86 GEOLOGICAL SURVEY OF ALABAMA 



CLAY COUNTY. 



The mica bearing section of Clay county, which lies 

 within the drainage area of the Coosa and the Tallapoosa 

 rivers, physiographically belongs to the Piedmont Plateau 

 province. 



It is made up of a belt or zone of comparatively narrow 

 ridges, which belt is from six to fourteen miles in width, 

 entering the county from Randolph, near its northeast- 

 erly corner, and extending S. W. for a distance of about 

 25 miles, to the vicinity of Millerville. 



The underlying rocks are mainly schists, gneisses, 

 granites, diorites, phyllites and slates, with infrequent 

 shales and quartzites. 



A dominant structural characteristic of the rocks is 

 their steep angle of dip and frequent faulting. The 

 surface rocks of the micaized zone are highly metamor- 

 phosed crystallines and semi-crystallines, with frequent 

 occurrences and intrusions of diorite and granite dykes, 

 and mainly include feldspathic hydromica schists, 

 muscovite and biotifte micas in pegmatites, an 

 argillaceous mica schist, sericitic, garnetiferous, horn- 

 blendic, graphitic, epidote, and quartz schists; various 

 iron formations, and the Talladega phyllites. Carbonif- 

 erous fossils found on the western edge of the mica zone 

 or belt near Erin*, in the Talladega phyllites, indicate 

 that part of these formations belong to the carboniferous. 



The Hillabee green schist, occurring in the belt north 

 of Delta, is a fine grained rock of olive-green color; in 

 that locality, as elsewhere in the county, carrying numer- 

 ous quartz veins. 



A prevailing characteristic is the breaking down and 

 weathering of the feldspar component of the rocks into 

 kaolin, which has been largely the case but in lesser de- 

 gree with the granites as well as with the pegmatites. 

 Along its western edge, and extending through the coun- 

 ty S. W., the mica belt or zone is bordered by basic and 

 igneous formations; diorites, hornblende, and other fer- 

 ro-magnesium schists, the diorites being largely meta- 

 morphosed. As in Cleburne county, the muscovite mica 



*By Dr. Eugene A. Smith, State Geologist of Alabama. 



