414 THE CKETACEOUS AND TERTIARY GEOLOGY 



correctness of this reference. What portion or portions of the European or North 

 American tertiary they re])rescnt it is quite impossible to say. In general appearance 

 the deposits bear a strong resemblance to some of the later tertiary formations of the 

 Southern United States, though the materials of the two are derived from very differ- 

 ent geologic sources. 



Absence of Fossih. — It is a peculiar feature of the Biazilian tertiary that with 

 the exception of a few plants found in the Amazon region, fossils have never been 

 discovered in it. That fossils should not be preserved in beds of such thickness and 

 vi^de distribution, made uj) of strata of sands and clays variously commingled, is cer- 

 tainly to be wondered at. The statement of the fact has often been questioned, and 

 explained by the assumption that careful search has not been made for them. That 

 they may yet be found is of course highly probable, but the writer has searched miles 

 of exposures in vain for any recognizable ti'ace of organic remains. 



Several hypotheses suggest themselves in explanation of the non fossiliferous 

 character of these rocks. After examining the geology of the Amazon region, 

 Agassiz concluded that an enormous glacier once moved down that valley, and built 

 up across its eastern end a gigantic moraine ; that as the ice melted the formations 

 which ai-e now believed to be tertiary were deposited from the cold, muddy waters 

 flowing from the glacier into a great lake. This, to his mind, explained also the 

 absence from these beds of organic remains other than leaves. But even if Prof. 

 Agassiz's theory of the origin of these Amazonian beds wei"e accepted* it would not 

 explain the absence of fossils from the same rocks along the south-eastern coast of 

 Brazil. 



Two hypotheses are offered : The first is, that these rocks were deposited so 

 rapidly, and from water so overloaded with mechanically suspended matter, that ani- 

 mal life in them was impossible. It may be said in regard to this theory that while 

 most of the teitiary beds are of a nature which would support it, there are many 

 beds of clays and very fine sands which would hardly be deposited rapidly or from 

 strong currents (see section on p. 410). 



The second hypothesis is that these beds once held organic remains, but that 

 they have been dissolved out by infiltrating waters. 



Present Extent of the Tertiary. — The present distribution of the tertiary beds in 

 the Sergipe-Alagoas basin cannot be given except in general terms, but from the 

 explanation of its relations to the cretaceous roclvs of the region (y. p. 37G) one will 



* Agassiz's theory has never been accepted by the geologists who are acquainted with the geology of the Amazons, 

 and he is said to have abandoned the theory of the glaciation of Brazil before his death. See Glaciers, by Slialer and 

 Davis, p. 47. 



