A NATIONAL PLAN FOR AMERICAN FORESTRY 



379 



comes more broken and hilly and differences in elevation of 100 to 

 300 feet in rather short distances are common. Along the Ohio River 

 itself, steep bluffs and highly dissected topography are found from 

 Pittsburgh down to about 50 miles below Louisville, Ky. Within the 

 bluegrass country of Kentucky and the central basin of Tennessee the 

 surface is rolling, but both of these localities are enclosed by rims of 

 higher steep hilly land called the Knobs in Kentucky and the High- 

 land Rim in Tennessee. In the southwestern portion of the basin, 



iELATIVE INFLUENCE OF FORESTS 

 ON WATERSHEDS 



MAJOR INFLUENCE 

 MODERATE INFLUENCE 

 SLIGHT INFLUENCE. 



FIGURE 9. Ohio River Basin. 



on the low^er stretches of the Tennessee and Cumberland Rivers, roll- 

 ing to hilly land is found which in places is comparatively rough. 



The southeastern and eastern portions of the Ohio Basin are 

 decidedly mountainous in character. They include three distinct 

 provinces, the Blue Ridge, the Appalachian Valley, and the Appa- 

 lachian Plateau. The Appalachian Valley separates the other two 

 provinces and drains to the southwest as part of the Tennessee River 

 Basin. Within the valley are found long parallel steep-sided moun- 

 tainous ridges. The Appalachian Plateau to the west includes the 

 Cumberland Plateau of eastern Tennessee and Kentucky and the 

 Allegheny Plateau north of the Kanawha River in West Virginia and 

 Pennsylvania. 



