320 The American Geologist. November, i904. 
other South American geology. He has repeatedly visited 
and reviewed portions of the field of study, and finally re- 
ceived the assistance of Dr. Alexander Agassiz by which he 
has been enabled tO' make a somewhat exhaustive study and 
final publication of one of the most far-reaching investiga- 
tions. The problems involved are complex and difficult to be 
compassed except by long res'earch and comparative study. 
The subject of this investigation is one that is new to 
geological literature, and the methods of investigation had to 
be determined as the aspects of the problem were discovered. 
Hence it is entirely an original investigation. The geologists 
of North America may not at the outset take due notice of 
tliis work. But it will repay a careful reading. It brings to 
light some oceanic effects along coast lines which are either 
unknown or at least are obscure and unappreciated. It will 
add a new chapter to the dynamics of oceanic geograph}-. 
Except for minor interruptions due tO' local conditions 
and agencies these reefs are formed along the east coast of 
Brazil by forces that have acted from Maranhao to southern 
Bahia. Many of the important harbors and the towns located 
on them are due to the existence of the reefs. "Without these 
reefs there would be no Pernambuco, no Rio Grande do 
Norte, no Porto Seguro, no Santa Cruz, to say nothing of 
minor ports like Rio Formoso, Serinhaem, Tuape, Traicao, 
Mamanguape, and many others where the sugar boats load 
and take refuge along the whole coast from southern Bahia 
to Ceara and Maranhao." 
■ Nearly all former observers have confounded the stone 
reefs with coral reefs, but the latter are more extended, run- 
ning along the coast from the Abrolhos islands in south lati- 
tude 1 8°, nearly to the mouth of the Amazon river. Thes'e 
reefs, therefore, both affect that part of South America that 
forms the great nose or eastern projection of the coast line. 
Dr. Branner thus summarizes their geological and geographi- 
cal peculiarities : 
1. They are of sand consolidated to a hard — in places 
almost quartzitic — standstone. 
2. They stand about flush with the water at high tide, 
while at low tide they are left exposed like long, low. fiat- 
topped walls, with a width of from five meters' to one hun- 
