44. GEOLOGY OF OHIO. 
the weathering of the blue clay, were exposed by a slowly advancing 
submergence to the action of waves or currents, it is easy to see that 1ts 
clay, sand and gravel would be assorted and separated. The coarser 
materials would be moved the least distance and the finer clays the 
greatest distance from their original beds. As the submergence was 
gradually extended, then we ought to find beds of gravel overlying the 
blue clay, themselves overlain by sand, and finally covered with the 
finest grained clays. Such is precisely the general order of the arrange- 
ment in all of these districts. We ought furthermore to expect that on 
the highest grounds of the county beds of gravel and sand would abound. 
This also is exactly the case. Ohlinger’s Hill, as high a point as is con- 
tained in the county, is the resort of the whole country for miles around, - 
for plastering sand, extensive deposits of which occupy the highest parts 
of the dividing ridge. 
The same line of facts is met with on the high ground west of London, 
a ridge scarcely inferior in elevation to the one already referred to. It — 
is, in fact, a part of the same water-shed—separating the drainage of the 
Scioto from that of the Little Miami. Almost the whole of this region 
is occupied with heavy beds of well-washed gravel. The whole supply 
for London and its vicinity isderived from this locality. It must, however, 
be noted that these high grounds also contain remnants of the old glacial 
clays, which furnish, as at Ohlinger’s Hill, a soil of entirely different 
properties from any otue. svils in the county. The difference lies in the 
fact that the high location of the masses has prevented the accumula- 
tion of vegetable matter in them. They produce fruit well and are good 
wheat lands when properly treated, but they are decidedly inferior as 
grass-lands to the rest of the county. In fact, but a thin sod establishes 
itself upon them unless special care is taken to secure this result. 
The submergence of this district and the consequences resulting from 
such a fact have been spoken of. It is easy to see that the emergence which 
converted it into dry land again, must have been attended with equally 
marked results. As drainage systems began to be established or re-estab- 
lished, the accumulations of clay, sand and gravel of the re-arranged drift 
would often be withdrawn from the surface over which they had been 
distributed, and the broad valleys through which currents were moving, 
would be sure to receive them. The bowlder clay would thus be exposed 
on portions of these areas. | 
The northern and central districts of the county contain almost all of 
the exposures of this sort, while the southern tiers of townships which 
lie a hundred feet or thereabouts lower than the above named districts, 
hold by far the most gravel. 
