36 Soils of Nebraska — Hicks . 
pods are, for the most part, preserved only as internal casts of 
the shell. 
The fact that a dolomitic bed near Andalusia passes , into a 
bed of sandstone farther west in the region of Pine creek, Iowa, 
would be in perfect accord with what I have already pointed 
out in the American Geologist for January, 1888, vol. i, page 
30—namely, that the great dolomitic masses of strata represent¬ 
ing the Niagara, Galena and Lower Magnesian limestones of 
Iowa, were formed off shores, and that farther seaward, or at 
least further to the south and west, where they are generally 
concealed by newer strata, the place of the dolomites was taken 
by sandstones and shales.* 
301LS OF NEBRASKA AS RELATED TO GEOLOGICAL 
FORMATIONS. 
By L. E. Hicks. 
The soiPupon which the farmer and fruit grower depends for 
the success of his labors is a thin stratum spread over the sur¬ 
face of the earth, varying from a few inches to two or three 
feet in thickness, and composed of two elements, humus and 
mineral matter. The first element is organic, derived chiefly 
from plants, but partly from animals, and has undergone partial 
decay. It is the essential element of fertility. But notwith¬ 
standing its prime importance it is, in point of origin, secondary 
and dependent upon the mineral matter. This possessed some 
degree of fertility in itself, and so produced a crop of plants 
whose decay enriched the place of their growth, and began that 
course of production and accumulation of humus which has re¬ 
sulted in the elaboration of the deep black soils which rejoice 
the heart of the Nebraska farmer. The mineral element of our 
soils varies greatly in composition, and these variations bring 
to view at once the relation of soils to the underlying rocks. 
It might be supposed that so thin and superficial a stratum as 
the soil, a stratum, too, which derives its most characteristic 
.element from organisms growing freely in the air, would be in¬ 
dependent of the rocks beneath. The bed rocks are often 
*Notes on the Formations passed through in boring the Deep Well at 
Washington, Iowa, by Professor S. Calvin, American Geologist, vol. i, p. 
:28 et. $eq. Published January 1888. 
