore for
more than a hundred metres. These piles of Algae are found only in
this one place about the Parahyba reef and always on the south side of
the obstacles.

The coral fauna of the Parahyba reef is not so rich as that of the
Maria Farinha, and of Rio Formoso reefs farther south. The living corals
are scarce, possibly on account of their being used for lime-making, and
the continual disturbance of the heads and prominences of calcareous for-
mations by the lime-burners must affect the life of the reef perceptibly.

Coral reefs between Parahyba and Recife. South of the Parahyba
reef there are no considerable coral reefs again until the Barra de
Goyanna is reached. The reef-like breakers near the shore at Tambiba
and just south of Jacuma& are of Tertiary rocks—those at the latter
place are fossiliferous. South of Tambaba it is possible that there are
some small low patchy coral reefs extending to a little south of Petimbi.
These reefs are only uncovered, however, at the lowest tides, and could
not be examined at the time of the writer’s visit.

The reefs put down on the hydrographic chart as Les Tacis and said
to be uncovered at quarter ebb, I was unable to find. North of the
Barra de Goyanna is a sandstone reef uncovered at quarter ebb, but it
is known here as the Pedra do Galé, and has neither the great length
nor the position given the reef called Les Tacis on the chart. South
of the Barra do Goyanna the sandstone reef is continued in a south-
westerly direction. Outside of and overlapping its south end is a long,
patchy line of coral reefs extending to the Barra do Gerimum. The
reefs are interrupted at the Barra de Catudéma, but they begin again
east of the northern end of the Island of Itamaracd and continue a little
more than half the length of that island. The reef is nearly three kilo-
metres out from the east shore of the island. The corals grow also on
the inside of the Itamaracé reef nearly to the shore. At the lowest
tides the coral banks are exposed at many places between the main
outer reef and the island. The rock is taken out and is used extensively
both for building-stone and for lime-burning. In the heaps found on
the shores, especially at the town of Itamaracd, the most common form
is Porites. Some of the heads of this genus measure 47 centimetres in
length. Millepores are also common. In the shallow water opposite
the church the Porites is especially abundant. The Porttes is known
here, as it is at many other places along the coast, as “cabega de
carneiro” or sheep’s head.

236 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

The dredge brought up very calcareous sands from the shallow waters
between the Itamaraca reefs and the island.

South of the island of Itamaracé there are two reefs, — one on either
side of the Barra de Maria Farinha. The one between this channel and
the land I saw many years ago, and my recollection of it is that it is a
stone reef. I cannot speak positively, however, as the notes then taken
are not now in my possession, and at the time of my last visit the water
was too high to permit a re-examination. The reef east of the Barra de
Maria Farinha is of coral. It has a length of nearly four kilometres.
The Maria Farinha reef is separated from one just south of it by the
Barra de Sao José. This last reef has a length of five kilometres, its
southern end being near the shore at the old fort Pau Amarello. The
Barra do Pau Amarello separates this reef from another shorter coral
reef that runs as far south as Quadras.

These three reefs, Maria Farinha, Pau Amarello, and Quadras, overlap
each other somewhat, their northern ends all lying east of the reefs just
north of them. They are from one to two kilometres out from the
beach.

The near-shore reef south of the mouth of Rio Doce is of sandstone,
and is described on page 59 of this report.

Off the lighthouse at Olinda are some reefs uncovered at the lowest
tides, but they are small and ragged. Ihave not been on them. They
are generally supposed to be of coral, but the existence on shore of the
Tertiary rocks leads me to suspect that they may be the hard parts of
sedimentary rocks.

The coral reefs from Pernambuce to Santo Aletxo.— At and south
of Pernambuco the reefs are of sandstone as far as Boa Viagem. No
coral reef is visible outside of the sandstone reef along this distance, but
about Boa Viagem the sands of the beach are very calcareous.

The first considerable coral reef south of Pernambuco is at Candeias.
At the point of land near Candeias church the coral reef is one kilometre
off shore. Its northern end is opposite Venda Grande, and its southern
end is nearly opposite the Barra das Jangadas, giving it a length of
nearly three kilometres. Corals grow abundantly on the landward side
of the reef, especially through the openings or breaks in it.

The collection of corals made by the Commisséo Geologica do Brazil
in 1875 and afterwards deposited in the Museu Nacional at Rio de
Janeiro was made partly on the Candeias reef.

At the Pedras Pretas north of Cape Santo Agostinho there are many
patches of coral reefs growing upon the trachyte that forms most of the

BRANNER: THE STONE REEFS OF BRAZIL. pss Fi

beach at that place. The patches of coral extend north of the trachyte
exposures for 300 metres. These fragmentary reefs at Pedras Pretas
are all dead so far as the corals are concerned, and are now covered with
worm tubes.

The next coral reef south of Pedras Pretas is at Cupe, ten kilometres
south of Cape Santo Agostinho. It is only a short and broken one, is
600 metres out from the beach with which it is parallel, and lies due
east of the sand point at that village.

At Porto de Gallinhas, south latitude 8° 28’ 30”, is another coral
reef, about four kilometres long. On the beach opposite the reef are
calcareous sands hardened into a soft sandstone. At one place —the
large storehouse on the beach—this rock is hard and very like the
fossiliferous rock of the stone reefs, but further down the coast it is not
so hard, and is more calcareous. These beach rocks have a seaward dip
that would, if continued, carry them beneath the coral reefs ; from this
it is inferred that the landward portions of the coral reefs are newer than
the sandstones.

There is another coral reef just south of this one, at Maracahype. It
lies across the mouth of Rio Maracahype, across Serramby point and
passes on to the south, ending west of the Island of Santo Aleixo. Its
total length is about nine kilometres. There are many small breaks in
it within this distance. The most abundant species of the corals is
Porites, heads of which, with other coral rocks, are gathered here for the
manufacture of lime.

Santo Aleixo. — The island of Santo Aleixo, also known on the hydro-
graphic charts as Navigators’ Island and Donally’s Island, is opposite
the Barra de Serinhaem, and about two and a half kilometres from the
shore. The island is of eruptive origin and the rock composing it is a
grayish-green quartz porphyry. It is 883 metres long, its greatest
length being from north to south. On the southeast corner is a little
hill 23 metres in height, and on the southwest corner is another smaller
and lower hill.

There is a quarry in the igneous rocks on the south side of the island,
and east of the quarry are patches of a calcareous fringing reef, which
is narrow near the quarry, but it widens to about 40 metres. From this
point to the southeast extremity of the island the outer margin of this
fringing reef makes nearly a straight line, though the land curves in to
the distance of nearly three hundred metres, forming a sort of shallow
bay. The reef ends at the southeastern point of the island. It is low,
not rising more than a metre out of the water at low tide, and present-

238 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

ing the general features of other calcareous reefs, being by turns hard
and flat, cavernous, shelly and fragile, and filled with pools of water
containing seaweeds and a few small corals. The part nearer the igneous
rocks is the more solid; further from the shore it becomes more cavern-
ous, the most fragile places being where the reef has its greatest width.
It is highest along the outside, where it is covered by the dark and
brownish polyps, seaweeds, and other calcareous growths. The pools
in this reef have in them a few small corals, Stderastraea and Favia,
the specimens of the latter genus being the finest I have seen on
the Brazilian coast. The specimens of Siderastraea are small, none
being found larger than a man’s head. It is probable that many of
the corals have been removed from this reef for the purpose of making
lime.

To the oceanward of the southeastern corner of the island where the
fringing reef ends. the rocks are rough and are washed high up by the
waves, which break here with full force. Wherever the water breaks
over the top of one of the high rocks at this corner of the island and
runs down the inside surface, this inside is covered by calcareous terraced
rings which grow along the sides and over the surface parallel to each
other like broken contour lines. These rings contain little pools of
water one above another, and this water is continually renewed by the
splashing of the waves and by spray from the ocean. These little bands
are about three centimetres in thickness, are from eight to thirteen cen-
timetres high, and are surmounted by rows of barnacles.

The outer side of the rocks along the northeast part of the island
appears to be crusted over by dark-brown corallines. Near the middle
of the east side of the island there is a large pool among the higher
rocks of the shore, the water of which is continually renewed by the
waves ; this pool contains a few fish, corals, ete. —all quite beyond tide
level. It is only by leaping that the waves reach this height, but the
island standing so well out at sea receives the full force of the waves,
and they are thrown by the huge blocks of rock at the base of the bluff
high into the air, and are thus carried as spray or as waves high up the
sides of the rugged cliff.

Near this large pool and supplied in the same way are two other
pools, one a little above and emptying into the other. The two are
about the same size, being about twelve metres in length by one to two
metres in width, and a metre or more in depth. These higher pools
contain excellent exhibitions of the wearing or dissolving power of the
sea-urchins upon rocks. The sides of the rocks are almost completely

BRANNER: THE STONE REEFS OF BRAZIL. 239

covered with the holes made by these animals. Hard as this igneous
rock is they have succeeded in boring holes in some places to the depth
of nearly five centimetres. This sea-urchin is Echinometra subangularis
(Leske) Desme — the same species as that found upon the stone reefs at
the city of Pernambuco.

On the north side of the island, where the waves are not so violent, a
calcareous reef is forming among the eruptive rocks.

The coral reefs between Santo Aleixo and Maceio. There are several
small reefs south of Santo Aleixo and north of Rio Formoso. Of these
the largest are one lying off Gamella, and another a little to the north
and to the landward of it.

At Rio Formoso the sandstone reef lies across the mouth of the river,
and corals grow over the seaward side of the sandstone. Nearest the
Stone reef the corals occur in irregular patches, but further out they
form two well-defined reefs. The positions of these reefs are shown on
the map of Rio Formoso, Figure 51, p. 83.

The channel between the corals growing on the outer face of the stone
reef and the coral reef to the seaward of this has it perpendicular sides
covered with fine specimens of living corals. The genus Mussa is espe-
cially abundant and fine. The bottom Where not covered with fine mud
has growing over it fine specimens of Millepores, which are popularly
known hereabout as tapitdngas.

It was on this inner coral reef that many of the finest Specimens
belonging to the Commissio Geologica do Brazil were collected by the
writer in 1875. Upon the extinction of the Commiss&o this collection
was turned over to the Museu Nacional in Rio de Janeiro. The corals
from these reefs have long been burned for lime, and the most accessible
of the large heads have been removed by the lime-burners.

The outer Rio Formoso reefs cross the sandy Manguinho Point south
of the river and continue as parallel reefs halfway across the bay north
of Tamandaré.

Off the point north of Tamandaré (see p- 161 for chart) the coral reefs
begin again as broad double reefs, and cross the mouth of Tamandaré
Bay, leaving one considerable break at the bar, and continuing south of
it as a single reef. This reef stands well out of water at low tide.
Tamandaré would probably be an excellent place to study the reefs of
this part of the coast. The town is large enough to offer facilities that
cannot be found at all places, the bay is accessible to large vessels, and
the extent of the reefs, their height, and their having channels between
them would be advantages not to be found at many places on this coast,

240 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

The presence of the new Brazilian quarantine station might also occa-
siovally put a steam launch at the disposal of investigators.

Ilhetas Point is at the southern end of the Bay of Tamandaré.
Here there are two coral reefs : one small one connected with the shore,
the other three hundred metres outside, separate from the shore reef, and
about three kilometres long. Both these reefs are uncovered at low
tide. The one on shore has the beach sand spread out over the top of
it. On the south side of Ilhetas Point the inner reef is but slightly
uncovered (one decimetre) at ordinary low tide. This part extends out
from the beach, with which it makes a low angle for three hundred
metres.

These onshore coral reefs are all dead. But few living corals are
found in the shallow tide-pools over their surfaces, and these are the
hardy Porites and Favias in small heads. The bodies of the reefs are
solid, and their surfaces are thinly covered with seaweeds and sponges.

South of Dhetas Point the coral reef stands further and further out
from the beach, until it ends, after several small breaks, at the Caixao de
Una.

South of the Caixao de Una the reef begins again in force and with
small breaks continues for a distance of twenty-four kilometres to the
Barra Grande, east of the city of Maragogy. Throughout this entire
distance the beach sands are very calcareous, often almost entirely of
triturated shells and corals.

At Sao José Point the seaward face of the reef is less than one kilome-
tre out from the beach. It is one hundred metres wide on the highest
part and stands about two metres out of water at low tide. The top of
this reef is exceedingly rough and jagged and is covered with barnacles.
The surface is all dead save the Porites and Favias found in the tide-
pools. From the outer face of the reef to the shore the bottom is most of
the way covered with corals in patches of various sizes, the tops of which
are uncovered at the low spring tides. In the channels between these
higher portions live some corals. The channels are of all widths, from a
few decimetres to seventy-five metres or more.

The corals are burned at Sao José for lime, and as the large solid
heads make better lime than the average of the reef it is probable that
the finer heads have been removed for this purpose.

On the beach at Sio José the calcareous sands have formed a soft
rock full of shells and calcareous Algae.

At the point of land next south of Rio Persintinga there is a coral reef
uncovered at low tide within a stone’s throw of the beach, and round the

m. =
ian

BRANNER: THE STONE REEFS OF BRAZIL. 241

bend in the shore this reef connects with the beach. The part here
exposed is only about one hundred and fifty metres long by fifteen
metres wide. The great reef opposite this point stands well out of the
water at low tide. Five kilometres south of the mouth of the Rio
Persinunga the coral reef is double.

At Ponta do Mangue the outer edge of the coral reef is just one kilo-
metre from the beach. The tide was not very favorable for an examina-
tion when this reef was visited. The width uncovered was one hundred
and fifty metres, but at the lowest tides the width is very much greater.
It stood 1.3 metres out of water, but it is considerably higher at the
lowest tides, — probably as much as three metres.

The surface of the reef here is exceedingly irregular and etched, and is
all dead save the Serpulae and barnacles that grow over the dead corals,
and the few Porites and Favias and such other forms as thrive in tide-
pools. Landward of the main wall of the reef the coral rocks rise in
patches that are separated from each other by a labyrinth of channels of
various widths.

A chemical analysis has been made in duplicate of a typical specimen
of the rock of which this Ponta do Mangue reef is composed with the
following results : —

ANALYSIS OF THE REEF ROCK FROM Ponta DO MANGUE, STATE
or ALAGOAS, BraziL.

Sample collected by J. C. Branner, July 28, 1899. R. HE. Swain, analyst.

No. 1 No. 2

ealcimmoxide (CaO). >. BS 46001 46.03
cova STF ls £24 0) a A a ian 5) 7.05
ReGHeL@ P44 Me as .85 88
JU TG 0) ec 56 59
EAN Sue ks ee oe) & ) & Bace trace
Carbon dioxide (CO,) ..... =. 4294 42.96
Sirens.) 5. -. eae | ROS 1.29
Phosphoric anhydride (P, 9) 5 ae 27 .26
Ciiorme (Clr... 2°. Pests 31 .28
VPS 1810) a er re .79 77
IRCMMUME OL ye We nly uw We SOROO 100.11

If all the calcium present were there as carbonate, and the rest of the
carbon dioxide as magnesium carbonate, it would be equivalent to : —
Carbonate of lime (CaCO,) .-. . . ... . . 82.19
Carbonate of magnesium (MgCO,) . .. . . . 12.98

1 Probably as chloride.
VOL. XLIV. 16

242 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

South of Barra Grande the line of coral reefs continues with breaks to
the Porto de Pedras at the mouth of Rio Manguéba. South of that
place they are almost continuous to the mouth of Rio Camaragibe,—a
distance of twenty-four kilometres. The seaward face of this reef aver-
ages something more than a kilometre off the shore.

At the Barreira do Boqueirao an inner reef, having its northern end
well off shore, swings round and comes squarely against the beach at its
south end, the beach sands lying on top of the dead coral reef.

At Sao Miguel dos Milagres (S. lat. 9° 18! 30!) the coral reef is
rather closer to the shore than usual. One kilometre south of there a
coral reef is uncovered
on shore for a short dis-
tance; its south end
swings outward away
from the beach into deep
water.

Three kilometres
south of Sao Miguel
there is a coral reef un-
covered on the beach at

stream. This piece of
reef has been dead for a
long while. Its surface

Fic. 97. Map showing positions of two coral reefs has been pitted and
near Sao Miguel ; the reef on shore is dead and worn by waves and sand,

is, pantly covered Dy aut then buried beneath the
encroaching beach sands, and now again it has been partly uncovered
by the shifting currents. The freshly uncovered surface shows the com-
position of the reef much better than it can be seen upon the ordinary
dead or even upon living reefs. The rock is mostly coralline and most
of the coral imbedded in this mass is Porites. The Porites form less
than half of the rock, —perhaps a third of it.

This piece of reef runs out more than one hundred metres from the
shore at mean tide, and at low tide a width of nearly five hundred metres
is exposed.

One kilometre south of this exposure the sand flats exposed at low
tide connect with and overlie the offshore dead coral reefs. The dead
reef is exposed along the beach for more than two kilometres, and the
water between it and the main reef outside (seaward) is very shallow
and full of coral rock.

the mouth of a small —

+e

BRANNER: THE STONE REEFS OF BRAZIL. 243

At Marceneiro Point coral reefs are exposed on the beach at low tide
with the calcareous beach sands lapping over them. Inthe bank above
the beach are exposed the partly consolidated calcareous sandstones
shown in Fig. 58, p.90. Porites and corallines are the commonest forms
in the reef here.

At the bottom of the embayment south of Marceneiro there are coral
reefs along almost all of the beach, and soft calcareous sandstone is
exposed in the 1 to 2.2 metres bank above it. These coral reefs rest
directly upon Tertiary shales.

Fic. 98. Section showing the relations of the coral reef to the Tertiary at
Barra do Passo.

There is a decided break in the coral reefs off the mouth of Rio Cama-
ragibe, and they appear to begin again only five kilometres south of that
stream. Thence southward to Ponta Verde north of Maceio the coral
reefs are more broken and fragmentary than they are to the north.
These fragmentary reefs were not examined except where they lie along
the beach. Some of the beach exposures are of more than usual inter-
est on account of their showing the relations of the coral reefs to the
stone reefs and to the eroded Tertiary strata of the land.

South of Rio Santo Antonio Grande the coral reefs for two or three
kilometres are almost connected with the beach, — perhaps quite so at
the lowest tides.

At the point 1.4 kilometres south of Rio Sapucahy there is a sandstone
reef overlying the coral reef. In view of the importance of this locality
in showing the geologic relations of the stone and coral reef, I repeat
here what has been given in the description of the Sapucahy stone reef:
“Following the beach southward from the mouth of the Sapucahy
[a small river of the State of Alagéas about thirty kilometres northeast
of Maceio] it curves gradually seaward and then back landward again,
forming a sandy point, part of which is shown on the accompanying
map. Ata distance of 1.4 kilometres from the mouth of the Sapucahy,
this sandy point laps over one of the coral reefs that here run parallel
with the coast. And just at this point on the beach begins another

244 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY.

reef of sandstone. This particular reef is eight hundred metres long,
not including some detached fragments lying beyond its southern end,
and not shown on the map herewith, which would give it a total length
of something more than a kilometre.

“A fact of unusual interest in regard to this bit of reef is that 7
overlies a dead coral reef. The overlap is plainly visible at many places
where re-entrant angles have notched the stone reef, or where large frag-
ments have been left isolated but fast to the coral reef. The coral reef
visible here at low tide is from one hundred to two hundred and seventy
metres wide, measured from the outer margin to where it is overlapped
by the stone reef or by the beach sands. This coral reef is almost per-
fectly flat and level. Not a single living coral could be found on its
upper surface ; the coral most abundant in the rock itself is Porites.

“ Outside or seaward of this reef is still another coral reef with which
the inner one is not connected, at the water’s surface at least.

Fic. 57. Section across the stone and coral reefs at Sapucahy. The vertical
shading on the right represents the coral reef.

“The sandstone reef lies at a higher level on the beach than the coral
reef, and has throughout most of its length a decided seaward dip. At
the southern end of its contact with the beach, however, the dip is re-
versed and the bedding looks very much as if it had been formed by
sand washed over and behind a low beach or spit. The rock is in some
places rather soft, in others it is quite hard and rings when struck with
the hammer.”

At Paripueira and southward the coral rocks are exposed at the lowest
tides in many places and over large areas. At.this place there is a
considerable business in the burning of coral rock for lime.’

Off the mouth of Rio Pioquinho there are at least three coral reefs,
the one nearest shore being three hundred metres out from the beach.
Off the sandy point near Pioca there is one coral reef one hundred and
fifty metres out from the beach, and the interval contains many isolated
points of coral rock, while outside is a second reef about four hundred
metres from the beach. These reefs are broken in front of the bay just

1 The extraction of these rocks in the State of Alagéas is under the supervision

of the Captain of the Port at Maceio, and the burners are taxed by the govern-
ment in proportion to the size of the kilns burned.

BRANNER: THE STONE REEFS OF BRAZIL. 245

south of Pioca, and south of the bay they continue again as three or four
overlapping reefs.

Just above the mouth of Rio Santo Antonio Mirim that stream passes
over a submerged reef. This reef was under water when it was passed,
but judging from its jagged uneven surface over which we had to wade
it is thought to be a coral reef. Both ends of the reef are covered by
sand spits.

At Riacho Doce, south latitude 9° 36’, and from there to Garga Torta
are several exposures of coral reefs on shore in addition to the large reefs
outside.

As pointed out in the geological introduction, the rocks exposed along
this part of the coast are probably of Tertiary age, beginning with heavy
basal conglomerates containing large boulders of granite. Resting upon
these conglomerates is a series of sandstones and bituminous shales
wrinkled and faulted. These sedimentary beds have been cut off by
the waves, and on top of the eroded surface have grown the coral reefs.
In places the corals cover the granite blocks washed out of the basal
conglomerates. At one place for a distance of thirty metres there is a
sandstone reef on top of a coral reef which in turn rests unconformably
on the upturned edges of the Tertiary shales. At another place the
sandstone reef has been more or less shattered by the waves, but frag-
ments of the stone reef rock from three to eight metres long overlie the
coral reef, and in some cases they overlie coral reefs that rest upon
granite boulders for a distance of two hundred metres. Again, two
hundred metres north of Garga Torta there is a coral reef exposed at
the edge of the beach for a distance of one hundred metres. The rela-
tions of this reef to the other rocks cannot be seen. At low tide it is
one metre out of water.

Out seaward from these beach exposures are more than twenty patches
of coral more or less isolated. They are generally not more than seventy
metres across, — some are less
than seven metres, — flat on
top with openings between 2%
them. These patches extend
a kilometre out from the
beach. South of Garga Torta
are similar patches. The following is an outline sketch of one of these

JOYE
Sel Je ee

ery

oma Jive

Fic. 99. Coral reef covered by worm tubes
south of Garea Torta.

small patches.
The harbor at Maceio is formed by the southern end of a coral reef.
This reef is about three kilometres long and varies in width from eight

246 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

hundred metres at its northern end, where it joins the beach,-to only a
few metres in its narrowest parts. At one point east of Jaragué there is
a big solitary mass of coral rock rising three metres above the general
level of the reef. Mr. F. Ambler of the Alagéas railway kindly made
photographs of this block from which the illustrations on pages 160 and
161 were made. The form shows that it has been undermined and one
end of the block has settled, lifting the other end into its present position.

South of Maceio the reefs have not been examined. I was credibly
informed that the one at Rio de Sao Miguel was of sandstone, and that
south of that place the reefs are very fragmentary. It is also a remark-
able fact that there are no coral reefs (known) between the mouth of the
Rio Sao Francisco and the city of Bahia.

The Bahia reef.— At Bahia there is a great coral reef off the east
shore of the island of Itaparica. This reef was studied by Mr. Rathbun
in 1875-76, and a paper on it was published by him in the “ American
Naturalist.”* Part of Mr. Rathbun’s paper appeared in the Archivos of
the National Museum at Rio de Janeiro.* I did not therefore visit the
Itaparica reef, but have depended upon Mr. Rathbun’s paper, which is full
and is given here at some length : —

“The long island of Itaparica, often called the garden of Bahia, fills up
almost the entire southwestern quarter of the large Bay of Bahia, and contracts
its entrance to a width of about five miles. Its outer coast, running obliquely,
faces for the most part the open sea, and is at the mercy of its boisterous waves.
Skirting the central portion of this coast for a distance of nearly nine miles is
a slightly elevated coral reef, long since abandoned by true living corals and
given over to another class of workers, who are putting on the finishing touches
and coating it with a hard and durable substance.

“ This reef begins directly opposite the city of Bahia, in front of a little rocky
point named Jaburi, and stretches away southward, in the general trend of the
shore, enclosing behind it a narrow and shallow channel which, at the most, is
searcely one-fourth of a mile in breadth, and generally less. It is most perfect
toward the northern end, and has, at irregular intervals, numerous breaks or
openings which admit the smaller boats that ply along the shore. Approach-
ing close to Penha, another rocky point about three miles from Jaburd, it ends
abruptly ; but commencing again to the south, it runs onward to the Ponte da
Cruz, terminating for good on the rocky shore. The study of the geology of

1 For a description of the Maceio reef see Prof. A. W. Greeley’s paper, —
appendix to this paper, p. 268-274.

2 Richard Rathbun Brazilian corals and coral reefs. American Naturalist.
September, 1879. XIII. p. 589-651.

8 “Q recife de coral do Mar Grande.” Archivos do Museu Nacional, III., p. 174-
188. Rio de Janeiro, 1878.

BRANNER: THE STONE REEFS OF BRAZIL. 247

the island has shown that the reef follows the submerged, out-cropping edges
of a series of heavy beds of sandstone, which, at times, bring up on the shore
in the form of rocky points. On this solid base the reef appears to have been
built, and where, finally, at the south, the sandstone leaves the sea and lies
upon the beach, the coral reef ceases to exist.

“The reef is slightly zigzag in its course, and both edges are very jagged,
deeply indented and bordered by projecting or outlying masses ; but so irregu-
lar in every part that it would be quite useless for us to try and describe it
accurately. At the northern end it is generally elevated on the outer side and
low and level on the inner. The higher portion varies greatly in width and
height, and is never flattened on top; it rises rapidly, often abruptly, from the
water, but descends more gradually on the inner side to a level of about one
foot above ordinary low tide. From here there extends inward a very flat
surface, which is generally quite broad but may narrow down or even nearly
disappear. Almost everywhere along the inner edge, but more commonly at
the ends of the reef and about the openings through it, we find many outlying
masses which are often partly continuous with the low, inner surface, but more
frequently quite detached. They attain all heights up to that of the lower
surface, but never reach above it; the average depth of water around them is
between three and four feet. The outliers on the outside of the reef are merely
low, ragged, angular projections from the reef itself, and are never much ex-
posed, even at low tide.

“ Between the two divisions of the reef, the elevated outer portion and the flat
inner one, there is the most marked contrast. While the latter has been com-
pletely smoothed and rounded off, so that scarcely any angles remain upon it,
the former retains all the possible roughness that could be brought together on
sonarrow anarea. The entire raised mass of rock is full of holes of every imag-
inable size and shape, the margins of which are always acutely angulated. Every
little surface that is not pointed in itself is surmounted by a large and strong
barnacle with sharply-edged valves, and large clusters of digitate projections
stand up at frequent intervals. This combination of surface is a very uninvit-
ing one to look upon, but it is far less pleasant to climb over it or walk along
its outer part. The outer slope is by far the most irregular, as the waves, aided
by an army of sea-urchins, have broken into it and hollowed out thousands of
ragged holes, which, lying concealed beneath the seaweeds, might lead to many
accidents were the reefs more frequented.

“The outer portion of the reef is of a dark and rather rich brown color when
wet by the waves, but nevertheless has quite a dead appearance. Examining
carefully this brown rock, it is seen to consist generally of an accumulation of
very small worm tubes, closely packed together and forming a very hard mass.
The surface of the low inner level is of a much lighter color, a rather faded
brown, and looks even more lifeless than the part we have been describing; no
barnacles or other larger animals grow upon it.

“What forms of life occur about the reef? On the outer side, reaching to a
height of a foot or slightly more above ordinary low tide, is a luxuriant growth

248 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

of seaweeds. Over the same zone, but not so apparent, spread encrusting
nullipores, which, though resembling lichens in form, are so highly charged
with lime as to produce a hard coral-like substance. This is one of the most
important organisms living on the reef at present, and while aiding to protect
it from wear is also building it up. The barnacles and worm tubes of the
upper portion we have already referred to, and we have also stated that over the
inner surface there seems to be nothing alive. As we enter the many open
pools and passage ways of the inner margin there is scarcely more to be seen.
Only here and there does a small mass of coral grow, usually a Siderastraea or
a Favia. Seaweeds and delicate tufted hydroids and bryozoans hang from the
sides of the pools, and a few shell-fish and star-fish lie on the sandy bottom.
Small, brilliantly-colored fish dart hither and thither, but the life is not what
we are taught to expect about a coral reef.

“The features we have so far been giving are those of the northern section of
the reef. Going southward a short distance, the elevated outer mass gradually
diminishes in size, until it is reduced to a slightly raised border along the sea-
ward margin of a broad and flat reef. Still farther south the entire lower sur-
face, without the raised margin, seems lifted bodily upwards to form a high
massive wall, like that of an immense fort, flat above and perfectly square at
the sides.

“ Between the points of Penha and Cruz we find a varied structure, generally,
however, only a repetition of the forms already described. The reef is often
two or three times as broad as at Jaburt, but near its southern end it becomes
very irregular and much broken up, existing as a line of detached reef masses.
The passage ways through the reef are sometimes mere simple breaks, cut as
squarely and neatly as though the work of man; at other times, however, the
edges of the reef bordering them are carried obliquely inwards some distance
toward the beach, enclosing a narrow entrance channel. These inner pro-
longations, although generally low and level, have the same structure as the
main reef.

“ Within the reef the water is always shallow; frequently the bottom lies so
high as to be quite exposed at low tide, and it is covered nearly everywhere by
a thick deposit of coral fragments, cemented together by carbonate of lime. The
corals are not in place but lie heaped together in every conceivable way, as
though they had been violently broken from the reef at some former time and
thrown inside by the waves. All the commoner forms are there, Millepora,
Siderastraea, Orbicella, and Mussa being the most conspicuous, and they are some-
times nearly perfect, but most often broken into irregular masses, large and
small. The majority are also coated over with a thin nullipore crust, as though
they had been dead a long time before they were swept from their proper dwel-
ling place. This coral deposit has considerable thickness near the middle of
the channel and thins out gradually toward the beach.

‘The extreme southern end of the reef is very low, and near tothe beach. It
breaks down abruptly on the outer side, but on the inner is bordered by a thick,
consolidated layer, which reaches so nearly its own level that it is often difficult

eS

——S a

BRANNER: THE STONE REEFS OF BRAZIL. 249

to make out the dividing line between the two. A close examination, however,
discloses the upright corals in the one and the prostrate fragments in the other.

“ A great difficulty stands in the way of our determining the intimate structure
of this nearly extinct reef, whose outward appearance and surroundings we
have so fully discussed. It has evidently not been formed entirely by those
agents at present occupying its upper and outer surfaces; but the remains of
the real builders, whatever they were, are entirely covered up and hidden from
view, excepting at the one point at the southern end just inentioned. We must
resort to artificial sections, no easy undertaking in a coral reef.

“ Breaking with hammer and chisel into the higher part of the reef, we obtain
specimens of a very hard, compact limestone, partly of a nearly homogeneous
structure, partly marked by straight or wavy lines of lighter and darker color-
ing; these two kinds of structure are intermingled with one another without
order, sometimes one, sometimes the other predominating. The former has
resulted from the masses of serpula tubes by the complete filling in of their
winding cavities and the spaces between them by carbonate of lime, until no
trace of the original structure remains. The latter is due to the growth of in-
crusting nullipores, one thin layer upon another, until quite a thickness of rock
has been the result.

“Tt is evident that the serpulz and nullipores were at one time living together
over the surface of the reef, and by their combined action has been formed most,
if not all, of its outer raised portion, which is sometimes over four feet high and
twenty-five feet across. The barnacles are generally broken from the reef when
dead, but are sometimes overgrown by worm tubes and thus become imbedded.

“ Here and there, the slaves, in procuring lime, have quarried into the low
inner part of the reef, and even into the high wall-like portion. Good sections
for study are thus formed, and they tell us of what the reef consists. Many
large heads of Orbicella, Acanthastraea, and Siderastraea stand there exposed in
their original positions, and when cut through show their structure to be as
open and perfect as though they were still living. With them are many
large millepores and nullipores, and all the intervening spaces are filled in with
a compact calcareous substance.

“Our structure began as a true coral reef, stretching along the submerged
rocky ledge. The water was very shallow, however, and the reef soon reached
a level above which its corals could not live. Over them nullipores began to
grow, but probably while the reef was being raised by other causes than those
of growth, large numbers of these dead and partly entombed corals were swept
inward by the waves. Nullipores continued to thrive and serpnlae came in to
aid them, but with these forms we are already familiar.”

Reefs between Itaparica and Caravellas.— South of Itaparica the
coral reefs have been but little studied, probably on account of the
difficulties of transportation along this part of the coast.

1 One can get an approximate idea of these difficulties when I say that the
Bahia company whose steamers run as far south as Vigosa and the Abrolhos have

250 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

Extensive coral reefs are reported at and north of the Port of Camamu.
Spix and Martius report from the “inland water of Camami Madre-
pora uva [Dichocenia uva E. & H.] which we noted near M. astroides
and acropora.”1 The next place south of there at which corals are
known is at the Lagda de Itahype, south latitude 14° 40’. This place
was visited by Spix and Von Martius in 1818, and is described by them.?
The location is so remarkable —the bottom of a fresh-water lake, seven
kilometres from the sea—that I give at length what they say of it.
This lake was formerly known as Lagoa de Almada, and it is under this
name that Spix and Martius speak of it. It is now more commonly
known as Lagéa de Itahype.

“On the shore it [granite] is exposed here and there in great naked
banks through which trough-shaped depressions and zigzag channels seem to
show a connection of the ocean with the lake in early times. There is still
stronger proof of this connection in the form of the shore which toward
Itahype and the sea on the southeast is flat and sandy, and especially in the
presence of extensive coral reefs. These reefs may be seen at several places
in the lake at a depth of from six to twelve feet, and the rock is quarried for
lime and for building stone. It is broken up with wedges and crowbars and
the pieces raised by divers. . . . The business is not very profitable because
the coral banks in the great bay of Camamu are more easily worked. Those
seen in this lake are exclusively madreporic. . . . Madrepora [Heliastraea]
cavernosa, hecagona, astroites, Lam. n.s. There are also in the neighborhood
banks of sea-mussels cemented in quartz sand but being- impure and difficult
to break they are not quarried. The water of the lake . . . is now fresh
probably through the agency of Rio Itahype, which has gradually washed it
out, or freshened the water cut off from the sea.”

The reefs shown on the charts at Ilheos are crystalline rocks, — not
corals. South of Ilheos the first coral reefs are those off Ponta Guait
and are known as the Araripe reefs. They form part of a large group
that extends across Ponta de Santo Antonio northwards for some nine

no set dates for sailing. One depending upon these steamers is liable to have to
wait at Bahia from one to three weeks or even a month, expecting the announce-
ment of a date any day, and consequently unable to leave that city in order to
utilize the time elsewhere. After nine days waiting at Bahia, I took a steamer for
Ponta d’Areia and reached that place in eight days from Bahia. At the last-named
place I was compelled to wait twenty-five days for a steamer to Rio de Janeiro.
The trip that ought to have taken at the most seven or eight days consumed just
thirty-eight days.

1 J.B.von Spix u.C.F. P. von Martius. Reisein Brasilien. IL. p.710. Miinchen,
1828,

2 Reise in Brasilien. IJ., p. 684-685. Miinchen, 1828.

BRANNER: THE STONE REEFS OF BRAZIL. 251

kilometres, and southward to and including the great Itassepanema
reef at the northern end of the Bahia de Cabral. Their total length is
about twenty kilometres to the Boqueirao Grande entrance to that bay.
These reefs all draw away from the coast somewhat at their northern
ends. They are all covered at high tide, and uncovered at low tide.
There are various small passages through the Araripe reefs, and there
is a canal between the reef and the shore for small crafts only. The
northern end of the Araripe group is not shown on the charts of the
coast. The southern reef of this group is known as Itassepanema.
There are two yellow sandbanks on it, one of which is known as the
Coréa Alta; this bank is not covered at ordinary high tide.

The Itassepanema reef is somewhat higher at its southern than at its
northern end. Its surface is very flat and smooth.

The Alagadas reefs south of the Boqueirao Grande are also of coral,
but they are small as compared with the Itassepanema reef.

At the southern end of the Bahia de Cabral a line of coral reefs stands
out from Ponta Vermelha and Coréa Vermelha in a nearly northeast
direction. This reef continues from the point marked “ Vermelha
Bank” on the chart to and south of the mouth of Rio Manguinha. Its
total length is about eight kilometres. It curves outward and away
from Ponta Grande and leaves between it and the beach a canal for
small crafts at high tide.

The Recife de Fora, or Baixo de Fora, as it is called on the chart,
just north of Porto Seguro, is a coral reef, reported by the coast pilots
to be ‘not less than half a league wide,” east-west.

The next coral reefs south of Porto Seguro are those known as the
Itacolumis, south latitude 16° 53’. I did not visit the Itacolumi reefs.

Coral reefs off Caravellas. — The Parcel das Paredes is the most ex-
tensive group of coral reefs on the Brazilian coast. They have a total
length of about thirty-three kilometres, and a maximum width of about
twenty kilometres. I visited them only once, —in September, 1899, —
but I traversed almost their entire length and breadth in a whale-boat
that allowed me to pass freely through the shallower parts of the
channels. I did not, however, see the extreme eastern edge of the
reefs where they receive the heaviest surf.

The highest part of the Parcel das Paredes reefs is at their northern
end, and is known as the Recife da Lixa, or Shark Reef, on account of
the great number of a certain kind of sharks about this part of it.

But the whole of this group from one end to the other, and without
any exception, is completely covered by water at high tide. It will be

Doe BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY.

seen that these reefs are a long way out from the shore. In order to
spend a second day on them it was necessary to anchor our boat and
remain there over night. When the tide was high, except that the sea
was not very rough, to all appearances we might have been anchored in
the middle of the ocean.

The water was a little short of two metres deep on the higher parts
of the reef at high tide ; judging by the posts planted on the reef, I take
it that the tides here rise about three metres.

These reefs are traversed by irregular channels from one to ten
metres deeper than the top of the reef, and varying in width from three
or four metres to half a kilometre or more. The whale-fishers of the
Barra de Caravellas have planted here and there along these channels
tall poles to serve as guides in sailing across the reefs when the water
is shallow on top of the rocks, and to mark anchoring places for their
boats at night.

When the tide is ebbing the first visible signs of the reef are muddy-
looking splotches in the water; these get browner and yellower as the
water gets shallower, until the rocks begin to appear at the surface.
When the reef is quite uncovered it has a deep yellow color, — between
lemon and orange. The water itself looks yellow and muddy over the
reefs, but this is deceptive, for it is perfectly clear, — at least it was so
during my visit.

The Lixa reef is the flattest and smoothest I have seen on the coast
of Brazil. Except on the edges, where it is always more or less ragged,
it has the appearance of being
one solid compact mass of coral
rock built up to an even level.
The view over its surface at low
tide reminds one of a great prairie
covered with short dead grass, the
sky line unbroken save here and
there by a few black points, —
blocks of the reef rock broken
out by fishermen in search of squid or fish.

The top of the reef is dead so far as the corals are concerned. Only
two forms were found alive in the shallow pools on the surface, — Porites
and Favia, —and these are all small and apparently stunted. Other
polyps are also abundant, but the patches are small and the species few.
Living corals are found only along-the edges and over the bottom of
the channels that cut the reef, and in the isolated patches that rise

Fic. 100. Profile of the edge of Lixa
coral reef.

BRANNER: THE STONE REEFS Of BRAZIL. 253

near the margins of the reefs. These living corals are fully a metre
below the reef’s flat surface.

The surface of the reef — that is, of the large solid portions that rise
above water — usually slope off rather gently into the water at all points
where it was examined. The slope of from three to ten degrees begins

fie ena cai at i i a
J a a J0cmme ~-34

Fic. 101. Profile of the edge of Lixa coral reef.

from fifty to one hundred metres back from the edge of the water at
low tide.

At several places this gentle surface slope continues beneath the water
for a hundred, or even several hundred, metres, where it comes to a
sudden drop off into deep water.

The patches of living corals that rise from the deeper waters in the
channels and at the reef margins are of many sizes. Their forms vary,
of course, but not to any remarkable extent. The following are true

Fig. 102. Vertical sections showing the forms of growing coral masses on
the Lixa reef. The broken line represents low tide.

profiles as nearly as they can be made without minute measurements,
and they include as great a variety of forms as was seen.

254 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY.

It is quite noticeable that these growing projections lean with some
uniformity in a certain direction. These directions, however, are not
always the same. The most marked cases I noted were in east-west
channels, where most of these points leaned toward the west. I suppose
these forms to be due in some way to the influence upon the growing
polyps of the movement of the tidal currents through the channels.

The forms of the growing portions as seen in plan are much more
varied ; indeed, there seems to be no limit to the shapes of these masses
below a certain level. This
certain level I take to be the
depth at which the polyps
are injuriously affected by any
agency whatever at the lowe
est spring tides.

These growing portions
start out from the larger reefs
like long knotted fingers, or
rise like solitary stumps from
the bottoms of the channels.
The following are plans of
some of them.

Fie. 103. Plan of a part of the west edge of Inasmuch as these grow-
Lixa reef. ing portions of the reef are
in the deep channels that traverse it, the channels themselves vary
greatly in outlines — width and depth. Some of the measurements
may here be given: _
FY Channel 300 metres wide,
LLG) 8 metres deep at low tide;
, a few isolated coral masses
rising from the bottom.

Channel 80 metres wide,
3 metres deep.

Channel 85 metres wide,
8 metres deep; with
chapeirao.

Channel 65 metres wide, 9 metres deep; chapeiroes at the margins.
The bottoms of these channels are as nearly flat as may be ; the depth
measurements next to the walls are but little different from those in the
middle.

The anchor always brings up from the bottom blue calcareous mud ;

reef. Low tide.

BRANNER: THE STONE REEFS OF BRAZIL. 255

about the edges of the reefs also, wherever there are accumulations of
sediments they are in the form of calcareous mud that is blue a few
centimetres below the surface, but cream-colored to yellow and buff on
the surface.

The chapeiroes or isolated masses are at various depths beneath the
water ; some of them even reach the surface at low tide. Those whose
summits are uncovered at low tide have very flat tops. Their sizes and
forms in plan are simply endless. In some places they are so abundant
that they are only from one to six metres apart, and pretty evenly spaced ;
again they are but sparsely scattered over large areas.

It is on these growing isolated masses that the best examples of coral
heads are found. I was rather disappointed, however, in the corals of
the Lixa reefs. Really fine examples can be had here only at the lowest
spring tides. The biggest heads accessible were not more than from
forty-five to sixty centimetres in diameter.

The facts that most impress one in regard to the Parcel das Paredes
reef are (1) that the upper portion of it is completed and dead, (2) that
its growth is now confined to filling in the channels that separate its
larger portions, and (3), that the final completion of the still growing
portions consists in the extension of the isolated stumps until the spaces
between them are closed. In many places these stumps are so thick
that the reef may be said to be in its last stages of growth.

The reef is weaker in its development on the landward side than from
the centre eastward, and its landward side is about a metre lower than
the highest parts. The smoothness of the surface of these reefs as
compared with the reefs of the northern coast is remarkable. And
this smoothness is noticeable in all the reefs seen from Cabral Bay
southward.

As a place for collecting corals the Parcel das Paredes is no better
than scores of more accessible reefs along the coast of Pernambuco and
Alagéas. It has the advantage of not having been so much explored by
lime-burners as many of the northern reefs, but it has the disadvantage
of being a long way from land, with inconvenient sand-bars between the
land and the reefs.

An elevation of eight metres would kill nearly all of the living parts
of the Paredes reefs, but an elevation of two metres would not affect
them seriously.

I was told by a pilot who has lived at the Barra de Caravellas for forty
years, that the currents inside of the Abrolhos and Parcel das Paredes
reefs set strongest to the southwest in May, June, and July, that they

256 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

run in the same direction at other times of the year, but not so
strongly.’

Corda Vermelha, also called ‘‘Sebastiao Gomes,” a small island off
Vicosa, south latitude 18°, is a coral reef. The reef is quite flat, and is
entirely covered by water at high tide. The margins are said to have
steep, almost wall-like faces.? Some five or six years ago a Rio company
shipped the reef rock from Corda Vermelha to Rio de Janeiro, where it
was burned for lime.

The Abrolhos reefs. —The Abrolhos reefs I have not visited. It was
not possible to make an extensive study of them, and a visit of a day
during my stay at Caravellas hardly seemed worth while.

Reclus speaks of the coral reefs of the Abrolhos as the most remark-
able of this part of the coast ; but as coral reefs, in size and interest
they are hardly comparable with the Parcel das Paredes. He also says
the Abrolhos are “ trois ilots granitiques,” ? which they certainly are not,
though there is a sheet of olivine gabbro diabase overlying the sedi-
mentary beds upon and about which the coral reefs grow.

In order to make these notes as comprehensive as possible, I add here
what Hartt has written about the Abrolhos reefs.4

“ The islands of the Abrolhos lie about midway between the cities of Rio and
Bahia, a little south of the parallel of Caravellas, and at a distance of about
forty miles from the mainland. The position of the lighthouse on the island
of Santa Barbara is, according to Mouchez, latitude 17° 57’ 31” south, longi-
tude 40° 58’ 58” west from Paris. These islands are situated apparently near
the middle of the submerged border of the continent, which here, over a very
large area, lies at a depth of less than one hundred feet. They are four in
number, with two little islets, and they are arranged in an irregular circle,
three of them close together. All are rocky and rather high, Santa Barbara,
the principal one, being 33.22 metres in height. The length of this island is
about three quarters of a mile. Its outline is irregular, and it is very narrow.
It is composed of beds of sandstone, shales, and trap, which dip approximately
north-northwest, at an angle of from ten to fifteen degrees. Owing to this
northward dip of the strata, the northern side of this island presents a steep
slope to the sea, while on all other sides it is precipitous. The island is almost
divided in two in the middle, by a cove indenting it on thesouthern side. . . .

1 For further details and determinations of corals collected on these reefs, see
Hartt’s Geology and physical geography of Brazil, p. 203-211. :

2 Capitao Tenente Collatino Marques de Souza, Revista do Instituto Geographico
da Bahia, 1895, II., p. 27-29.

3 Nouvelle Géographie Universelle, XIX. Amérique du Sud, p. 268. Paris, 1894.

4 Ch. F. Hartt. Geology and physical geography of Brazil, p. 174-200.
Boston, 1870.

a

BRANNER: THE STONE REEFS OF BRAZIL. 257

“Tn lithological characters the Abrolhos beds resemble the sandstones, etc.,
of the Rio Sao Francisco at Penedo, . . . and which contain similar plant
remains. They have been disturbed by the same upheaval, and I have little
hesitation in referring both to the cretaceous. . . .

“‘ As we go northward from Cape Frio, the madreporians become quite com-
mon on the rocky shores, though the species are not numerous, and they are
associated with species of Mullepora, Zoanthus, and Palythoa, and various gor-
gonians. I have already called attention to the coral fauna of Guarapary and
Victoria, and I have stated that I have no evidence of the existence of any
banks of living corals or reefs south of the region of the Abrolhos. Here the
conditions for the growth of coral reefs on a large scale are remarkably favor-
able. Over large areas the water covering the great submarine shelf, on which
the islands are based, is much under one hundred feet in depth, and it is
warm and pure. So it is not to be wondered at that very large coral reefs,
both fringing and barrier, are found here.

** When the tide goes out there is seen extending round about one half the
circumference of the island of Santa Barbara a fringing reef. . . . One may
then walk out on its level surface as on a wharf, and from its ragged edge
look straight down through the limpid green water and see the sides of the
reef and the sea bottom covered with huge whitish coral-heads, together with
a wealth of curious things not to be obtained without a dredge.

“The surface of the reef, though flat, is somewhat irregular. It rises but a
short distance above low-water mark, and it is overgrown with barnacles,
shells, mussels, and serpula-tubes, together with large slimy patches of the
common leather-colored Pulythoa. The reef abounds in small pools, some
shallow and sandy, others deep, rocky and irregular. The former often con-
tained scattered masses of corals, particularly Siderastraea and Favia, and they
abound in small shells, crabs, Ophiurae, etc.; but the deep pools are the
richest in life. These are usually heavily draped on the sides with brilliantly
tinted sea-weeds and corallines, the bare rock being gay with bryozoa and
hydroids. The most common coral of these pools is Siderastraea stellata
Vermllie : %

“The material composing the reef is an exceedingly hard, whitish limestone,
ringing under the hammer, and, so far as I had an opportunity to examine it,
for the Brazilian reefs are never broken up by the surf, —showing no distinct
trace of organic structure. The Santa Barbara reef extends around about one
third of the island, and on the northwestern side it reaches across to the
‘Cemetery,’ so that when the tide is down that islet is joined to the main
island by a broad, level platform of rock, diversified by tide-pools, and form-
ing an excellent collecting-ground for the naturalist. The reef, built up prin-
cipally of Acanthastraea, Siderastraea, etc., has completed its growth on arriving
at low-tide level, the upper surface being still farther added to by serpulae,
bryozoa, corallines, barnacles, etc., together with the coral-sand and debris of
shells accumulating on the reef.

“So far I have spoken only of fringing reefs, but there are other coral

VOL. XLIV. 17

258 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

structures of greater interest in these waters. Corals grow over the bottom
in small patches in the open sea, and, without spreading much, often rise to a
height of forty to fifty or more feet, like towers, and sometimes attain the
level of low water, forming what are called on the Brazilian coast chapeirées.
At the top these are usually very irregular, and sometimes spread out like
mushrooms, or, as the fishermen say, like umbrellas. Some of these chapeirdes
are only a few feet in diameter. A few miles to the eastward of the Abrolhos
is an area with a length of nine to ten, and in some places a breadth of four
miles, over which these structures grow very abundantly, forming the well-
known Parcel dos Abrolhos, on which so many vessels have been wrecked. _

‘*T visited in my launch the northwestern part of this reef, where the
chapeiroes were sufficiently scattered to allow me to sail about among them.

“* Among these chapeirdes I measured a depth of sixteen to twenty metres,
and once, while becalmed, I found twenty metres alongside one chapeirao and
three metres on top. The chapeirdes, as a general thing, are rarely ever laid
bare by the tide. They are here, as elsewhere, of all heights and dimensions ;
but in no case do they reach low-water level, nor according to the testimony of
the fishermen and whalers, are they ever in any part uncovered. They do
not coalesce here to form large reefs as they do to the west of the islands.
When the weather is clear and cloudless, and the water calm, these chapeirées
can be readily distinguished at a considerable distance. The surface of the sea
appears to be flecked by shadows from a sky full of scattered cloudlets, pro-
ducing a striking effect. The water, being shallow and clear, and with a
sandy bottom, is of a very light greenish tinge, like that of the Niagara River
at Buffalo, The general color of the chapeirées is brown, from their being
encrusted with patches of Palythoa, and their position is marked by brownish
spots on the surface of the sea. In the daytime a launch may sail in safety
among them in calm weather, and a small vessel may traverse some of the
chapeirao grounds without danger, but large ships are likely to find themselves
in a labyrinth from which escape is not easy. In windy weather the waves
break over the chapeirées, but if there are white caps beside, and a cloudy sky,
their position cannot be made out, and it is safest to keep well away from
them.”

The corals collected on these reefs by Hartt are described by Verrill.*
The list is given below.

List or Corats CoLLecteD By C. F. Hartt on THE ABROLHOS REEFS.

Crass, POLYPI.

OrpER, MADREPORARIA.
Agaricia agaricites ? M. Edw. and Haime.
Siderastraea stellata Verrill, var. conferta Verrill.
1 A. F. Verrill. Notice of the corals and echinoderms collected by Prof. C. F.
Hartt, at the Abrolhos reefs. . . . Trans. Conn. Acad. Arts Sci., 1868, I., p. 351-364,
Pl, TV;

= —— ee eT

bo
Ou
Ne)

BRANNER: THE STONE REEFS OF BRAZIL.

Pectinia braziliensis M. Edw. and Haime.
Favia leptophylla Verrill.

Favia gravida Verrill.

Favia conferta Verrill.

Acanthastraea braziliensis Verrill.
Heliastraea aperta Verrill. °

Mussa harttic Verrill.

Symphyllia hartti Verrill.

Porites solida Verrill.

OrperR, ALCYONARIA.

Hymenogorgia quercifolia M. Edw. and Haime.
Gorgonia (Pterogorgia) gracilis Verrill.
Eunicea humilis M. Edw. and Haime.
Plecaurella dichotoma Kolliker.

Plexaurella anceps ? Kélliker.

Ciass, ACALEPHAE.
Orper, HYDROIDEA.

Millepora nitida Verrill.

Mullepora brasiliensis Verrill.

Millepora aleicornis Linn., var. cellulosa Verrill.

Millepora aleicornis Linn., var, digitata (?) Esper.
Millepora aleicornis Linn., var. fenestrata Duch. and Mich.

Thickness of the coral reefs of Brazil. — Near the rocky shores one can
frequently see the thickness of the coral reefs, but these places do not
help us to judge of the thickness of the same reefs a kilometre or two
out at sea. It is evident from the physical conditions controlling the
growth of coral reefs and from the shape of the submarine floor that the
Brazilian reefs grow in the shallow waters along and upon the continental
Shelf. It is not perfectly clear, however, whether this shelf may or may
not have been built up in places from great depths by an upward growth
of the reefs during periods of coastal depression. The contour of the
bottom on which the reefs started was not necessarily alike in all places,
so that there is a chance for some local variation in the thickness of the
same reefs, quite aside from any thickness attributable to the subsidence
of the coast along which they grow. It is evident, however, that since
Miocene times there has been an elevation of the coast that lifted the
marine Tertiary sediments out of the water and subjected them to ero-
sion both over the land surfaces and along the coast-line. Marine

260 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

erosion has vigorously encroached upon the land since the elevation of
the Tertiary beds, but it has always left a shallow shelf offshore. Then
followed a depression which carried beneath the sea some of the valleys
near the coast. Many low coastal islands were probably formed by this
depression, but most of these islands have long since been removed by
marine erosion. In this way it is believed that the Abrolhos islands
were separated from the Brazilian mainland. Those islands are low, and
the same Tertiary (%) sediments that form them lap back over the erys-
talline rocks of the mainland to an elevation of one hundred and fifty
metres. The distribution of the Tertiary rocks along the coast of Brazil
leads to the supposition that the valley that lay between the present
Abrolhos islands and the mainland was a broad shallow one. I say
shallow because all the valleys known in the coast Tertiary are shallow,
— less than one hundred metres deep.

The conclusion seems warranted, therefore, that any coral reefs that
may have taken possession of this submerged valley since its depression
are necessarily of limited thickness, probably not exceeding one hundred
or two hundred metres.

Since Pliocene times there has been a slight elevation of the land, but
the coral reefs do not seem to have been near enough to the surface at
the time of the elevation to have been lifted altogether out of the water
by it. At least no reefs are now known along the Brazilian coast stand-
ing quite out of the reach of tide-water. There are several places at
which there are dead coral reefs, but for aught that is now known they
are dead only because they have reached the upward limits of coral
growth. There are also some dead corals to be found among the debris
of the elevated beaches of Bahia, but thus far no solid coral reefs have
been found among these shell heaps.

The coral rock that rises. above the reef and above tide-water at_
Maceio is not the remains of an elevated and eroded reef, but the up-
lifted corner of a piece of reef rock that has been undermined by the
tidal currents.

In this particular case the thickness of the coral reef appears to be
exhibited by the edge of the up-tipped block. It seems to show that
the coral reef at this particular place is very thin and rests upon a base
of soft material that the marine currents have been able to excavate.

The profile of the coast in the vicinity of many of the coral reefs also
suggests that the reefs must be quite thin. Reference is here made to
those places in which the reefs lie near a coast having steep bluffs facing
the sea — such as exist along the greater part of the coast. The profile at

BRANNER: THE STONE REEFS OF BRAZIL. 261

Rio Formoso, Maceio, and Tamandaré may be taken as the type of this kind
of geographic relations of the reefs. The reefs in such places are usually
long and slender, and it is believed that they are younger than the large
reefs. These forms are so constant that one profile can be substituted
for another without modification of any of the essential features. In the
cases of the largest reefs, such as. those of Cape Sao Roque reefs, the
Parcel das Paredes and the Abrolhos reefs, the adjoining coasts are low,
and the coral reefs are probably older and thicker than they are off the
steep shores of the coast of Pernambuco and Alagéas.

In at least one instance it seems probable that the coral reef (that at
Parahyba do Norte) has taken possession of and is now growing upon a
submerged stone reef. Briefly stated, the reasons for this opinion are : —

I. A deep well sunk at Cabedello inside the reef penetrated only the
soft coastal sands.

II. The reef lies across the ancient mouth of the Rio Parahyba do
Norte, —the position in which the stone reefs of the coast are usually
formed.

The coral reef could live in its present position, however, only after
the formation of the Ponta da Matta spit, which turned the river waters
away from the reef. The coral of the Parahyba reef is probably less
than five metres in thickness.

The actual thickness of the reefs can, in my opinion, be ascertained
with absolute certainty in but one way, and that is, by boring into the
reefs at a large number of places. Some idea of their thickness can be
had, however, by working out the geological and geographical history of
the coast. The first method it has not been convenient to employ ; the
second one has been made use of in the present paper in so far as it has
been possible to make out the coast history. We must conclude, there-
fore, that the coral reefs of the Brazilian coast probably nowhere exceed
a thickness of one hundred metres. Most of them are much thinner
and do not exceed fifty metres. The greater part of them are even
thinner than this.

The age of the coral reefs. — The existing coral reefs are necessarily de-
scended from the ancient ones. But the geologic and geographic history
of the Brazilian coast cannot be traced with much precision further back
than Tertiary times.

Magnesian limestones and dolomites found among the Cretaceous
rocks of Sergipe and in the Cretaceous (or Tertiary ?) rocks of Pernam-
buco, and Rio Grande do Norte show that coral reefs existed on this
coast in Cretaceous times ani the present reefs must be descended from

bo

262 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

those of Cretaceous age. In the rocks known to be of Tertiary age there
is but little evidence of the existence of coral reefs. The geographic de-
velopment of the coast, however, and the distribution of the reefs at the
present time lead to the inference that the reefs, as they are now known,
began their existence after the elevation and erosion of the Eocene Ter-
tiary beds along the Brazilian coast. This is suggested, if it is not
proved, by the fact that the present reefs grow upon the marine shelf
cut by the sea in the Tertiary and older rocks, or they occupy areas that
were submerged after the erosion of the Eocene beds had been in process
for a considerable period. There has been much encroachment upon the
land by the sea, and this encroachment has been followed up sharply by
corals taking possession of the submarine shelves wherever the conditions
were favorable until we now have coral reefs growing close to the sea
bluffs. The reefs at and about the Abrolhos group are built upon sub-
merged Tertiary rocks. They therefore began in the latter part of the
Tertiary and have continued down to the present time. This seems to
be true of all the large reefs: those of the Abrolhos, Parcel] das Paredes,
and those at Cape Sao Roque; and these reefs are not only the largest,
but likewise the oldest and probably the thickest of the reefs of the
Brazilian coast. Many of these reefs, however, long ago finished their
upward growth and are now growing only laterally.

For reasons already given the barrier and fringing reefs that grow
near the steep shores appear to be newer than the large offshore reefs.
No line of demarcation, however, can be drawn between the large off-
shore reefs and the near-shore barrier and fringing reefs. They all
merge together both in physical characters, in thickness, and in age.

The coral reefs, therefore, antedate the stone reefs. ‘This is shown by
the occurrence of reef-building corals in the rocks of the stone reefs, and
aiso by the relative positions of the two kinds of reefs, along the coasts.
The coral reefs are also locally newer than the stone reefs, as is shown by
the former growing upon the latter. The corals will continue to grow
seaward from the stone reefs, while the latter will change but little. No
elevated coral reefs are now known on the coast of Brazil. If the eleva-
tions of Pliocene times ‘killed some of the reefs, they were again taken
possession of and new reefs grew upon the old ones as soon as they were
resubmerged.

The Brazilian coral reefs are almost everywhere narrow. The wid-
est are those of the Abrolhos, Parcel das Paredes, Itassepanema, Ita-
columis and Cape St. Roque, which are at most only about thirty-three
kilometres wide. Some of the coral reefs connect with the land and

BRANNER: THE STONE REEFS OF BRAZIL. 263

would therefore be regarded as fringing reefs. This relation has usually
been brought about, however, by small geographic changes, such as the
drifting of the shore sands behind the outer reefs. The channel between
the coral reefs and the shore is deepest between the Abrolhos and the
Parcel das Paredes. It is there only eleven fathoms. For the most part
the depth is considerably less, and too small to admit the entry of ordi-
nary sailing vessels.

With the exceptions noted below the coral reefs of Brazil have no
apparent connection with eruptive phenomena. There are probably in-
cipient reefs about the volcanic island of Fernando de Noronha, and it is
possible or even probable that the Rocas reefs are built upon an erup-
tive base. But the Rocas reef is two hundred and twenty-four kilo-
metres from the Brazilian mainland, with a channel of over two thousand
fathoms separating it from the barrier reefs of the coast. The island of
Santo Aleixo, just south of Cape Santo Agostinho, is likewise eruptive,
but it is only two or three kilometres from the shore, and therefore has
no relation with the coral reefs other than that of the sedimentary rocks
along the same coast. There are igneous rocks also in the Abrolhos
Islands, but they are sheets and dikes in the rocks that form the group.

THE CHemicaL Composition OF THE Brazinian Corats.

I have had analyses made of a few of the skeletons of living corals
the results of which are given in table (A) on page 264.

All samples were washed with boiling distilled water to remove sea
salt, and the complete removal was verified. The washed samples were
dried, and of these the analyses were made. All the Specimens contained
considerable organic matter.

It should be noted that these analyses are of skeletons of polyps, the
upper portions of which were living when the samples were collected,
Samples were also taken of the dead reef rock at Ponta do Mangue,
State of Alagéas, one hundred kilometres northeast of Maceio, and of
this rock an analysis has been made with the results as given in table (B)
on the next page.

If all the calcium present were there as carbonate, and the rest of the
carbon dioxide as magnesium carbonate, it would be equivalent to

Carbonate of lime (ORC O Ee BRIG
Carbonate of magnesium (MgCO,) . . . 12.98

It should be especially noted that the specimens of the reef rock rep-
resented by the last analyses were taken from an old reef that has long
been dead,

264 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY.

(A.) ANALYSES OF BRAZILIAN CORALS.
L. R. Lenox, Analyst.

u II. III. LV. a VI.
= beg = = = 3 2
8.2 eS 3 = ee 25
ry 3 a)
Founp. gs 223 se te Ss | 4 g
ne SER a S's La ss
Se | 8Se [> See) Seas Seer
Se [ea [S| bole jes
ae > q = | S83
Silica (SiO,) 05 03 12 05 08 03
Oxides of Iron and Alumina
(Al,O3, Fe Qs). 07 09 .20 22 .08 07
Lime (CaO) 54.41 | 54.29 | 54.13 | 52.38 | 54.80 | 53.41
Magnesia (MgO) 24 .20 .26 .25 21 99
Sulphuric acid (SOs) 52 4 | not not not 1.56
deter. | deter. | deter
PROBABLE COMBINATIONS.
Silica (SiO) 05 03 12 05 .08 03
Oxides of Iron and Alumina
(Al,03, Fe.O3) 07 09 .20 22 .08 07
Calcium carbonate (CaCOs) 96.52 | 96.28 | 96.66 | 93.44 | 96.96 | 93.80
Magnesium carbonate (MgCO3) 50 42 54 52 44 |} 2.08
Calcium sulphate 88 91 | not not not 2.14
deter. | deter. | deter
Organic matter, Sodium chlo-| not not not not not not
ride deter. | deter. | deter. | deter. | deter. | deter.
Totals .. « . «© «= | 98.02) [901s | 19TS2 POR SaieG Ebon Ossie,

(B.) ANALYsIs OF THE REEF Rock oF Ponta Do ManaueE,
SraTE OF ALAGOAS, BRAZIL.

R. E. Swain, analyst.

No. 1. No. 2.
Calcium oxide (CaO). 7) &) See 46.08
Magnesia (MgO) . . - . - - =. 6.95 7.05
iron (Fe,0,) >. =*«_ =)°- 0) oe 0.88
Alumina (AJ,0,)... =.» 2-5 5) = ep ee 0.59
Sodium (Na) . . MA Merit ee) oe trace
Carbon dioxide (CO,) MM ath 42.96
Silica (Si0,) . . i wh) Gea 1.29
Phosphoric anhy Aside @, 05) + tapas Ae 0.26
Chlorine@@l) .. .; ee _ 0.28
Water (HO) °.( 0.0 8 0.77

TOTAL 272) eee 99.95 100.11

BRANNER: THE STONE REEFS OF BRAZIL. 265

The chief interest in these analyses lies in the difference in magnesium
contents between the rock of the living coral and the old coral rock :
excepting the Millepora none of the living corals contain more than a
half of one per cent of magnesium carbonate, while the old rock con-
tains nearly 13 per cent.

Evidently coral polyps secrete pure lime carbonate skeletons, and when
a coral reef stands for a long period saturated with sea water, some of the
lime of the coral mass is replaced by magnesium from the sea water, and
a dolomite, or dolomitic limestone, is thus eventually produced.

It seems evident also that this process of dolomitization could only
take place beneath the sea where magnesium water is available, and in
material sufficiently porous to permit some circulation of sea water.

Since these results were obtained I have found that as long ago as
1846 Dana had analyses made of the skeletons of living corals, and that
very little magnesia was found in them.

In 1852 he reported an analysis by Silliman of “the coral limestone
of the elevated coral island Matea”’ in which 38.07 per cent of carbonate
of magnesia was found. These facts led Dana to infer that the lime
carbonate had been replaced by magnesia.”

The results obtained from the Brazilian reefs agree very closely with
those obtained by Dana for the Pacific corals except that the analysis of
the older Brazilian coral rock was made of a rock still within the reach
of the sea water, and in which dolomitization was apparently in process,
while the analysis of the Pacific coral rock was made from materials far
beyond the reach of the sea and in which dolomitization had evidently
proceeded much further.

Another matter of interest in connection with the old reef rock is that
the structure of the mass seems to be disappearing in proportion as the
dolomitization takes place. In the fresh materials there is no difficulty
in determining the forms of the organisms that have produced the rock,
while the structure of the old reef rock is much obscured, and most of
the organisms quite impossible of identification.

1 On the chemical composition of the calcareous corals. By B. Silliman, Jr.
Amer. Journ. Sci., ser. 2, 1846, Vol. I., p. 189-199.

2 James D. Dana. On coral reefs and islands. Amer. Journ. Sci., ser. 2, 1852,
XIV, p. 82.

266 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

r List OF THE CORALS OF THE Coast OF BRAZIL.

The following list is made up from the observations of the author and
from all the known lists and descriptions of Brazilian reef corals. Follow-
ing the name of each locality are given in parentheses the names of the
authorities or collectors. Two other species are mentioned as having been
found at the Lagda de Camamii by Spix and Martius, but it has not been
possible to identify them. The list does not include the deep-sea corals
dredged off the coast by the “ Challenger”? and other expeditions.

Most of the identifications have been made by Dr. Greeley, who was
kindly assisted in doubtful cases by Dr. T. W. Vaughan. Professor
Verrill’s paper on Brazilian corals, published in the Transactions of the
Connecticut Academy of Science, XI., was not seen until after this re-
port was in type. That paper contains several varieties not mentioned
in this list. It has not been possible to revise the list since seeing the
paper of Professor Verrill.

Crass ANTHOZOA.

1. Astrangia solitaria (7?) Milne Edwards and Haime.?
2. Phyllangia americana Milne Edwards and Haime.

These two forms were found on the sandstone reefs north of Pernam-
buco. The Astrangia was also found by Von Ihering at Bahia and at
Sao Sebastiao, State of Sao Paulo, and by Branner at Caravellas.

3. Heliastraea (Orbicella) aperta Verrill.

Trans. Conn. Acad., Vol. I. part 2, page 356. Maceio coral reef

(Greeley). Itaparica (Rathbun). Abrolhos (Hartt).
4. Heliastraea (Orbicella) acropora Linn,

Bahia de Camamu (Spix and Martius).

5. Heliastraea (Orbicella) cavernosa Milne Edwards and Haime.

Lagéa de Camamu, Bahia (Spix and Martius). It was also dredged
in 30 fathoms off Barra Grande, Brazil. This is a West Indies species
of reef coral. The station at which it was found is at about west
longitude 34° 49’, south latitude 9° 7’, near the edge of the 100 fathom
line.8

1 John J. Quelch. Report on the reef-corals collected by H. M.S. “ Challenger”
during the years 1873-1876. “Challenger” Reports, Zodlogy, Vol. XVI.; Th.
Studer. Supplementary report on the Aleyonaria, Vol. XXXII., London, 1889.

2 Dr. Vaughan says there are three species of Astrangidae on the coast of Bra-
zil: Astrangia, similar to A. solitaria (Les.) Ver. 1864; a new species, A. Rathbuni
Vaughan MS.; and Phyllangia americana Milne Edw. and Haime. (Porto Rican
Corals, p. 299.)

® “Challenger” Reports, Zodlogy, XVI., 18.

10.

itilé

12.

13.

14,

15.

16.

1%.

Sci

BRANNER: THE STONE REEFS OF BRAZIL, 267

Favia gravida Verrill.

Trans. Conn. Acad., Vol. I., part 2, page 355. Rio Grande do Norte
sandstone reef, Cape Bacopary, Mamanguape, Goyanna (Greeley). Per-
nambuco sandstone reef (Hartt). Maceio coral reef (Greeley). Abrol-
hos and Cape Frio (Hartt). Itaparica (Rathbun). Rio Formoso,
Tamandaré, Santo Aleixo, Parcel das Paredes (Branner).

Favia conferta Verrill.
Fernando de Noronha (Branner).!
Favia ananas Lamk.

Fernando de Noronha (Ridley).

Favia deformata Milne Edwards and Haime.

Fernando de Noronha (Ridley).

Mussa harttii Verrill.

Trans. Conn. Acad., Vol. I., part 2, page 357. Maceio coral reef
(Greeley). Abrolhos (Hartt). Candeias (Hartt). Rio Formoso, Parcel
das Paredes (Branner). Itaparica (Rathbun).

Mussa verrillit Rathbun.
Fernando de Noronha (Branner).
Symphyllia hartti Verrill.

Trans. Conn. Acad., Vol. I., part 2, page 358. Maceio coral reef
(Greeley). Abrolhos and Lixa reefs (Hartt). Sto Sebastiio, State of
S. Paulo (H. Von Ihering). Itaparica (Rathbun).

Dichocoenia wva Milne Edwards and Haime.

Bahia de Camamu (Spix and Martius).

Pectinia brasiliensis Milne Edwards and Haime.

Water-worn specimens were found by Mr. Branner at several places
along the beach between Rio Manguaba and Rio Camaragibe. It was
also found at Bahia by Dr. Von Ihering.

Agaricia agaricites ? Milne Edwards and Haime.
Maceio coral reef (Greeley). Abrolhos (Hartt). Parcel das Paredes,
Santo Aleixo, Rio Formoso (Branner).
Siderastraea stellata Verrill.
Itaparica (Rathbun). Santo Aleixo (Branner).
Porites verrilli Rehberg.

Trans. Conn. Acad., Vol. I., part 2, page 358, as P. solida. Rio Grande
do Norte sandstone reef, Cape Bacopary, Mamanguape, Goyanna
(Greeley). Pernambuco sandstone reefs (Hartt, Branner). Maceio coral
reef (Greeley). Abrolhos and Lixa reefs (Hartt). Candeias (Hartt).
Tamandaré, Rio Formoso, Maria Farinha, Parahyba do Norte
(Branner).

1 In Verrill’s late paper on Brazilian corals, published in the Trans. Conn. Acad.
., XI., Maeandra conferta is reported to have been collected at Fernando de No-

ronha by Hartt. The corals sent Verrill from Fernando were collected by the
writer in 1876. Hartt never visited that island.

268 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

18. Porites branneri Rathbun.

2 Proc. U. S. Nat. Mus., Vol. X., 1887, p. 355-356. Parahyba do
Norte (Branner). Candeias (Hartt). Rio Grande do Norte sandstone
reef, Maceio coral reef (Greeley).

19. Gorgonia quercifolia Milne Edwards and Haime.
Fernando de Noronha (Branner).

20. Gorgonia, sp. ?
Fernando de Noronha (Branner).

21. Hymenogorgia quercifolia Milne Edwards and Haime.
Cape Frio to Pernambuco (Hartt).

22. Eunicea humilis Milne Edwards and Haime.
Abrolhos, Porto Seguro (Hartt).

23. Eunicea sulphurea Ehr.
Parahyba do Norte (Branner).

24. Eunicia castelnaudi Milne Edwards and Haime.
Bahia (Castlenau).

25. Plexaurella dicholoma Koll.
Abrolhos (Hartt). Rio Formoso, Parahyba do Norte (Branner).

26. Plexaurella anceps ? Koll.
Abrolhos (Hartt).

Crass HYDROZOA.
27. Millepora braziliensis Verrill.
Trans. Conn. Acad., Vol. I., part 2, page 363. Maceio coral reef
(Hartt, Greeley). Abrolhos and Pernambuco (Hartt). Itaparica
(Rathbun). Fernando de Noronha, Rio Formoso, Parahyba do Norte,
Parcel das Paredes (Branner).
28. Millepora alcicornis Linn.
Trans. Conn. Acad., Vol. I., part 2, page 363. Candeias (Hartt).
Pernambuco sandstone reef (Hartt). Maceio (Greeley). Bahia (Von
Ihering). Rio Formoso (Branner).

Notes ON THE CORALS COLLECTED ON THE NortTHEast Coast OF
Brazit. — By Arthur W. Greeley.

The corals collected by the expedition along the coast of Brazil in
June and July of 1899 may be divided into two groups, — first, those
taken on the sandstone reefs along the northern part of the coast from
Pernambuco to Natal, and second, the collection made on the coral reef
of Maceio, Alagdas. The collecting on the sandstone reefs was very
hastily done because of the large extent of coast-line to be covered, and
the few species of coral obtained do not represent all the corals to be
found on the stone reefs. Three weeks were spent on the Maceio reef,
however, and the collection is probably complete for that locality.

BRANNER: THE STONE REEFS OF BRAZIL. 269

On the sandstone reefs four species of corals were obtained, Porites
verrilli, Porites branneri, Favia gravida, and Millepora alcicornis. <A\-
though two of these, Porites verrilli and Favia gravida, are very common,
growing abundantly on every reef visited, the corals at no place form
any considerable part of the stone reefs, but exist only in small, isolated
masses. The other two species are not at all abundant, Porites branneri
being obtained only on the Rio Grande do Norte reef, and Millepora
alcicornis only at Pernambuco.

The outer edge of the sandstone reefs slopes gradually toward the sea,
and is everywhere cut up by the waves, forming pools and caverns that
are lined with encrusting anemones, ascidians, etc. It would seem
that these sheltered pools, continually washed as they are by the
fresh water of the outside of the reef, ought to afford splendid locations
for the growth of these corals. On the contrary, they do not grow here
at all, but are found chiefly on the inner edge of the reef, even in places
where the coral heads are nearly covered by the silt and sand that is
washed by the river currents against the inside of the reefs. Small
masses of coral are scattered over the top of the reefs in the shallow pools
that are always full of water, but the largest heads are always found
along the extreme inner edge. The abundant growths of encrusting
anemones and barnacles on the exposed portions of the sandstone afford
a considerable protection from the never-ceasing pounding of the waves,
but the corals scattered in small, isolated masses are of little or no im-
portance in the formation or preservation of these wonderful sandstone
reefs.

Porites verrilli is by far the hardiest and most abundant coral on this
part of the coast, and thrives wherever there is a suitable ledge of rock
upon which to grow. It forms remarkably round, even, perfect heads,
never attaining a greater size than a foot in diameter on the sandstone
reefs, and usually only a few inches. It was found commonly on all the
reefs visited, and its hardiness is well shown by the apparent ease with
which it adapts itself to all sorts of unfavorable conditions, growing high
up on the reef, sometimes entirely exposed at low tide, and sometimes
buried in the mud on the inside of the reef. The rock of this species is
remarkably solid and firm, and is much thicker and more lasting than
that of any other species.

Growing with Porites verrilli, though not so common, is Favia gravida.
These two species form nine tenths of all the coral life on the sand-
stone reefs, and follow each other in distribution, although Favia gravida
is not so hardy, and does not thrive so well in the muddy water along the

270 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

inside of the reef. Its heads are very small, rarely more than two or
three inches in diameter, and not more than an inch or so in thickness.
This species varies considerably in the character of the walls between the
cells. Typically they are thin and ungrooved, but in a few small speci-
mens from the Mamanguape and Rio Grande do Norte reefs the walls
were thick and decidedly concave.

Porites branneri is a rare coral and was found by the expedition only
on the Rio Grande do Norte stone reef at Natal. One large head six
inches in diameter, bluntly conical in shape and irregularly lobed, was
collected. It is of a deep brown color in life. The cells resemble very
much those of Porites verrilli in form, but they are smaller, and the
texture of the rock is much more porous.

Millepora alcicornis was the only Millepore found on the sandstone
reefs, and this one was observed in only one place, between two portions
of the Pernambuco reef in about three feet of water at low tide. It
formed here a clump a foot or so high, with a few smaller masses grow-
ing about it.

The Maceio coral reef. — The only true coral reef visited by the writer
was the Maceio reef (see Fig. 94, p. 166), located about one hundred and
fifty miles south of Pernambuco, off the town of Maceio, State of Alagéas.
The reef is a splendid example of the great barrier reefs found along the
Brazilian coast. The corals are very abundant, growing actively along
the outer edge, and because of its easy accessibility from the shore, the
reef is a good one for study. It is about three miles long, fully two
thirds of a mile wide at its broadest part, and the whole of its upper sur-
face is exposed at the lowest tides of each month. The reef is broadest at
its northern end, where it joins a small point that forms the northern
boundary of the Bay of Maceio. Here the reef is very firm and even,
and it is possible to walk outward over two thirds of a mile of solid coral
rock almost without any breaks. This part of the reef is apparently the
oldest, and contains very few growing corals. From this point the reef
runs nearly south at a distance of about half a mile from the shore, and
becomes very irregular at the lower end, forming several small fragments
of coral rock, one lying inside the other. This broken part of the reef
abounds in growing corals along the narrow channels between the differ-
ent sections of the reef, and the rock is much less solid, containing many
pools and caverns that communicate with the outside, and all these
channels are covered with corals of one kind or another. The coral rock
formed at first is extremely irregular, existing in narrow ridges and
ledges enclosing these hollow spaces in the reef; but as the growth con-

BRANNER: THE STONE REEFS OF BRAZIL. Aid

tinues the firmer corals gradually fill up these spaces so that the inner
and older portions of the reef are comparatively smooth and solid. The
inner edge of the reef consists of a perpendicular wall not more than five
or six feet deep and usually much less, but the outer edge slopes gradu-
ally toward the sea for twenty feet or more, and then plunges directly
downward as a sheer wall to a depth of twenty-five or thirty feet. This
extreme outer edge at the top of the perpendicular wall is covered by two
feet of water at low tide, and it is here that the corals grow in the great-
est profusion along the whole face of the seaward wall and as high up as
the tides will allow.

Sand has been constantly accumulating inside the reef so that the inner
bay is not more than ten feet deep at any point. There are two or three
isolated portions of the reef in this bay that have been nearly covered up
by the sand and contain only dead coral rock.

The reef is everywhere covered by a solid layer of coralline rock.
This coralline follows the corals wherever they grow, extending right up
to the fleshy part of every coral head. On the older portions of the
reef it adds the upper smooth layer, several inches in thickness, that ce-
ments together the loose coral rock and makes it lasting. Its importance
as a protection to the reef can hardly be overestimated.

In some places there are elevated spots on the reef formed wholly of
encrusting masses of worm tubes. These exist often in the most exposed
positions, and form layers of great durability, although they are not of
much importance to the reef because of their limited growth. The ex-
treme outer edge of the reef where it is exposed to the full force of the
breakers is carpeted by small encrusting anemones that are remarkably |
tenacious in their hold on the rocks, and must save these portions of the
reef from much of the wear and tear of the waves. This part of the reef
is greatly eaten away, however, by the common rock-boring sea-urchin,
Echinometra subangularis, that is very abundant both here and on the
sandstone reefs.

The general surface of the whole reef is quite even, and is exposed
nearly two feet at extreme low tide. This exposed portion is composed
almost entirely of coralline rock and various encrusting layers of worm
tubes, etc. At several points near the northern and oldest part of the
reef, however, there is solid coral rock well above the low-water mark,
which seems to show that the oldest portions of the reef at least have
once been considerably higher than their present level. One of these
elevated portions consists of a solid mass of Millepore rock rising at
least eight feet above the general surface of the reef, and is exposed even

72 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

bo

at high tide. This mass of rock is shaped like a pyramid, fifteen feet
broad at the base, much honeycombed out by the waves.’ At another
part near by I found an extensive area of Porites rock nearly two feet
above the level of low tide.

Porites verrilli is at Maceio, as at every other place where we collected,
the most abundant coral, and is by far the most important structural
coral of the reef. It grows everywhere, even on the sand-covered inner
edges of the reef, where no other coral can live except Favia conferta.
Notwithstanding the abundance of this species, it grows only in small
isolated heads, and in no place could I find large masses of Porites
growing in such a way as to form any considerable addition to the reef.
At one time it must have grown in huge heads all over the reef, for the
older portions are nearly solid Porites rock, which can readily be seen
wherever the reef has been excavated for lime. So while the greater
part of the reef has been built up by this species in former times, for
some reason it has been crowded out of the growing part of the reef, and
is now scattered everywhere in small isolated masses with Pavia con-
ferta. This coral forms extremely solid and lasting rock, though it is
not so dense and durable as that of the Mvliepores, nor so hard and
tough as the rock of the Orbicella aperta.

Porites branneri was found in only one place, growing in small heads,
and appears to be rare here as elsewhere.

Favia gravida is scattered all over the reef with Porites verrilli in small
heads which form no thick layers of coral rock. Its distribution on this
coral reef agrees exactly with what was already*observed on the sand-
stone reefs.

Millepora alcicornis and Millepora braziliensis were found in great
numbers, and the former was, next to Porites verrilli, the most important
structural coral obtained, forming with the Porites the greater part of
the old reef. Millepora alcicornis lives on the extreme outer edge of
the reef in the heavy breakers where few other corals grow. In these
exposed places it thrives, growing either in huge erect clusters on sub-
merged bases of rock, or in overhanging masses many feet in extent on
the extreme outer edge of the main reef. In these the corals grow either
outward horizontally or downward from the under surface of these over-
hanging ledges. In these single clusters all variations from the bluntly
lobed to the slenderly pointed or fenestrated forms, until recently known
as distinct varieties, were found, showing clearly that these are all sim-
ply different phases of this highly variable species. Much of these

1 This is an uptilted block that has been undermined by the waves. See pages
160 and 161 of this report. —J. C. B.

BRANNER: THE STONE REEFS OF BRAZIL. aae

exposed ‘portions of the reef seems to be solid MWillepore rock, which is
certainly being constantly added to by the rapid growth of this species at
the present time. This Mvllepore rock is the most dense and durable of
all, though it is extremely brittle, and, because of its mode of growth, is
more easily broken than that of either Porites verrilli or Orbicella aperta.

Millepora braziliensis grows all over the reef, but in small, isolated
heads that add but little to the reef structure.

Orbicella aperta grows in regular heads that are sometimes two feet
or more in diameter, and with an even greater depth of clean, unbroken
rock, which is very tough and tenacious. This species would be a
very important structural coral if it were more abundant, but it grows
only in isolated masses which add comparatively little to the reef. It is
found in the more sheltered places of the outer edge of the reef, and
forms beautiful, conspicuous heads, because of the large cells and promi-
nence of the polyps that look very much like small, encrusting anem-
ones. The rock is porous but remarkably tough and durable.

Mussa harttit is the most striking coral of the Maceio reef. It com-
pletely lines the borders of the sheltered lagoons that are constantly
filled with the fresh water of the outside. It is a densely branching
species forming huge clumps of nearly a solid mass of short thick stems.
These clumps rise to a height of ten or fifteen feet in the sheltered coves,
but are usually only a foot or so high and as broad along the outer edge
of the reef. These smaller clusters grow in the greatest profusion wher-
ever the water is clear and the force of the waves is not too great. The
thick stems are white surmounted by polyps of a brilliant lavender hue,
that are extremely showy because of their large size and bright colors.
The stems are very fragile, however, and this species adds to the reef by
the accumulation of its broken fragments. After a time the clusters
become too heavy for the weak stems, and the waves play havoe with
the whole mass, scattering the branches all over the reef. Some of the
best collecting of the whole reef is to be had in these Mussa heads, which
harbor an immense variety of crustaceans, echinoderms, worms, etc.

Symphyllia harttii grows in the same locations as its near relative
Mussa harttii, and resembles it very strikingly in appearance. The color
and size of the polyps are about the same as those of Mussa, but Sym-
phyllia grows in low solid heads, while Mussa forms branching clusters.
Symphyllia is also very much less abundant than Mussa.t

1 Dr. T. W. Vaughan, to whom I am indebted for corrections in the nomencla-
ture, tells me that Symphyllia harttii is, as Verrill at first suspected, only a growth

form of Mussa harttii. J.C. B.
VOL. XLIV. 18

274 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

A species of Agaricia was found growing plentifully in the Mussa
clusters. The polyps are of a beautiful brownish-red color with green
centres.

This whole Maceio region is a very interesting one, and deserves more
thorough investigation. North of this main reef just described there
are many smaller patches of coral rock that may contain some of the
other Brazilian corals described from Bahia and the Abrolhos by Verrill
and Rathbun. If the collection described in this paper is complete, it is
a remarkable fact that the range of a number of the corals so common in
the south should end abruptly in the region of Bahia.

R&sumfé oF CoNcCLUSIONS REGARDING THE CoraL REEFs.

The coral reefs of Brazil extend along the coast from the Abrolhos
Islands in south latitude 18° nearly to the mouth of the Amazon River.
The reefs, however, are not continuous, but are broken by many and
large gaps. The only reefs well off the coast are on the Rocas Island in
south latitude 3° 51’, west longitude 33° 48’, and 225 kilometres from
the mainland. The reefs of the coast are both barrier and fringing reefs.
They are usually narrow, — from ten to fifty metres in width ; the widest
are the barrier reefs, some of which are about thirty kilometres in width.
Most of the near-shore reefs are quite thin, probably not exceeding a
thickness of ten metres; the reefs that grow further out are thicker, and
it is possible that some of the barrier reefs, like those of the Abrolhos
group and of the Cape St. Roque group, have a maximum thickness of a
hundred metres at their outer edges.

There were coral reefs on the Brazilian coast during Cretaceous times
and also during Eocene and Pliocene times. The coral reefs may, there-
fore, be regarded as having survived since the Pliocene, at least. The
reef corals are found both beneath and on top of the stone reefs with
which they are contemporaneous. It is highly probable that some of
the coral reefs of the coast grow upon and conceal stone reefs. The
coral reefs have no connection with eruptive phenomena, with the pos-
sible exception of those of the Rocas, which are two hundred and twenty-
five kilometres from the mainland.

Many of the Brazilian coral reefs, having reached the upward limit of
growth, are now dead and are growing only laterally. This is true of
both the large barrier reefs and of the fringing in-shore reefs.

The coral polyp fauna of Brazil contains twenty-eight known species.

BRANNER: THE STONE REEFS OF BRAZIL. 275

This fauna is more closely related to that of the West Indies than to any
other now known.

The dead coral reef rock is being changed to dolomite by the replace-
ment of a part of the calcium by magnesium from the sea water.

No recent coral reefs elevated above tide-level are known on the
coast of Brazil. There are, however, satisfactory evidences of a late ele-
vation of the coast amounting to about two metres. At many places
dead coral reefs are buried beneath sands and other mechanical accumu-
lations brought down from the land.

The coral reefs have been an important protective and constructive
factor in controlling the outlines of the Brazilian coast. Some of the
small harbors of the coast are formed by coral reefs: such are Maceio
and Tamandaré. The sand beaches and spits have also, under the pro-
tection of the reefs, extended themselves seaward, and even encroached
upon and buried some of the coral reefs themselves.

bo
bee |
for)

BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

XPLANATION OF THE PLATES.

PLATE 1.

Northeast coast of Brazil, showing the locations of stone and coral reefs and the
configuration of the ocean’s floor off the coast from Bahia to Aracati. See
page 183.

PLATE 2.

Map of the stone reef at Pernambuco, made by Harold Havens, July, 1899. See
page 60.

PLATE 3.
Santa Cruz Bay, part of Hydrographic Chart 484, with additions. See page 95.
PLATE 4.
Map of the Bay of Bahia: a part of Hydrographic Chart No. 1522. Most of the
soundings given on the original are omitted. See page 128.
PLATE 5.

Topographic map of the Brazilian coast about Santos, showing how the coastal
mountains have been submerged, leaving their peaks as islands or as hills in a
swampy region. (Reduced from the Sio Paulo sheet of the Commissaio Geo-
logica de S. Paulo.) See pages 128 and 129.

PLATE 6.

Part of Hydrographic Chart 481, showing the reefs at Cape St. Roque. See page
228. F

PLATE 7.

Part of the Hydrographic Chart of the mouth of the Rio Parahyba do Norte, show-
ing the coral reef and its relation to the coast. See page 232.

BRANNER: THE STONE REEFS OF BRAZIL. 277

PLATE 8.

The reefs from Santa Cruz to Comoxatiba, State of Bahia. From the Hydrographic
Chart ; with additions showing the stone and coral reefs. See page 251.

PLATE 9.

Part of the Hydrographic Chart, showing the Lixa, Parcel das Paredes, and
Abrolhos coral reefs. See pages 251-257.

PLATE 10.

Abrolhos Islands: a part of the Hydrographic Chart. The submarine contours are
drawn in from the soundings. See pages 256-258.

PLATE 11.

The Tertiary (?) cliffs at Barreira do Camaragibe, State of Alagdas. At the base
of the bluffs the rocks are buff and gray ; the same beds higher up are brightly
colored. Photograph taken from ledge exposed at low tide. See page 19.

PLATE 12.

Tertiary (7) sandstones and shales a mile south of Barreira do Camaragibe. The
upper parts of these beds are highly colored: the lower parts are of neutral
tints. See page 19.

PLATE 13.

The beach at Camaxo, on the coast of Alagéas, where the basal Tertiary (?) con-
glomerates contain large granite boulders. Looking S. 48° W. Sao Bento in
the distance.

PLATE 14.

Ruinas de Palmyra, near Olinda, State of Pernambuco. See page 22.

PLATE 15.
Cape Branco, coast of Parahyba do Norte. The cape bears S.50° W. See page 23.

PLATE 16.

The sandstone reef at Natal, Rio Grande do Norte, looking northward from the
lighthouse on the reef. See pages 35-39.

PLATE 17.

Looking south from the anchorage behind the reef at Natal, Rio Grande do Norte.
See pages 35-39.

bo

78 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY.

s PLATE 18.

The dunes south of Rio Grande do Norte, near the mouth of the river. See pages
35 and 121.

PLATE 19.

The dunes north of the mouth of the river at Rio Grande do Norte This is a
characteristic bit of the coast north of Natal. See page 122.

PLATE 20a.

The northern end of the stone reef at Natal, taken from the anchorage behind the
reef. Part of panorama with Plate No.20b. See pages 35-39.

PLATE 20b.

The stone reef at Rio Grande do Norte, from the anchorage behind the reef. The
fort (Fortaleza dos Reis Mages) is built upon the reef. This plate forms a
panorama with Plate 20a. See pages 55-39.

PLATE 21.

The southern part of the Cunhahw stone reef, looking north from the dunes. See
pages 40-45.

PLATE 22.

Looking south over the north end of the Cunhaht stone reef toward Bahia Formosa.
See pages 40-45.

PLATE 28.

The north end of the Cunhahit stone reef at low tide where it joins the land. See
pages 40-45.

PLATE 24.

Looking northward toward Ponta da Pipa and the north end of the Sibauima reef.
See pages 40-45.

PLATE 285.

Boulder-like masses of sand held together by worms; on the beach one mile north
of Bahia Formosa. See pages 44 and 45.

PLATE 26a.

The south end of the Traigio sandstone reef, at low tide. (No. 26b joins this on
the right to form panorama.) See pages 45-47.

i i i

BRANNER: THE STONE REEFS OF BRAZIL. 279

PLATE 26b.

Part of the Traicio sandstone reef. (No. 26c joins this on the right, and 26a
joins it on the left.) See pages 45-47.

PLATE 26c.

Part of the Traicdo reef panorama. (No. 26d joins this on the right, and 26b
joins it on the left.) See pages 45-47.

PLATE 26d.

Part of the Traicéo reef panorama. (No. 26e joins this on the right, and 26c
on the left.) See pages 45-47.

PLATE 26e.

Part of the Traicado reef panorama. (No. 26f joins this on the right, and 26d on
the left.) See pages 45-47.

PLATE 26f.

Part of the panorama of the Traicao reef. (No. 26g joins this on the right, and
26e on the left.) See pages 45-47.

PLATE 26g.

The northern end of the Traicio sandstone reef. (No. 26f joins this on the left.)
See pages 45-47.

PLATE 27a.

The village of Traicdo on the Bay of Traicio, behind a stone reef. (This forms a
panorama with No. 27b on the right.) See pages 45-47.

PLATE 27b.

The village of Traicao in a grove of coco palms. Fish traps in the foreground.
Join this to No. 27a for panorama. See pages 45-47.

PLATE 28.

The sand neck separating Traigio Bay from Lagoa de Sinimbii. This neck is
occasionally encroached upon by the sea. See page 133.

PLATE 29a.

Traicio Bay and the northern end of Traicao stone reef. (No. 29b joins this on
the right to form panorama.) See pages 133 and 134.

280 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

> PLATE 29b.

The sand neck between Traicdo Bay and Lagoa de Sinimbi. Part of the Traigao
Bay panorama. Plate 29a joins this on the left.

PLATE 30.
The neck of sand between Traicao Bay on the right and Lagoa de Sinimba on the
left, looking northward. See pages 1383 and 134.

PLATE $31.

The northern end of Mamangudpe stone reef seen from behind the reef at low tide.
See pages 47-45.

PLATE 32.

Looking south along the Mamangudpe sandstone reef at low tide. See pages
47-55.

PLATE 33.

Looking north along the Mamangudpe stone reef; the tide not all out. See pages
47-55.

PLATE 34.

Looking southward, and showing the branching and bending of the Mamangudpe
sandstone reef. See page 48.

PLATE 35.

A break in the Mamangudpe reef caused by undermining. The blocks in the gap
are covered with seaweeds. See pages 47-55.

PLATE 36.
Looking northward along the seaward side of the Mamanguape sandstone reef.
See pages 47-55.
PLATE 37.
Looking northward along the outer side of the Mamanguape reef at low tide. See
pages 47-55.
PLATE 38.
Along the landward side of the Mamangudpe reef, showing blocks broken by the

surf from the outer face and thrown across the reef. The curving of the reef
is also shown. See pages 47-55.

BRANNER: THE STONE REEFS OF BRAZIL. 281

PLATE 39.

The vertical outer face of the Mamanguape reef, looking southward at low tide.
See pages 47-55.

PLATE 40.

Blocks of compact sandstone thrown by the surf across the Mamangudpe reef.
The inner reef crosses the middle of the background. See page 40.

PLATE 41.

A characteristic bit of surface etching on the Mamangudpe reef. See page 52.

PLATE 42.

The eroded surface of the Mamanguape reef partly covered with barnacles. See
page 53.

PLATE 48.

Sea-urchin holes in the seaward face of the Mamanguape reef. See page 43.

PLATE 44.

Looking southward near the southern end of the Mamangudpe reef. The Mirimiri
cliffs are visible in the distance. See pages 47-55.

PLATE 45.

Mamanguape Point, and the southern end of the inner reef seen from the outer reef,
looking westward. See page 55.

PLATE 46.

The sand plains at Cabedello, Parahyba do.Norte. Photograph by Mr. Sumner.
See pages 232-235. :

PLATE 47.

The Pernambuco stone reef. Photograph taken in 1876 by the Commissio Geo-
logica. See pages 60-67. -

PLATE 48.

The Pernambuco reef taken from the old Dutch fort. See pages 60-67.

PLATE 49.

Surface of Pernambuco reef. Photograph taken in 1876. See pages 60-67.

282 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

. PLATE 50.

Pernambuco reef rock bored by sea-urchins. See pages 60-67.

PLATE 51.

The sandstone reef on the beach north of Gaibu, seen from above the old Dutch-
fort at Gaibti. See pages 69-71.

PLATE 52a.
The sandstone reef running south from Cabo Santo Agostinho. (No. 52b forms
a panorama with this.) See pages 71-78.
PLATE 52b.
Part of the panorama of the sandstone reef south of Cabo Santo Agostinho. This
view joins No. 52a on the right. See pages 71-78.
PLATE 58.

A part of the Cabo Santo Agostinho reef near its southern end at Camboa. The
sand flat between the reef and the shore is uncovered at low tide. See pages
71-78.

PLATE 54.

The stone reef south of Cabo Santo Agostinho seen from near its southern end and
from the rear at low tide. There is a long pool of water on top of the reef at
this place. See pages 71-78.

PLATE 55.

The sandstone reef near the lighthouse at Bahia. Photograph taken in 1876. In
1899 these vast rocks had all been quarried out. See pages 93-95.

PLATE 56.

The north end of the sandstone reef at Santa Cruz, State of Bahia. See page 95.

PLATE 57,
The stone reef at Porto Seguro, State of Bahia. Photograph taken from a steamer
inside of the reef at high tide. See pages 97-99.
PLATE 58.

Copy of the map of Pernambuco and the reef published by Caspar Barlaeus in
1647. See page 116.

s,

———

BRANNER: THE STONE REEFS OF BRAZIL. 283

PLATE 59.

View of the stone reef at Pernambuco, drawn by F. Post in 1645 and published
by Barlaeus in 1647. See page 202.

PLATE 60.

Map of the stone reef at Cabo Santo Agostinho, published by Caspar Barlaeus in
1647. (Rerum per octennium in Brasilia op. p. 140.) See page 71.

PLATE 61.

Map of the stone reef at Natal, Rio Grande do Norte, published by Barlaeus in
1647. Compare Fig. 15, page 37.

PLATE 62.

Fortaleza dos Reis Magos — the fort on the sandstone reef at Natal, Rio Grande do
Norte. Probably drawn by F. Post about 1645 and published by Barlaeus in
1647. Compare Plates 20a and 20b.

PLATE 68.

Tertiary(?) bluffs at Bahia Formosa, State of Rio Grande do Norte. The sloping
upper beds are old sand dunes. See page 122.

PLATE 64.

Tertiary (?) bluff at Pipa, with brown sand on top of it. Looking westward from
the anchorage. Bluff about two hundred feet high. See also Plate 63.

PLATE 65.

Characteristic topography of the Pernambuco coastal sand plain near Boa Viagem.
See pages 137 and 138.

PLATE 66.

Tertiary bluff at Santa Cruz, State of Bahia. See pages 141-142.

PLATE 67.

The gorge of the Rio Sao Francisco, at Piranhas. See page 148.

PLATE 68.

An elevated beach at Ponta de Areia, Bay of Bahia, two kilometres north of Sao
Thome. See page 150.

284 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY.

PLATE 69.

The terrace at Opdba, Boa Vista Fazenda, just north of Ilheos, State of Bahia.
See pages 154 and 155.

PLATE 70.

The terrace at Vellosa, about two kilometres north of Ilheos, State of Bahia. See
page 155.

PLATE 71.

The penedo, a peak of exfoliated granite at Victoria, State of Espirito Santo. See
page 158.

PLATE 72.
A line of pits on the granite peak at Victoria, Espirito Santo, showing recent ele-
vation of the coast. Photograph taken from a passing steamer. See page 158.
PLATE 73.
Sea-urchin burrows in blocks of trachyte on the beach three hundred metres north-
west of Pedras Pretas point, coast of Pernambuco. See page 159.
PLATE 74,

Young mangroves, showing how the roots spread through the water; Affogados,
near Pernambuco. See page 167.

PLATE 75.

General view of the edge of a mangrove swamp, showing the close-set plants. See
page 167.

PLATE 76.

Coral reefs, three kilometres south of Sio Miguel, Siate of Alagéas. There is
one coral reef on the horizon, one in the middle background, and one in the
foreground overlapped by beach sands. See page 242.

PLATE 77.

The Maceio coral reefs seen from the beach at Jaragua, State of Alagoas ; low tide.
See pages 270-274.

PLATE 78.

The Itaparica coral reef south of Bahia. Photograph made in 1875 by the Com-
missio Geologica da Brazil. See pages 246-249.

BRANNER: THE STONE REEFS OF BRAZIL. 285

JA by) AE)

Burrowed dead coral reef, Itaparica, State of Bahia.

PLATE 80.

Barnacles on the surface of a dead coral reef, Itaparica, Bahia.

PLATE 8la.

The Lixa coral reef, off the Caravellas coast, State of Bahia. The photographs
were taken shortly after the reef was fully uncovered, looking across the reef
at its widest part. (No. 81b joins this on the right to form a panorama.) See
pages 251-256.

PLATE 81b.
For title see No. 8La, which joins this on the left. See pages 251-256.

PLATE 82a.

View on the Lixa coral reef at low tide, looking N. 80° W. toward the land.

PLATE 82b.

Lixa coral reef near the northern end, looking N. 25° W. at low tide. See pages
251-256.
PLATE 82c.

Lixa coral reef at low tide, looking S.64° W. The pools are only a few inches
deep. (No. 82d joins this on the right for a panorama.) See pages 251-256.

PLATE 824d.
For title see No. 82c. This overlaps No. 82c somewhat on the right. See pages
251-256.
PLATE 88a.

Panorama of the coast north of Maceio, seen from the lighthouse on the hills
above the city. (Two others, 83b and 83c, join this on the right.) See
pages 130 and 164. i

PLATE 83b.
The coast north of Maceio. Panorama with Nos. 83a and 83c. See pages 130
and 164.
PLATE 8S8c.

The coast north of Maceio. Panorama with Nos. 83a and 83b. See pages 130 and
164.

t=
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wh &

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VIEW OF THE STONE REEF NEAR PERNAMBUCO.

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THE STONE REEF AT CABO SANTO AGOSTINHO

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MAP OF THE STONE REEF AT NATAL.

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THE GORGE OF RIO SAO FRANCISCO.

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DHE TERRACE AT VELEOSA,

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‘NOILWAR TA LNAOFY ONIMOHS ‘OLNVS OLINIdSH VINOLOIA LV SLId

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BRANNER REEFS.

SEA-URCHIN BURROWS IN BLOCKS OF TRACHYTE

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GENERAL VIEW OF THE EDGE OF A MANGROVE SWAMP.

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‘Sdasead TvadOd OL9OVWN FHL

Oe eat ‘SHday NaNNVAG

VIHVad dO HLNOS Heea TvaoOo VOldvVdVLI AHL

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‘GNH NAAHLYON AHL YVAN AXHA TVaAOO VXI1

828 Td ‘SHaaQ] YANNVAG

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‘OIMOVN HO LSVYOO HLYON

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‘OIHOVW AHO LSVOO HLYON

agg “1g “Sdddy YaNNvag

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GINDING SECT. MAY 16 1966

QL Harvard Universitye Museum
1 of Comparative Zoology
H3 Bulletin
Ve44
Biological’
| & Medical
Serials

| PLEASE DO NOT REMOVE

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