WATER SUPPLIES AND WELL RECORDS. 



109 



substructure is an important element in formulating the geologic 

 history of the land area and hence has the same broad and general 

 application as other geologic studies, having both an economic 

 and educational value. 



As an instance of a well from which an approximately com- 

 plete record has been obtained may be mentioned the City well 

 at Jacksonville in Duval County drilled in 19 10, the record in 

 this case being supplied through the courtesy of the drillers, the 

 Hughes Specialty Well Drilling Company. This well reached a 

 total depth of 980 feet, and samples of the drillings were kept at 

 occasional intervals, a total of 46 samples having been preserved 



Fig. 26. — Well drilling machinery used in Florida. 



and submitted to the State Survey. The detailed log of the well 

 based on an examination of the samples supplemented by the 

 notes made by the driller has been published in the Fifth Annual 

 Report of the Survey, and need not be repeated here. The prin- 

 cipal water supply in this well is obtained from the Vicksburg 

 limestone, a formation well known to the drillers as it is the chief 

 water bearing formation of the peninsular section of the State. 



The first flow of water amounting to only about 5 gallons per 

 minute was obtained in this well at a depth of 270 feet. At the 

 depth of 493 feet the flow was increased to 112 gallons per minute, 



