112 
FLORIDA GEOLOGICAL SURVEY—THIRD ANNUAL REPORT. 
nized the effect of local rains on their wells; others who have 
observed less closely recognize no such variation. That the rain¬ 
fall is sufficient to supply the large quantities obtained has already 
been demonstrated. 
FORMATIONS SUPPLYING THE ARTESIAN WATER OF EASTERN 
FLORIDA. 
As explained in the chapter on geology the principal artesian 
reservoir of the eastern part of Florida is the Vicksburg group 
of limestones. In some localities, however, formations lying above 
the Vicksburg group supply a flow, although the flow from these 
more shallow formations is rarely ever so strong as from the 
deeper or Vicksburg limestones. 
DEPTH OF THE ARTESIAN WATER. 
The depth at which the artesian water is obtained is variable 
in different parts of the area. To find the depth for any par¬ 
ticular locality it will be necessary to refer to the subsequent chap¬ 
ters in which the several counties are treated individually. 
COST OF WELLS. 
It has been only within the past few years that artesian wells 
have begun to supplant shallow, Open dug wells in the rural dis¬ 
tricts. One cause of the rapid increase of artesian wells in these 
districts is the necessity of irrigation in order to safeguard truck¬ 
ing and general crops against droughts. Again, from a health 
standpoint, the water from these deeper wells is less liable to 
contamination than is the water from the shallower or surface 
wells. 
The cost of an artesian well depends upon the depth to which 
it is necessary to drill, the size of the well desired, the amount of 
casing used and the character of the material that will probably be 
penetrated in drilling. With a knowledge of the nature of the un¬ 
derlying formations in a given area well drillers know approxi¬ 
mately the time and labor Tt will take to complete a certain size 
well. In such an instance it is frequently the case that a well is 
completed for a stipulated amount regardless of the depth. It is 
more customary, however, to let a contract for a certain size well 
at a given price per foot. These prices vary in different sections of 
the state but on the average two inch wells are sunk for from 
?i.oo to $1.25 per foot; three and four inch wells from $1.50 to 
