UPPER OHIO DRAINAGE SYSTEM. 



89 



yet are located in similar rock formations. The uplands also show an 

 increase in height in passing- down the Ohio from western Pennsylvania to 

 the southern end of the Panhandle near New Martinsville, W. Va., the 

 altitude of local divides between the tributaries in western Pennsylvania 

 being about 1,300 feet, with occasional points 1,400 feet within a few miles 

 back from the river, Avhile in the vicinity of New Martinsville the divides 

 attain an altitude of fully 1,400 feet on 

 the immediate borders of the river and 

 about 1,600 feet within a few miles 

 east. Below New Martinsville the alti- 

 tude declines rapidly, falling to 1,000 

 feet or less in the 50 miles to Marietta. « 



The trend of the tributaries also 

 siTggests a reversal of drainage along 

 the Panhandle. From the most ele- 

 vated parts, near New Martinsville, 

 northward to the end of the Panhandle, 

 they show a decided tendency to point 

 up the valley at their junction with 

 the Ohio, as may be seen by reference 

 to fig. 2. «• 



If, therefore, attention were given 

 simply to altitudes of bordering uplands 

 and to the trend of the tributaries of 

 the Ohio, the old divide would be 

 located near New Martinsville. It was 

 from these criteria that this location of 

 the divide was suggested by Chamber- 

 lin and the writer in 1894.-^ While fig 

 this still appears to have been an early 

 divide, subsequent study of the gradation plains and valley deposits has 

 led to the impression that the divide had migrated before the establish- 

 ment of the present drainage. The gradation plains along the Panhandle 

 show an exceptional intricacy. Instead of a single prominent system of 

 gradation plains, such as is commonly displayed in the Upper Ohio region, 





Scale of miles 



Probable preglaeial drainage of the Upper Ohio 

 region. (Chamberlin and Leverett.) 



' Am. Jour. Sci., 3d series, Vol. XLVII, 1894, p. 253. 



