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 Alagoas lakes, for he says 

 (p. 422) : "These lakes of Alagoas, 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.^ The wind-bedding could only be produced 

 above water. This shows that there has been a depression of the laud 

 since the sands were deposited. 



Elis^e Reclus hi 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.)." 



^ J. C.Branner. The supposed glaciation of Brazil. Journ.Geol., 1893, 1., p. 753-772. 



- J. C. Branner. Geology of Fernamlo do Noronha. Amer. Journ. Sci., 18S0, 

 XXXVII., p. 160-161. 



J. C. Branner. The ajolian sandstones of Fernando de Xoronha. Amer. Journ. 

 Sci., 1890, XXX., p. 247-257. 



8 Elise'e Reclus. Nouvelle ge'ographie universelle. Tome XIX. Amerique du 

 Sud, p. 146. Paris, 1894. 



* Henri A. Coudreau. Voyage a travcrs les Guyanes et TAmazonie, p. 

 10-11. Paris, 1887. 



