Quaternary Deposits, Etc. — Mills. 353 
They consist, as in the Rio Grande do Sul, of two groups, 
namely, of cascalho and loess. The cascalho of Minas Geraes 
has been the source of the larger part of the great gold prod¬ 
uct of Brazil. 
The cascalho began to be deposited before the loess, but a 
part of it is contemporary with the loess, and erosion since the 
time of the deposition of loess has added gravel as in Rio 
Grande do Sul, and to a larger extent than there. Recent 
erosion has also shifted and carried forward a part of the 
gravels that had been deposited before the loess. In fact the 
cascalho and loess have been removed from considerable areas 
by recent erosion which has cut down through these superficial 
deposits into and sometimes through the underlying layer of 
softened rock; still much the larger part of the surface is cov¬ 
ered with these loose materials. They extend through a wide 
range of elevation. Going from the Parahyba up the south¬ 
easterly slope of the Mantiqueira range one sees exposures of 
gravels with overlying loess in places from the foot of the slope 
to the saddle through which the railroad passes over the crest, 
and such exposures continued west of the crest down to the 
streams and over the divides onward to Diamantina, or as far 
north as I had opportunity to observe. I ascended but one of 
the highest peaks—Itacolumi—and I recall that on the upper 
portions of the mountain from elevation of about 4,000 feet to 
the summit the rocks were nearly or quite bare of Quaternary 
deposits; but I did not make a definite note of the fact at the 
time. 
On the southeasterly slope of the Mantiqueira, and between 
the crest of that range and Itacolumi mountain there are fre¬ 
quent exposures of cascalho containing or associated with 
clays in places, and these clays are commonly more or less 
Carbonaceous. In places the cascalho consists entirely of clay. 
Between where the road crosses the spur of Itacolumi south 
of Oaro Preto, and Diamantina the road passes for a large part 
of the way over a series of sandstones (itacolumites, etc.) and 
shales which contain great masses of specular iron ore as 
above mentioned, and also large proportions of oxides of iron 
disseminated through the sandstones (itabyrites) and rocks 
generally. And here oxides of iron chemically precipitated 
form a considerable part of the lower group of Quaternary 
loose materials,—the cascalho, between the villages of Infic- 
