128 GEOLOGY OF OHIO. 



mountain chain at points remote from the center of action. We find, 

 however, in the coal basin proofs of disturbances which took place long 

 anterior to the elevation of the Alleghany Mountains, by which the 

 parallelism of our coal seams was in many places destroyed. We also 

 have evidence that before the deposition of the lower coals the surface 

 in which they accumulated was quite irregular, and by these irregulari- 

 ties their continuity was locally broken, and their extent north and 

 east, definitely limited. We know that the Alleghany Mountains proper 

 had no existence till after the close of the Carboniferous age ; but the 

 Blue Ridge is much older, and our Alleghany coal field, during the depo- 

 sition of the Carboniferous rocks, was a broad, low plain — sometimes 

 above and sometimes below the water level — which stretched across 

 from the Cincinnati arch to the base of the Blue Ridge. This plain, or 

 bay, or lake — for it was all three at different times — had at the dawn of 

 the Coal Measure epoch a somewhat uneven bottom and irregular mar- 

 gin. Gravel hills which now form masses of conglomerate bounded it on 

 the north and were scattered irregularly over its surface, and here and 

 there along its western margin were ridges and knolls of Waverly 

 rocks, partly formed by erosion during the deposition of the Conglom- 

 erate, and partly due to f®lds which belong to the period of the Cincin- 

 nati arch. Over this surface the Coal Measures were deposited layer 

 after layer, like a fall of snow, filling all its valleys and burying its 

 hills, and producing finally an even and monotonous surface. The pro- 

 gress of this series of events was, however, not uniform, for, as we have 

 seen, the Coal Measure plain was at times elevated and deeply scored by 

 surface erosion ; but the irregularities produced at such times were all 

 obliterated by subsequent submergence and depositions. 



The uneven character of the bottom of the coal basin is well shown 

 by the interruptions of the lowest coal seam, which was apparently de- 

 posited in a marsh of which the margin was fringed with points and 

 headlands, and the continuity broken by ridges and knolls which rose 

 above its surface. Hence we find this seam occupying a series of chan- 

 nels and basins separated by barren intervals of greater or less extent. 

 These are fully described in the reports on Trumbull, Portage, Stark and 

 other counties, through which the outcrop of coal No. 1 passes. 



The buried hills of Waverly and Conglomerate rock which interrupt 

 the coal seams in the southern portions of the State are frequently re- 

 ferred to in the reports of Prof. Andrews. They also occur along the 

 western margin of the coal field north of the National Road, in Licking, 

 Knox, Richland, and Holmes counties. The most striking of these is 

 that seen along the line letween Richland and Holmes, where the Lou- 



