288 GLACIAL FORMATIONS OF ERIE AND OHIO BASINS. 



HOCKING VALLEY. 



The Hocking Valley appears to have beeu a line of vigorous dischai'ge 

 for glacial waters during the Illinoian ice invasion, there being a large 

 amount of gravel and cobble in its middle and lower courses outside the 

 limits of glaciation, which seems to have been derived from the Illinoian 

 drift. Much of the gravel has been carried beyond the supposed old 

 divide below Sugargrove, there being extensive remnants in the vicinity of 

 Logan and Haydenville; and also north of Athens. The old gravel has 

 Ijeen largely removed in the pai't of the valley above the divide down to a 

 level at least as low as the Wisconsin terraces, but it can be traced up to 

 the Illinoian drift border. Reference was made in the discussion of the 

 drift border to a terrace on the lower course of Clear Creek that leads 

 down to the Hocking and also to the old gravel in the Hocking Valley at 

 Lancaster. These seem to be near the head of the glacial drainage. 



The altitude of the gravel terrace decreases in passing down the valley 

 at iabout the rate of fall in the river^ and the terrace .stands 80 to 100 feet 

 above the stream. At Lancaster the gravel has an altitude of nearly 900 

 feet, at Logan scarcely 800 feet, and near Athens about 700 feet above 

 tide. The general elevation is about 50 feet above the terraces of Wisconsin 

 age in the valley. 



The gravel varies greatly in coarseness, some portions being rather 

 fine with a liberal admixture of sand, while other portions are a coarser 

 gravel and cobble. On the whole the material is coarser than is usually 

 displayed by terraces connected witli the Illinoian drift. It is often firmly 

 cemented into a conglomerate, the cement lieing- usually calcareous, but in 

 some cases ferruginous. As noted above, this conglomerate is used at 

 Lancaster in stone fences. Near Logan its outcrops on the face of a 

 terrace bear a strong resemblance to rock ledges. 



Granite, quartzite, and other Canadian rocks, though not so abundant 

 as in the gravels of Wisconsin age, are well represented all along the 

 terrace. Some of these rocks, in a remnant of the terrace near the school- 

 house in the north part of Logan, are .5 or 6 inches in diameter. They are 

 nearly as coarse in the terrace north of Athens. 



In the vicinity of Logan a valley fully one-half mile wide seems to 

 have been filled with this old gravel from a level about 76 feet below the 

 river to a level fully 80 feet above it. For a distance of 3 miles below 



