GROUND WATER IN NORTH-CENTRAL TENNESSEE

66 GROUND WATER IN NORTH-CENTRAL TENNESSEE
are complexly folded and faulted in a manner that is unique for
central Tennessee. The area of deformation covers a roughly cir­
cular area about 8 miles in diameter, and the strata involved range
from the limestone of Beekmantown (?) (earliest Ordovician) age to
the St. Louis limestone. This structural feature is known as the
Wells Creek uplift, from the name of the stream that drains most of
the area of deformation. Its relation to the forces that caused the
upwarping of the Nashville dome and the formation of its superposed
secondary folds is unknown. However, it is possible that crustal
warping began in the Wells Creek area quite as early as in the Nash­
ville Basin, for the Wells Creek section may lack the entire Stones
River group, of Lower Ordovician age (pp. 57-58), and lacks much
of the Middle Ordovician and Upper Ordovician (Richmond) group.
The unique structure of the Wells Creek uplift was first recognized
by Safford,35 who pointed out that the strata in the center of the de­
formed area are older than any other rocks exposed in central Ten­
nessee and that they dip vertically or at high angles. Safford inter­
preted the structural feature as a high dome, with the strata cropping
out in successive bands concentric about the apex of the dome and
dipping away from the center of the basin. He also pointed out
that the Mississippian rocks are both folded and faulted for several
miles away from the area of intense deformation, as is exposed in
the bluffs of the Cumberland River several miles upstream and
downstream from Cumberland City.
Jillson 36 has pointed out certain similarities of the structure of the
Wells Creek uplift to that of Jeptha Knob, in Shelby County, Ky,,
and Serpent Mound, in Adams County, Ohio. He assumes that all
these features are contemporaneous and concludes that they were
produced by forces transmitted by a body of igneous magma a few
thousand feet beneath the surface.
Very recently Bucher has started to map the structure of the
Wells Creek uplift in detail. His prelimininary report 37 is abstracted
in the following paragraphs:
Topographically the Wells Creek Basin is an elliptical depression
in the Highland Rim plateau (pp. 16-18) bounded on all sides by an
erosion scarp 225 to 275 feet high. This depression is about 2% miles
long and 2 miles wide, and the longer axis trends nearly due north.
The floor of the basin comprises three topographic units, which are
also stratigraphic and structural units. These are a central hill,
which is rudely circular, 2,700 feet in diameter, and about 80 feet
high; a ringlike lowland plain 1,500 to 3,500 feet wide surrounding
the central hill; and a belt of foothills 1,500 to 2,000 feet wide sur-
» Safford, J. M., Geology of Tennessee, pp. 147-148, Nashville, 1869.
» Jillson, W. B., An isothrustic hypothesis: Fan Am. Geologist, vol. 40, pp. 251-268,1923.
w Bucher, W. H., The stratigraphy, structure, and origin of Wells Creek Basin, Tennessee: Tennessee
Dept. Education Div. Geology (in preparation).