622 GEOLOGY OF OHIO. 



are isolated Drift-hills scattered over the water-plain, which is bordered 

 hy ridges of modified Drift. 



In the south part of the county the valleys are covered with a mixture 

 of alluvium and Drift, and the hills with Drift and the dehris of the 

 local rocks. The soil is clay, tempered with sand and gravel, and con- 

 taining a great abundance of rock fragments, while granite bowlders are 

 very abundant, some of them of several tons weight. The rock frag- 

 ments preserve the steep cultivated slopes from washing, and cause the 

 rains to penetrate the soil, and accomplish, to a great extent, the work of 

 underdrainage. These hills continue to bear good crops of wheat, as 

 well as of corn, oats, and other crops. The timber is beech, maple, oak, 

 chestnut, hickory, etc., and on the borders of streams, elms and black 

 walnut are occasionally found. In Hanover township the slopes of the 

 hills are ordinarily covered solely with the debris of the local rocks, and 

 the soil is less productive. The alluvium of the valleys renders them 

 fertile, and the greater part of the county has a rich, productive soil, 

 adapted to a mixed and varied husbandry. 



In the village of Ashland is a remarkable witness to the immense 

 transporting power of the agencies which brought in the Drift. This is 

 the remains of an enormous bowlder of granite, from which rock has 

 been occasionally quarried for foundation purposes for the last thirty or 

 forty years, and of which there is now enough remaining to load several 

 railroad cars. Its original dimensions exceeded 25 X 15 X 12 feet, and 

 it must have weighed over three hundred and fifty tons. Broken up, it 

 would have sufficed to load a railroad train of thirty-five cars. It is 

 greatly to be regretted that it was not preserved unbroken, as a very in- 

 teresting memorial of the past. 



GEOLOGICAL STEUCTUEE. 



The geological structure of the county is very simple, and easily un- 

 derstood. With the exception of a narrow ridge of the coal rocks, on 

 the south line of Hanover township, it is a continuation to the east of 

 the upper series of rocks exposed in Richland county, and is made up 

 entirely of the Cuyahoga shales, capped here and there in Hanover 

 township with a thin bed of the Sub-carboniferous Conglomerate. A 

 geological map of the county would have a small spot of brown shading 

 at the south-east corner of Hanover to represent the Coal Measures, two 

 or three small patches of red in the immediate neighborhood to designate 

 the Conglomerate ; and all the rest colored yellow to indicate the Waverly. 



The following is a section of the rocks disclosed in the south part of 

 Hanover township, where the highest geological formation is formed, and 



