Quaternary Deposits, Etc. — Mills. 357 
surface. The itacolumite is comparatively hard and resists 
erosion far more than the softened slates, still the streams flow 
over it with rapid currents, and in places fall over precipices 
of it, and would erode deep into it in comparatively short 
geological time ; and the fact that the erosion has been so 
slight since the uplifting took place which gave to the streams 
their present fall and rapid currents, goes to confirm the con- 
clusion that the uplifting is of Quaternary or recent time. 
The loess of the region has the principal characteristics of 
loess generally; it is of fine material and of even fineness 
throughout, showing very little if any sorting of material or 
distinguishable stratification except near the bottom where it 
sometimes mingles with sand or passes into it by gradation. 
It is not traceable to the rocks immediately underlying it as is 
the cascalho when not transported by streams ; but neverthe- 
less its character is modified by that of the rocks prevailing 
in the vicinity. Where sandstone outcrops over a wide area 
the loess is sandy, and where shales outcrop over a wide area 
the loess is clayey, and where iron oxides abound the loess is 
of a red color ; and as iron oxides do abound in the shales 
generally, the loess is a kind of red clay over the large portion 
of the region where shales outcrop. Where gneiss is the pre- 
vailing rock the loess is sometimes red and sometimes of a 
drab color. 
The loess is more wide-spread than the cascalho. It gen- 
erally overlies the latter where it occurs except along the 
streams, and also rests upon the rock where the gravel is ab- 
sent. Before the erosion caused by the Quaternary or recent 
uplifting, it must have spread out far and wide over the sur- 
face of the region except where streams were flowing, and ex- 
cept isolated areas of bare rock at and near peaks and crests. 
Its vertical range is great ; it passes up mountain slopes and 
down into valleys, and in this respect it differs from loess over 
large areas in other parts of the world where it occurs on level 
or gently rolling plains or valleys rather than on mountain 
slopes. But as already shown when the softening of the rock 
took place and when the greater part of the cascalho was de- 
posited the region was a low-lying one, and for reasons to be 
hereafter given I conclude that it was still a low-lying region 
as a whole when the loess was being deposited, altliough tlie 
uplifting had begun. 
