54 



RESOURCES OF TENNESSEE. 



highland surface as a plain that in many places is well developed and of 

 broad extent, as for instance, about Tullahoma, McMinnville, Clarksville, 

 and Dickson. The edges of the rim surrounding and overlooking the 

 Central Basin are usually intimately dissected into steeply-rounded hills 

 and spurs that form one of the roughest parts of the Highland Plain. An- 

 other portion of the plain that is well dissected by streams is the part just 

 east of the Tennessee River in Hardin, Wayne, Perry and adjoining coun- 

 ties. Erosion here has usually been not more than 100 or 200 feet in 

 depth, and even the worst eroded part of the region presents no such ob- 

 stacles to travel and free communication as are presented by the deeply 

 dissected portions of the Cumberland Plateau. 



FIG. 4. View from Sunset Rock, Monteagle, looking north. Shows spurs from 

 the Cumberland Plateau, jutting out on the Highland Plain. 



Influence of geology on topography and soil. The general surface of 

 the Highland Plain is somewhat complex in its geology, and this has re- 

 sulted in certain differences in topography and soil that have had a more 

 marked influence in the development of the plain than any other. A part 

 of the surface is underlaid by the St. Louis limestone and has the rolling 

 topography usually characteristic of limestone solution surfaces. It also 

 has the good soils that are usually an additional characteristic of such 

 regions. A second part of the plain has a siliceous shale as its underly- 



