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290 GEOLOGY OF OHIO. 
Wach of these narrow terraces is represented in Huron county by broad — 
expanses of level land, showing that they are old water plains; diversi- 
fied by sand dunes and remains of old lake beaches, and by the various 
channels excavated by the present streams. In the eastern and south- 
ern parts of the county the surface rises to a level, geologically and topo-. 
graphically, above the summit at Berlin Heights, and is marked ee irreg- 
gular undulating hills of the clay Drift. 
The topography is also modified by the valleys of the Vermillion and 
Huron rivers and their tributaries; the valleys showing old flood plains, 
in places from one-half to three-fourths of a mile wide, with bluffs from — 
fifty to sixty feet in height. Vermillion River has its source in Savan- 
hah Lake, Ashland county, where it connects with streams which are 
tributary to the Ohio; the valleys uniting at the divide in a continuous 
channel, now deeply filled with- Drift, indicating that the drainage of 
both valleys was formerly southward. The connection of the head-waters 
of Huron River with the streams running south is not so distinctly 
marked, yet it can easily be traced between them and two valleys, one to 
- the east and one to the west of Mansfield, in Richland county, where the 
drainage is also to the south. This is indeed a general characteristic of 
the streams in this part of the State, which have their origin near the 
divide, between the waters of the Lake and the Ohio River. They are i 
not separated by a water-shed, and fed by springs flowing from opposite 
sides of it, but take their common origin in valleys having a northerly 
and southerly direction, and usually commence in marshes or small’ | 
lakes, now occupying the summit of the pass. Here they receive the 
surface drainage from the higher lands on each side, which accumulates 
in the pond or marsh, and gives rise to streams flowing in opposite direc- 
tions. The valleys of these streams are filled with alluvium, resting 
upon Drift deposits; and they have rocky beds only in places where ob- 
structions have diverted the stream into new channels. 
SURFACE DEPOSITS. 
The surface ‘deposits of Huron county afford a good illustration of the 
influence of recent geological changes in preparing a soil fitted for the 
work of the agriculturist. The underlying rocks are sandstone, arvilla- 
ceous and bituminous shales, with a strip of lime rock in the north- 
western border of the county. The disintegration of these rocks in place 
would have formed a narrow belt of calcareous soil on the western mar- 
gin, next a broad, irrregular surface of tenacious clay, and over the rest 
of the county a soil of comparatively barren sand. These rocks have 
been broken up and pulverized by Nature’s vast ice-plow; the finely 
