756 THE JOURNAL OF GEOLOGY. 



Amazon valley he examined the table-topped hills x which 

 Agassiz had referred to glacial action, and the boulders he had 

 called "the only genuine erratic boulders " he had seen in the 

 Amazon valley. Already, in 1867, Professor James Orton, who 

 scouts the idea of the glaciation of the Amazonas, had discov- 

 ered at Pebas, in the supposed glacial sediments, "marine or 

 perhaps rather brackish water Tertiary fossils." 2 



In 1 87 1 Hartt found the supposed erratics of the Amazon val- 

 ley to be boulders of decomposition derived from trap dikes near 

 at hand, and stated that he " did not see, either at Erere or in any 

 part of the Amazonas, anything that would suggest glaciation." 3 

 He still clung, however, to the idea that the highland of Brazil 

 to the south had been glaciated. 4 



Unfortunately Hartt has left no further record of his later 

 views upon this subject, but that his views underwent a 

 radical change I know as positively as one can know the 

 opinions of another person. I went with him to Brazil in 

 1874, was with him in his work there until his death in 1877, an d 

 remained yet five years later — in all eight years in that country. 

 Under his direction I did more or less work in the mountains 

 about Rio de Janeiro for the purpose of sifting the evidence of 

 glaciation in that region, and I am glad to say, in justice to the 

 memory and scientific spirit of my former chief and friend, 

 that long before his death he had entirely abandoned the theory 

 of the glaciation of Brazil, whether general or local, and that the 

 subject had ceased to receive further attention, even as a working 

 hypothesis. So much for Hartt's opinions. 



'Bulletin of the Buffalo Soc. of Natural History, 1874, 201. 



2 On the Valley of the Amazon, by James Orton, Proc. Arn. Assoc. Adv. Sci., 1869, 

 XVIII., 195-9 ; O n the Evidence of a Glacial Epoch at the Equator, by James Orton, 

 The Annals and Magazine of Natural History, 187 1, VIII., 297-305. 



The Andes and the Amazon, by James Orton, N. Y., 1876, 282, 560. The fossils 

 collected by Orton are described in the Amer. Jour. Conchology, IV., 197, and VI., 192. 

 Others are described from similar places in the Quar. Jour. Geol. Soc, XXXV., 76-88, 

 and 763 et seq. 



3 Amer. Jour. Sci., 1871, 295. 



4 Ann. Rep. of the Amer. Geographical Soc. of N. Y., for the year 1870-1, 252. 



