THE ARTESIAN WATER SUPPLY OF EASTERN FLORIDA.

this well was takenJanuary io, 1910, and was found to be i pounds. The elevation of the well is approximately 8 feet above the River. This, together with a pressure of 15 pounds
would give the well a head of 42.65 feet above the level of the water in the St. Johns River.
RIVERDALE.
Riverdale is a settlement along the St. Johns River in southwestern St. Johns County. At this place several artesian wells have recently been drilled. A well 302 feet deep was sunk in 1909 by Mr. R. C. Walker for the Riverdale Land Company. This is a sixinch well and is cased io7 feet. The well is reported to have a head of 33~2 feet above the surface and the surface elevation above the St. Johns River is estimated to be 8 feet which gives the well a total head of 41 2 feet. The first rock encountered was at a depth of 175 feet and at this depth the water was found to be under sufficient pressure to rise to the surface. An increase in the flow of water was reported at a depth of 190 feet.
Mr. R C. WValker completed on February I, 19io, a well for Mr. J. D. Clark. This well is six inches in diameter, 318 feet deep and is cased 136 feet. At the depth of 174 feet a one foot stratum of bluish clayey limestone was encountered. An increase in water is recorded at the depth of 200 feet, from which depth the first flowing water is reported(. The well samples indicate that this flow comes from a very hard bluish colored rock and water worn small pebbles. Immediately on passing through this stratum which was 19 feet in thickness, the Vicksburg ILimestone was reached as is shown by the presence of Nunmulites. This determination was made from a very complete set of samples of the drillings from this well kindly saved by the driller, Mr. R. C. Walker. This limestone was penetrated for nearly Ioo feet, the total depth of the well being 318 feet. The following is a log of this well constructed from the notes and the samples sent in by Mr. Walker.
Feet.
Surface sand, yellow in color. Soft water................... o- 18
Light gray sands ........................................ 18- 30
Dark gray sands, partly induirated; some clay................... 30- 44
Shell, sand and gravel .................. ........................ 44- 5'
Very dark (almost black), marl, similar in appearance to Miocene
marls, including shell fragments .......... .......... 55- 63
Light greenish sandy marl ............................63- 8o
Dark green marl, small shark's tooth observed................. 8o-loo
Gray sand and shell fragments; water .................. IOO-ii2

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