100 A JOURNEY IN BRAZIL. 
the g;triae 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 tho 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 Geriies, the thriving coffee plantations are upon erratic 
