Soils of Nebraska — Ricks. 
39 
quality. As the basis of soils these coal measure shales are good 
or bad according to the other elements mixed with them. 
Shales alone will weather down to a soil which is heavy and 
difficult to till. But if mixed sufficiently with sand and lime 
a rich loam will be the result. The shales of the Coal Measures 
are often calcareous enough to furnish the lime necessary for a 
good soil, and if not, the presence of limestones in the same for¬ 
mation yields a happy combination. The sandy element, which 
is needed to combine with the disintegrated shales in order to 
make a light, tillable soil, is furnished by the glacial drift and 
loess; two formations which lie upon the bed rocks in Eastern 
Nebraska. These are the newest of the Nebraska deposits (ex¬ 
cept the alluvium which is still forming along the streams) as 
the Coal Measures are the oldest, and they will be described in 
the proper place. 
The limestones of the Coal Measures are the most important 
of the series in point of their economic value for lime and build¬ 
ing stone, as well as their influence on the soil. The decay of 
limestones always tends to enrich the soil—a fact so obvious as 
to challenge the attention of the most careless observer. Lime¬ 
stones weather and decay much more rapidly than is generally 
supposed. The carbonic acid of the air and water attacks them 
with great vigor. Frosts crack their surfaces and the roots of 
plants enter and enlarge the fissures by their growth. Little 
by little the rock is broken down or dissolved, yielding its 
nutritive elements to the soil. 
I have stated that the oldest rocks in Nebraska are in the 
south-eastern corner. Going westward from the Missouri river 
one constantly encounters newer rocks lapping over on the 
older ones. Passing from Pawnee to Gage county we pass from 
the Coal Measures to the Permian, the last series of the Carbonic 
system. The rocks of this series are very similar to those of 
the Coal Measures, the distinction between the two being based 
upon a difference in the fossils and the absence of coal. Hence 
in the area underlaid by Permian rocks the same soils may be 
found (so far as they depend upon the subjacent rocks) as in 
the counties where the rocks belong to the Coal Measures. The 
Permian occupies about two-thirds of Gage county and small 
portions of Saline and Lancaster counties. 
After the Permian epoch there was a long interval during 
