nn alle 
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 Ceará and Maranhäo. 
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. 
ІТ. 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 Ceará 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. 
Х. 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 Commissão 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- 
