FLORIDA STATE HORTICULTURAL SOCIETY. 
er thickness of later formations rest on 
the peninsular limestone. At Lake Worth 
the limestone is reported at a depth of 
looo feet. A dip to the south is likewise 
indicated from the fact that the peninsu¬ 
la limestone in that direction dips under 
later formations towards Tampa and the 
Manatee region. 
The features of the peninsula area 
1>earing most directly on the question of 
underground waters are as follows: The 
Florida peninsula has as its sub-forma¬ 
tion a porous cavernous limestone. On 
top of this is a varying thickness of sedi¬ 
mentary rocks of alternate pervious and 
imi>ervious layers, limestone, shale, clay 
and sand horizons, and that these hori¬ 
zons dip in general to the east, south, and 
west from the central area. 
Artesian supply: Artesian water is 
properly water confined and under pres¬ 
sure, usually pressure of its own weight, 
so that when the stratum containing it is 
tapped the water will rise in the opening 
thus made. 
Artesian flow occurs when the head is 
sufflcient to cause the rise of water to and 
above the surface level of the mouth of 
the well. 
The conditions necessary to bring 
about artesian water may be grouped for 
brevity under three heads as follows: 
Dip of the strata. 
Alternating impervious and pervious 
strata. 
Some condition or combination of con¬ 
ditions bringing the water under sufficient 
pressure to supply the necessary head. 
This latter condition may result from 
the sagging of a series of these strata at 
the middle allowing the edge to be expos¬ 
ed at either side, so that the water will 
flow at any point lower than the exposed 
119 
area of the horizon. Such a trough like 
structure is an artesian basin. The same 
result may be brought quite as effectively 
by an inclined porous stratum wedging 
out between two impervious strata, or by 
the pervious straum itself grading into 
an impervious or less pervious condition, 
as a sandstone grading into a finer iSand- 
stone, or a sandstone grading into a shale. 
Even a local variation in the thickness or 
texture of the containing stratum may re¬ 
sult in considerable head. The friction 
of water threading its way long distances 
through the pores of a pervious formation 
affords sufficient head for an appreciable 
rise of water through a.boring. (Cham¬ 
berlin, 5th An. Rpt. U. S. G. S., p. 143). 
The term, artesian slope is applied to 
such an area. It is apparent that the 
pressure of the Florida artesian water 
is explained by artesian slope rather than 
an artesian basin. 3 
The dip of the Florida formations 
whatever may have iDeen its cause furni¬ 
shes the first of the essential structural 
features of artesian water accumulation. 
The second condition necessary, the al¬ 
ternating impervious and pervious strata, 
is met in the varied nature of the Florida 
deposits in which water tight clays and 
shales are often succeeded by porous 
and water bearing* limestones and sand¬ 
stones. The head necessary to induce ar¬ 
tesian flow is doubtless due to pinching 
out of strata or change to fine texture of 
the water carrying layer. 
Source of artesian water: 
The catchment area. 
The general gathering ground for the 
artesian water of the coast is naturally the 
interior region of the State. Of the rain¬ 
fall of an area a part is evaporated and re¬ 
turned to the atmosphere; another part is 
carried off immediately to the ocean as 
