no FLORIDA GEOLOGICAL SURVEY SIXTH ANNUAL REPORT. 



the water having as it flowed from the pipe a temperature of 71 

 degrees F. Upon entering the Vicksburg limestone which was 

 reached in this well at 510 feet the flow was increased to 200 gallons 

 per minute. The inner casing was rested upon this limestone, the 

 drill hole being continued into this formation 470 feet or to a total 

 depth of 980 feet. As the deeper strata of the Vicksburg limestone 

 were penetrated the amount of flow, the pressure and the tem- 

 perature increased. At 625 feet the flow amounted to 500 gallons 

 per minute, having a temperature of 74 degrees F. At 6S0 feet 

 the artesian pressure at the surface was 12 pounds per square inch, 

 indicating a head above the surface of 27.7 feet. At 780 feet the 

 flow from the well was about 900 gallons per minute, and the pres- 

 sure 15 pounds per square inch indicating a head above the sur- 

 face of 34.6 feet. The flow in the completed well at a depth of 

 980 feet was between 1500 and 2000 gallons per minute. 



Through the records kept by the Superintendent of the City 

 Water Works, something is known also of the flow of several wells 

 at Jacksonville through a period of twenty years. These records 

 were also included in the Fifth Annual Report of the Survey. 

 Wells, the flow of which was measured, show a reduction in flow in 

 a period of ten years to about one-fourth of their original efficiency. 

 Another well of which a very satisfactory record has been ob- 

 tained is one drilled recently by F. S. Gilbert at Tiger Bay in 

 Polk County, the samples and records being supplied through the 

 courtesy of the owners of the well, the Palmetto Phosphate Com- 

 pany. This well has a depth of 838 feet, and samples were taken 

 with some exceptions at ten foot intervals, a total of 6j samples 

 having been preserved. These were forwarded to the State Geo- 

 logical Survey, and the detailed log made from the samples, supple- 

 mented by the notes of the driller, will be published in the subse- 

 quent reports of the Survey. After passing through the surface 

 materials at this locality the drill penetrated sandy phosphatic 

 marls to the depth of 360 feet. The material throughout this whole 

 thickness, while by no means uniform apparently represents a single 

 geologic formation which is locally variable. The phosphatic 

 pebbles which occur throughout the whole thickness are black, brown 

 or white in color and are rounded smooth and shiny, the larger 

 pebbles being often pitted. The pebbles are imbedded in marl, the 

 prevailing color of which is light buff or grayish. The marl is 



