GROUND WATER IN NORTH-CENTRAL TENNESSEE

ARTESIAN CONDITIONS 97
may be expected is limited to bottom lands and low terraces along
the Cumberland Kiver and its tributaries in the vicinity of Nashville.
However, the exact altitude and inclination of the pressure-indicating
surface (the imaginary surface to which the ground water would rise
in a well) are not known, so that this area can not be bounded specifi­
cally. It probably extends several miles both upstream and down­
stream from Nashville. As is shown by analyses of samples from
weUs 295 and 298 (pp. 114-115), the water from the St. Peter (?) sand­
stone in this district is rather highly concentrated in dissolved mineral
matter and contains considerable hydrogen sulphide gas in solution.
The chemical character of much of the water renders it undesirable
for domestic consumption and many other purposes. Futhermore,
the specific capacity of the wells that enter this stratum or strata
seems to be relatively small, being less than 10 gallons a minute for
each foot of drawdown, although the casings are in poor condition,
so that data adequate to determine the specific capacity exactly are
not obtainable. Hence, large yields may not be obtainable from the
St. Peter (?) sandstone even by pumping. The St. Peter (?) sand­
stone seems to thin rapidly toward the southeast, for its horizon in
the Franklin Oil & Fuel Co.'s test well at Murfreesboro, Kutherford
County, seems to be represented by calcareous and magnesian sand­
stone about 10 feet thick (p. 60). Furthermore, it becomes imper­
meable in the same direction. The horizon of the St. Peter (?)
sandstone is not known to be reached by wells in other directions
from Nashville, so that its water-yielding capacity and the static
level of its water are unknown. Although this stratum may hold
water under sufficient head to overflow at the surface in other parts
of north-central Tennessee, its depth below the surface increases
radially outward from the apex of the Nashville dome (pp. 62-63);
hence the cost of drilling wells to the stratum will increase accordingly.
This fact, coupled with the chemical character of the water and the
small specific capacity of the wells at Nashville, will probably make
it uneconomical to develop this water-bearing formation for many
purposes.
Water under artesian head also occurs on the flanks of the White
Bluff dome of Dickson County (pp. 140-142), as in wells 206, 216, 220
(pp. 144-146), and several other deep wells of that locality. It is
reported by drillers and others that the water occurs in the uppermost
layers of the Chattanooga shale, although that formation is generally
quite impermeable where it is not weathered. It is more probable that
the water-bearing stratum is a permeable sandstone or a channeled
Umestone that overlies or underlies the Chattanooga shale. The water
contains only a moderate amount of dissolved mineral matter and a
slight amount of hydrogen sulphide, although its noncarbonate or