116 FLORIDA GEOLOGICAL SURVEY—THIRD ANNUAL REPORT. 
ing power of water acting along what was the coastal line at the 
time of formation of the strata under consideration. The coarser 
sand particles are dropped near the shore and form the sandstone ; 
the finer sandgrains, together with more or less clay, are carried 
farther out, and form a finer grained sandstone grading ultimately 
Fig- 7 -—Illustrating structures that may prevail in an artesian slope; a. a 
pervious water-bearing stratum which pinches out between impervious strata; 
b. a pervious water-bearing stratum which grades into a less pervious stratum; 
c. a pervious water-bearing stratum in which the artesian pressure is due merely 
to the friction of water moving through the pores of the rock. 
into a clay. Similarly, a sandstone, or other pervious for¬ 
mation, may pinch out as a result of the thickening of a shale or 
clay bed. The term “artesian slope” has been applied to such an 
area to distinguish it from an artesian basin. 
The friction of water threading its way long distances through 
the pores of an inclined pervious formation may result in an 
appreciable artesian pressure. That this is true, may be demon¬ 
strated by the following very simple experiment: Fill a tube 
of any length with sand, and incline at a convenient angle. The 
sand of the tube represents the pervious water-bearing stratum; the 
tube itself, the impervious confining strata. Let smaller tubes 
placed vertically be welded into the larger tube. These vertical 
tubes represent bored wells. The water will be found to rise in 
the vertical tubes, exhibiting an appreciable artesian pressure due 
to the friction of flow through the sand. 
ARTESIAN WATER FROM UNCONFINED HORIZONTAL BEDS. 
It is doubtless possible to obtain artesian water in some in¬ 
stances from unconfined horizontal beds. This condition is illus¬ 
trated by the following sketch taken from the report of M. L. 
