6 BUREAU OF AJVIERICAN ETHNOLOGY [Bull. 182 



bottom and valley walls. Long ridges extend from the upper valley 

 walls to high ground east and west of the damsite. The ridges are 

 composed almost entirely of residual soil and decomposed rock, with 

 sound rock present at considerable depth. 



The Ked Oak Granite formation, within which the entire damsite 

 is located, is classed petrographically as a biotite-quartz monzonite. 

 However, the rock has many variations that have been observed 

 throughout the reservoir area. Facies of the rock have been examined 

 with variations from granite through a strongly banded biotite gneiss 

 to a heavily contorted schistose structure. One small locality near 

 the western end of the left-wing dike is underlain by a light-green 

 hornblendic to chloritic gneiss that has been weathered and fractured 

 to depths in excess of 100 feet. 



TOPOGRAPHY 



The John H. Kerr Reservoir area lies wholly within the Piedmont 

 Plateau, and presents the topographic features common to that 

 physiographic province. The topography is mature, the hills well 

 rounded, and relief is much subdued. In fact, there is little relief 

 noticeable to the casual observer, except where streams cut through 

 the Virginina ridge, a low-lying, nearly flat-topped ridge with very 

 gentle slopes, which forms the most prominent surface feature of the 

 district. The most marked relief is along the Dan River, which 

 crosses the district near its center. This stream crosses the rocks 

 approximately at right angles to the strike of the schistosity, and, 

 where it cuts through the Virginina ridge, the slopes are steep and 

 the topography is rather rugged. The remainder of the district is 

 without prominent relief, but is decidedly hilly. 



DRAINAGE 



The Dan River flows in a southeasterly direction across the center 

 of the district. Within the area the Dan is joined from the north by 

 the Banister and Roanoke Rivers, and from the south by the Hyco 

 River and Aarons Creek. The Roanoke receives Horscpen Creek 

 from the east, and Difficult Creek from the west, while Hyco receives 

 Blue Wing and Mayo Creeks from the east. These make up the prin- 

 cipal streams, but rainfall during certain portions of the year is very 

 hea\7 and smaller streams are numerous. The larger streams, especi- 

 ally Dan and Roanoke Rivers, hold their course regardless of the 

 character of the underlying rocks, but the creeks and smaller streams 

 are greatly influenced, if not controlled, by it. Rainfall, especially 

 during the winter and spring months, is hea^T", and for the most part 

 the district is well watered. 



