1921] 



EDWARDS, SULPHUR MINING ON THE GULF COAST, 



61 



crystallizing of the salt below. Beneath this cap rock is found more 

 limestone impregnated with sulphur and underneath this a bed of gyp- 

 sum resting upon the salt which forms the core of the dome. The sul- 

 phur and the gypsum are derived one from the other but it is not pos- 

 sible to tell which was the original mineral. The sulphur does not occur 



Fig. 33. — The pumps in Plant "C" of the Freeport Sul- 

 phur Co., Freeport, Brazoria County, Texas. 



as a bed but as nodules scattered through the limestone and is present 

 in rather small proportion, making up only 2.7% of the beds in which 

 it is found. The amount of sulphur present varies in different portions 

 of the dome and in different layers of rocks in the same well. So far 

 no wells have been drilled which did not produce some sulphur. The 

 edges of the dome are very abrupt and fall off to an unknown depth. 



