GEOLOGT. 37 



by water — the sea. They lay in every inclination with the 

 horizon, and were deposited by the deluge, where they were 

 found. 



At Louisville, Kentucky, when digging the canal there, on 

 the surface of a flat rock, many feet below the surface of the 

 earth, above the rock, the works of man, were found. Fires 

 had been made on the rocks and men had dwelt there. Since 

 these fires had ceased to burn there, several feet of earth had 

 accumulated on the surface of the rocks, and trees, of the larg- 

 est size, had been growing on that earth, during several cen- 

 turies. 



SLATE AND LIMESTONE REGIONS. 



West of the geological line, before mentioned, the minerals 

 are very different from those of the hilly region, which we 

 have been considering. Several of the counties, lying along 

 this line, west of it, are underlaid, with clay slate, such as 

 we have noticed near lake Erie. Such a slate underlays the 

 western parts of Pickaway and Franklin counties. It pre- 

 dominates all over Madison county; mostly so in Fayette 

 county, and in Union county also; — as well as in the eastern 

 parts of Clark, and Clinton counties. 



Where that blue slate underlays the surface, and comes to, 

 or near it, the slate dissolves into a blue clay, and produces 

 swampy lands. We refer our reader to the Licking summit; 

 and, indeed, to nearly all our summits, north of our hilly re- 

 gion, or west of it, where he will find such clay, and such 

 swamps. Hence, the origin of most of our ponds, swamps 

 and wet lands, all over this state. They exist nearly all the 

 way across this state, from the Pennsylvania line, to that of 

 Indiana, on the summit level, between the Saint Lawrence 

 and Mississippi valleys. 



LIMESTONE. 



Ours is a subspecies — the compact limestone, and is a very 

 valuable mineral. It usually occurs, in extensive, solid, com- 



