PHYSICAL HISTORY OF THE AMAZONS. 399 



existed at all, it must have been cosmic ; and it is quite 

 as rational to look for its traces in the Western as in the 

 Eastern hemisphere, to the south of the equator as to the 

 north of it. Impressed by this wider view of the subject, 

 confirmed by a number of unpublished investigations 

 which I have made during the last three or four years 

 in the United States, I came to South America, expect- 

 ing to find in the tropical regions new evidences of a 

 bygone glacial period, though, of course, under different 

 aspects. Such a result seemed to me the logical se- 

 quence of what I had already observed in Europe and in 

 North America. 



On my arrival in Rio de Janeiro, the port at which 

 I first landed in Brazil, my attention was immediately 

 attracted by a very peculiar formation consisting of an 

 ochraceous, highly ferruginous, sandy clay. During a stay of 

 three months in Rio, whence I made many excursions into 

 the neighboring country, I had opportunities of studying 

 this deposit, both in the province of Rio de Janeiro and in 

 the adjoining province of Minas Geraes. I found that it 

 rested everywhere upon the undulating surfaces of the 

 solid rocks in place, was almost entirely destitute of strat- 

 ification, and contained a variety of pebbles and boul- 

 ders. The pebbles were chiefly quartz, sometimes scat- 

 tered indiscriminately throughout the deposit, sometimes 

 lying in a seam between it and the rock below : while 

 the boulders were either sunk in its mass, or resting loose- 

 ly on the surface. . At Tijuca, a few miles out of the city 

 of Rio, among the picturesque hills lying to the south 

 west of it, these phenomena may be seen in great per- 

 fection. Near Bennett's Hotel there are a great num- 

 ber of erratic boulders, having no connection whatever 



