SUPPOSED GLACIATION OF BRAZIL. j6j 



These materials are made up of boulders, cobbles, and gravels, 

 sometimes assorted and sometimes having sand and clay mixed 

 with them, and are spread far and wide, though irregularly, over 

 all the Tertiary and Cretaceous area bordering the ocean, and 

 extend for a long distance into the interior, and far beyond the 

 borders of the Tertiary deposits. They were regarded by the 

 writers in question as analogous to the water-worn materials so 

 common in the northern drift. Had these materials been of 

 glacial origin it is not unreasonable to expect that striated 

 pebbles would have been found among them occasionally, but, 

 as a matter of fact, no such marks have ever been found, though 

 I have made the most diligent search for them. That the striae 

 have been obliterated by weathering agencies is out of the 

 question, because the preservation of the water-worn and pitted 

 faces of the pebbles shows plainly enough that striated faces 

 would have been preserved equally well had they ever existed. 

 The origin of these water-worn materials has already been 

 explained elsewhere, and from that article the following quota- 

 tion is made : r 



" This formation is spread over the hills and valleys of the Sergipe- 

 Alagoas basin and over the adjacent country in the form of a thin coating of 

 cobblestones, pebbles and sand, sometimes loose and sometimes cemented 

 into a pudding-stone as much as ten feet in thickness, and, when exposed, 

 stained black by manganese. It caps the summit of the tertiary plateaux or 

 their outliers, and it is frequently strewn along down the sides of hills and 

 accumulated in the valleys. It is not confined to the geographic limits of the 

 Cretaceous or Tertiary, but is found further inland and far beyond the present 

 limits of these formations. It is everywhere more or less irregular in thick- 

 ness, and nowhere can it be said to be universal or continuous. The writer 

 has seen this material throughout Sergipe and Alagoas, in Parahyba, and as 

 far inland as the head waters of the Rio Ipanema in the interior of the pro- 

 vince of Pernambuco, where there is no remnant of stratified Tertiary beds. 

 Between the lower Rio Sao Francisco and the frontier of the province of 

 Alagoas, and indeed in many parts of the province of Pernambuco, this water- 

 worn material is found mingled in bogs with the remains of extinct, gigantic 

 mammals. 



One of the marked characteristics of this post-tertiary formation is that it 

 is much coarser inland, and grows finer as the coast is approached. The 



'Trans. Amer. Phil. Soc, 1889, XVI., 421. 



