120 
Ohio Biological Survey 
courses of its tributaries reach an altitude of 500 feet, rising upstream 
to 600 feet in the vicinity of Hamilton and Loveland. This large area 
is occasionally flooded, and supports the characteristic flood plain vege¬ 
tation of the region. 
Thus it may be seen, that the topography of the region presents a 
complex of forms—some erosional and some constructional. Uplands, 
flat or rolling, broad or much dissected; ravines and valley slopes; broad 
flood plains; glacial terraces and filled valleys, are striking features of 
the topography. Fig. 7 is a view showing parts of each of the principal 
topographic areas. 
Soil water is a controlling factor in a consideration of the vegetation 
of these four areas. While the water table in general conforms to sur¬ 
face contour, it is nevertheless in a measure dependent upon the character 
of the soil. The approximate position of the water table in the four 
areas is shown in the accompanying diagram (£g. 2 ). 
The compact clays of the upland retain the ground-water, so that 
in wet seasons, the water table beneath the broad uplands may rise to 
within five feet of the surface, while in spring it so nearly coincides with 
the surface, that depressions but a few inches 'deep are filled with water 
for several months. Cultivated fields in such areas are always trenched 
at ten or twelve foot intervals, and it is no uncommon sight to see the 
trenches filled with water, and the fields dotted over with crayfish holes. 
The different rock formations differ in their ability to retain water. 
Both the Richmond and the Maysville, because of their relatively large 
percentage of limestone, are traversed by numerous solution channels, 
through which ground-water rapidly drains away. The Eden shale, 
which is very impervious, nevertheless has little effect upon the water 
table, for it is never the surface rock over any considerable area. 
Terrace gravels and the deeper valley fillings are much alike in their 
high water capacity (porosity 25 to 40%)^; but the loose gravels are un¬ 
able to hold the ground-water much above neighboring drainage lines. 
For this reason, the water table is relatively high in the pre-glacial valleys 
no longer occupied by large streams, and low in terraces, which usually 
stand from 40 to 70 feet above the flood plain or stream which they border. 
In the flood plain area, the height of the water table necessarily 
varies with stream height, rising with the spring floods, and sinking during 
the dry summers. Here flood water and not ground-water, is the impor- 
^ U. S. Geol. Surv., Water-supply paper 259, p. 32. 
