384 Frank Carney 



shale and sandstone; the more resistant beds produce shghtly 

 greater surface irregularity . For some distance after the traveler 

 has passed the center of the state, he finds himself in more hilly- 

 country, where coarse sandstone and conglomerate horizons are 

 on the surface. Following this he enters the coal region, where 

 the sandstone and conglomerate beds are heavier and have 

 better withstood the effects of erosion, giving rise to the most 

 irregular topography in the state. Towards the Ohio river, the 

 streams become more numerous, and the relief more mature. 



Had this traveler turned southward from Toledo, soon he would 

 have found himself near the axis of the Cincinnati arch where the 

 formations dip in either direction, on his way to Cincinnati; for 

 some distance the relief is mild, and large streams are wanting, 

 but approaching the Ohio river, the limestone has been cut by 

 streams, and greater surface irregularity exists. 



Other influences in relief. Thus the rocks have a marked 

 influence on the elements of a landscape. There are, however, 

 some minor factors that tend to vary the relief which rocks would 

 otherwise always produce. Among these agents are glaciation, 

 and variation in stream history. The deposition of glacial drift 

 generally tends to make the surface features more regular; but 

 in some localities ice erosion has very appreciably increased 

 the relief. Crustal movements, orgogenic and epeirogenic, have 

 induced stream capture and divergence, which frequently account 

 for relief features that do not entirely reflect rock structure 

 and attitude. In another place I discuss these factors more fully 

 (pp. 199-202; 388-392). 



Physiographic regions of Ohio. Ohio cannot be parceled into 

 distinct physiographic regions. Its surface has pronounced 

 relief features, but these so blend into each other that it would 

 be rather arbitrary to draw lines of division. 



Along the Atlantic seaboard the coastal plain is distinctly 

 set off from the Piedmont belt by the Fall Line. This is a clear 

 cut physiographic boundary. Except for a short distance in the 

 vicinity of Cleveland, and east of that city, we have nothing 

 that even simulates this kind of a boundary. The following is 

 a suggested division for the physiographic regions of this state: 

 (1) the lake plain; (2) the plateau area. These divisions are 

 structural in origin. The first reflects to some extent the minor 

 factors in producing relief features, alluded to above. The second 

 division is dependent quite entirely on underground structure. 



