4 Introductory Views. 



and this not from any dip in an opposite direction, for the indlnation 

 'of the strata is with the course of the stream, that is, towards the 

 Ohio river, or the center of the valley. 



This fact is finely illustrated in a deposit of coal, lying on the 

 heads of Duck creek and in the ridge, which divides these waters 

 from those of Will's creek, in Ohio. The hills are about three 

 hundred feet in height, and the place here spoken of is about thirty 

 eight miles north of Marietta. A bed of coal, five feet in thickness, 

 appears on the face of the hills at an elevation of two hundred feet 

 above the bed of the creek, and is also found for many miles around 

 in the adjacent hills on the opposite side of the valley, and at the 

 same elevation. The roof of the coal is composed of bituminous 

 shale, upon which rests a coarse sandstone of nearly eighty feet in 

 thickness. As we descend the creek, the coal approaches the sur- 

 face and the sandstone becomes more thin, until at the distance of 

 twenty five miles, the coal wholly disappears, with the stratum of 

 sandstone rock, and the strata below come to the surface in nearly 

 the same order in which they appear at the distance of twenty five 

 miles above. The inference is, that this coal deposit had been laid 

 bare by the wasting away of the superincumbent strata, ^nd had 

 finally itself been decomposed by the action of the atmosphere and 

 frosts, and washed away by the rain. The operation is still going 

 on ; and rock strata and coal, are daily laid bare and are found wast- 

 mg away m the beds of streams, and torrents in the elevated parts 

 ot the valley The same process which cut away the sandstone rocks 

 m forming the bed of the Ohio, is still in force in the small streams 

 and nvulets which run into it from the hills. If it is a considerable 

 stream the strata of rock are cut away, at the mouth, as low as the 

 bed of the nver, and as you approach the hills and ascend towards 

 Its head, the bottom of the stream is composed of sandstone rock, 

 with occasional cascades, over which the water, as it falls, acquires 

 force m proportion to its elevation, and finally wears away the solid 

 rock till a 1 obstructions are removed. Examples may be seen in 

 all the hill and mountain torrents. The process now pursued by 

 • the smaller streams, is doubtless the same with that of the larger in 

 , by-gone ages. ^ 



Jl'Tr P^^^^^^^^^^t before the growth of trees, shrubs, and 

 grasses had commpnopH r.r K^^ ^....i ^ . . \. 



rarment 



mom Affin;^^* J 1 , -^ ** ^cixuieui, ueoacies were 



more efficen,, and the abrasion, of the surface by rains and torrents, 



