138 



SOUTHERN APPALACHIAN REGION. 



beneath the surface at vaiying but generally steep angles. 

 The southern half of the region has along its western 

 boi-dcr an irregular belt of bedded slates, limestones, 

 quartzites, and conglomerates. These rocks, which make 

 up the great bulk of the surface, have a general north- 

 easterly stx'ike and a steep but varying dip; while near the 

 eastern border there is another, liut narrow and more irreg- 

 ular, belt of rock of somewhat similar character, which 

 follows approximately the general position of the Blue 

 Ridge, and dips steeply southeastward. 



As stated above, the important streams rising in 

 Virginia, the Carolinas, and Georgia have their origin on 

 the slopes of the Blue Ridge. Those rising on the eastern 

 slope, such as the James, Roanoke, Yadkin, Catawba, 

 Broad, Savannah, and Chattahoochee, flow generally toward 

 the southeast, their head streams plunging down the moun- 

 tain slopes many hundreds of feet in short distances and 

 soon reaching the gentle slope of the Piedmont Plain. (See 

 Pis. XXVIl and LXX.) The streams rising on the west- 

 ern slopes of the Blue Ridge — the Watauga, Nolichucky, 

 French Broad, Pigeon. Little Tennessee, Tuckasegee, and 

 Hiwassee rivers — flow in the general characteristic north- 

 westerly direction across the upturned ridges of the gneiss 

 and more I'ecent bedded rocks, with frequent falls, into the 

 great valley of East Tennessee. (See PI. LXXI.) The 

 Holston River, which flows along this valle}^ from its upper 

 end to its junction with the Tennessee system, forms an 

 exception to the general direction of flow in this region, 

 for its course lies toward the southwest; and the Coosa 

 ' River, of Alabama, which has its headwaters on the south- 

 eastern slopes of the Blue Ridge, takes a similar direc- 

 tion. The New River, also, which rises in the cross ranges 

 connecting the Unakas and the Blue Ridge, flows toward 

 the northwest into the Ohio. The elevation of the coun- 

 tr}^ is so great and the descent of the stream is so rapid 

 that the general course of the principal rivers has been but 

 little modified by the geologic structure of the region, 

 though the}^ lie directly across the strike of the rocks. 

 The resulting conditions produce occasional falls and cas- 

 cades in the streams (see PL LXX VII); but the larger 

 part of the courses of these streams consists of a succession 

 of rapids (see PI. LXXIII), furnishing ample opportuni- 

 ties for water-power development hy the building of dams 

 at intervals across the deep, nari'ow gorges. A number 

 of the smaller tributar}' streams in North Carolina and in 



