18 THE PREGLACIAL DRAINAGE OF OHIO. 



feet. The old slopes were well graded and the angles of slopes 

 very low. It would have been considered very fair agricultural 

 lands. A photograph taken from our standpoint gives a good 

 idea of the features of this old form. The surface is seen now 

 dotted with farm houses and the cultivated lands of the region 

 are principally located on this old surface. 



On closer inspection it is observed that this rolling surface 

 is very deeply scarred by an extensive net work of narrow, deep 

 valleys which are present almost every where over the region; 

 the principal exception being along the present divide separat- 

 ing the waters of Wolf Creek from those of the Little Hocking. 

 The reasons for this notable exception will appear later. In 

 many places these deep valleys are scarcely more than narrow 

 gorges. They vary in depth below the old surface from ioo to 

 250 feet, depending upon their proximity to the larger streams. 

 Their slopes are so steep that they are rarely cultivated but are 

 usually covered with timber. They are such a barrier to the 

 construction of roads that over large areas there are two almost 

 distinct systems of highways, one the valley roads and the other 

 the ridge roads. These often parallel each other for many miles 

 without connection. The valley roads pass over the ridges at the 

 head water gaps where they are usually crossed by the ridge 

 roads. There is everywhere a well marked change in the angle 

 of the slopes between the old surface and the deeper valleys, 

 indicating very clearly the line between the old erosion cycle 

 and the more recent. So that the fact that the region has 

 experienced a very wide spread rejuvenescence is very apparent. 



The exceptions to these general features are rather local 

 and require a more detailed treatment. They are the flat low 

 lands associated with the present divides and the broad valleys of 

 the larger streams. 



CHARACTERS OF THE OHIO VALLEY. 



The Ohio River valley where it enters the region in the vicin- 

 ity of New Martinsville, is a very narrow gorge. 



The bordering hills are very steep, often exposing vertical 

 cliffs which rise to> the level of the adjacent table land. The river 



