636 GEOLOGY OF OHIO. 
would necessarily follow, with the establishment of the terraces that 
make so conspicuous a feature in the valleys to-day. 
III. SOILS. 
The subject of the soils of the county follows next in order, and has, 
indeed, already been touched upon in the reference to the deposits that 
fill the Scioto valley. 
The Scioto valley is far more productive than any other equal area 
within the county. The variety of soils found within it has been indi- 
cated in the description of the different elevations which the valley de- — 
posits now hold. The two lower members of the series give excellent 
examples of alluvial soil. They constitute in Pike county, and below, 
one of the great corn fields of Ohio. They are planted every summer, 
and it is by no means uncommon to find eight or ten square miles of In- 
dian corn in one unbroken tract. The ordinary yield ranges between 
fifty and seventy-five bushels to the acre. 
The soil of the terraces is not thus renewed by natural agencies, and 
though still very productive, shows in a marked degree the incipient 
exhaustion that all of the land of this part of the State, except the allu- 
vial bottoms, exhibits under the system of tillage now in use. These 
areas have been growing less tractable of late years by the exhaustion of 
their organic matter. The plowing in of clover restores this element, 
and works admirably in ameliorating the lands that have grown stub- 
born. 
The remaining valleys of the county have not shared in the geological 
fortunes of the Scioto valley, and, consequently, lack its fertility. None 
of them contains limestone gravel to any extent. 
The intervals of the Sunfish are quite narrow, and the soil is de- 
cidedly inferior to that of the river valley. 
The clays of the Beaver, California, and Cynthiana valleys form for 
the most part cold soils, better adapted to grass than to cereals. 
The upland soils of the county are, without exception, native soils, 
formed where we find them by agencies such as we now see at work. 
Being made from different materials, as the different belts of the geologi- 
cal scale successively form the surface, they exhibit great differences in 
composition and character. Three general divisions will be recognized by 
every one acquainted with the county as dividing among them the up- 
land areas. They are the slate soils, the Waverly soils, and the conglom- 
erate soils. 
On the western border of the county, especially in Perry and Mifflin 
townships, we find the Huron shales largely displayed. The soil formed 
