GROUND WATER IN NORTH-CENTRAL TENNESSEE

RUTHERFORD COUNTY 179
water table after channeling. Consequently, there seem to be no
extensive systems of solution channels underlying those which are
adjusted to the present surface streams, and thus the limestones are
generally not water bearing where they lie at more than moderate
depth.
Over much oi the peneplain the unweafchered rock lies very close to
the surface, so that dug wells do not furnish adequate supplies of
water. At most places, however, drilled wells obtain sufficient water
for domestic purposes and for stock. The water-bearing beds range
from 40 to 135 feet below the surf ace, though generally from 60 to 100
ieet. The depth oi water-bearing beds may differ greatly in wells
which are close together. Some wells, such as Nos. 432, 434, 437, 440,
and 441 (pp. 184-186), penetrate water-bearing beds from 175 to 250
feet below the surface, but others of similar depth are dry holes.
Well 423, for example, did not reach a water-bearing bed, though
drilled to a depth oi 446 feet. In the vicinity of Murfreesboro wells
434, 440, and 441 seem to obtain water at about the same stratigraphic
horizon, from a bed oi soft granular limestone 200 to 245 feet below
the surface and about 350 to 375 feet above sea level. This bed seems
to differ greatly in water-yielding capacity from place to place,
however, so that it can not be assumed to be water bearing in all
parts of the county. Most of the drilled wells are used for domestic
purposes only; hence they are pumped intermittently and lightly,
and their total capacity is not known. In fact, relatively few of the
wells have proved capacities of more than 5 gallons a minute. On the
other hand, wells 435,440, 441, and some others that chance to enter
large solution channels yield 100 gallons a minute or more, although
the capacity of such wells is likely to vary greatly from season to
season or even to vary with local precipitation. These wells are
drilled in cavernous limestone at or near the orifices of large tubular
springs.
The St. Peter (?) sandstone (p. 61) has been considered a poten­
tial water bearer throughout north-central Tennessee. It seems to
correspond with sandy beds that were entered about 610 feet below
the surface in the Franklin Oil & Fuel Co.'s test well near Murfrees­
boro (No. 427, pp. 60-61), and its projected horizon is penetrated by
well 4 of the Carnation Milk Products Co.'s plant (No. 433, p. 184).
However, neither oi these wells is reported to have found an appreci­
able amount of water at this horizon. It is probably inadvisable,
therefore, to drill to this formation ior ground water in other parts of
the county.
In general, it is not to be expected that large yields of water can be
obtained in Rutherford County from wells. For example, of four
wells drilled in 1927 at the plant of the Carnation Milk Products Co.,
near Murfreesboro, only one was moderately successful. This well,