432 



KIRK BRYAN 



The rocks exposed near the Hot Springs consist of the following, 

 though both older and younger are known in the Ouachita Moun- 

 tains : 



GENERAL SECTION OF ROCKS NEAR HOT SPRINGS, ARKANSAS 



Geologic Age Name of Formation and Description Thickness, Feet 



'Stanley Shale; black, fissile, clay shale, and hard 



compact sandstone 3 , 5oo± 



Hot Springs Sandstone; hard quartzitic lami- 

 nated gray standstone with heavy bedded con- 

 glomerate at the base 200 



Unconformity 

 Arkansas Novaculite; upper half mainly thin- 

 bedded novaculite and black shale; lower half 

 massive novaculite 500=*= 



Unconformityi ?) 

 Missouri Mountain Shale; clay shale generally 

 dark greenish drab to black but red in many 

 places 150 



Carboniferous 

 (Mississippian) 



Devonian 



Silurian 



Ordovician 



Unconformity^ ?) 

 [Polk Creek Shale; black graphitic shale in which 



I graptolites are abundant 200 



iBigfork Chert; thin-bedded gray to black chert 



I much shattered and black shale 700 



The rocks mentioned above were deposited one above the 

 other in great sheets. Since their deposition they have been sub- 

 jected to intense lateral compression which besides lifting the area 

 has produced folds of a general east and west trend. Near the 

 springs these folds have a northeast and southwest trend and the 

 edges of the strata now appear at the surface, and on the map form 

 great looping curves. The major folds consist of numerous smaller 

 folds only a few miles in length, overlapping each other lengthwise. 

 It is with these smaller folds that the springs are associated. 



The structures which have the most to do with theories of the 

 origin of the spring waters are the anticlinal fold whose Hmbs 

 inclose the valley between West, Indian, and Sugarloaf mountains, 

 the synclinal fold of North Mountain, and the anticlinal fold of 



