100 A JOURNEY IN BRAZIL. 



the striae and furrows and polish which mark its track 

 in the temperate zone. These one can hardly hope to 

 find where the rock is of so perishable a character and 

 its disintegration so rapid. But this much is certain, 

 a sheet of drift covers the country, composed of a homo- 

 geneous paste without trace of stratification, containing 

 loose materials of all sorts and sizes, imbedded in it 

 without reference to weight, large boulders, smaller stones, 

 pebbles, and the like. This drift is very unevenly dis- 

 tributed ; sometimes rising into high hills, owing to the 

 surrounding denudations ; sometimes covering the surface 

 merely as a thin layer ; sometimes, and especially on steep 

 slopes, washed completely away, leaving the bare face of 

 the rock; sometimes deeply gullied, so as to produce a suc- 

 cession of depressions and elevations alternating with each 

 other. To this latter cause is due, in great degree, the bil- 

 lowy, undulating character of the valleys. Another cause 

 of difficulty in tracing the erratic phenomena consists in 

 the number of detached fragments which have fallen from 

 the neighboring heights. It is not always easy to distin- 

 guish these from the erratic boulders. But a number of lo- 

 calities exist, nevertheless, where the drift rests immediate- 

 ly above stratified rock, with the boulders protruding from 

 it, the line of contact being perfectly distinct. It is a curi- 

 ous fact, that one may follow the drift everywhere in this 

 region by the prosperous coffee plantations. Here as else- 

 where ice has been the great fertilizer, a gigantic plough 

 grinding the rocks to powder and making a homogeneous 

 soil in which the greatest variety of chemical elements are 

 brought together from distant localities. So far as we have 

 followed these phenomena in the provinces of Rio and Mi- 

 lias Geraes, the thriving coffee plantations are upon erratic 



