CARBONIFEROUS FORMATIONS OF THE OZARK UPLIFT 341 



The Coal-Measure shales were deposited in sinks, enlarged joints, 

 and cave-galleries — a fact indicated by their small area and rela- 

 tively great depth. The Knowall Prospect penetrated 85 feet of 

 Coal-Measure shale. Four drill-holes in the immediate vicinity 

 penetrated only the Cambro-Silurian dolomites. x\ shaft in the 

 Gageville Mine passed through 50 feet of Cambro-Silurian dolo- 

 mite and then 10 feet of Coal-Measure shale, the contact being very 

 irregular (Fig. 2). This appears to be a cave-gallery, and may con- 



FiG. 2. — Cave-gallery filled with Coal-Measure Shale, Gageville Mine. 



nect with another shale outcrop in the valley below. Coal-Measure 

 shale occurs in a pocket 50 feet in diameter in a valley at the Son 

 Prospect. On the hillside a shaft passed through 4^ feet of Cambro- 

 Silurian dolomite into the shale (Fig. 3). Further evidence is the 

 fact that the Cambro-Silurian dolomites dip, as a rule, toward the 

 shale outcrops, often as much as 30°. 



Deposition 0} the Graydon sandstone. — The exact time-relations 

 between the Coal-Measure shale and the Graydon sandstone is as 

 yet not certain, but the weight of evidence seems to make the Gray- 

 don sandstone the younger. However, the two may have been 

 contemporaneously deposited in various parts of the country, or the 

 sandstone may have been deposited at two or more times. 



The Graydon sandstone exposures rest on the Burlington lime- 

 stone and on the Cambro-Silurian formations. In the little dissected 

 plain it occurs in many small round areas; in the more dissected 



