GROUND WATER IN NORTH-CENTRAL TENNESSEE

STEWABT COUNTY 191
_ In addition to recent alluvial deposits along the major streams,
Stewart County embraces both unconsolidated and consolidated rocks,
which range in age from Upper Cretaceous to Lower Ordovician,
although the full stratigraphic sequence of the Nashville Basin is not
recognized. The unconsolidated deposits include the fine mica­
ceous sands of the Eutaw formation and the underlying chert gravel
of the Tuscaloosa formation, which cover an extensive tract on the
divide between the Tennessee and Cumberland Rivers in the north­
west corner of the county. (See pi. 4.) The Tuscaloosa formation
also occurs in a small area on the crest of the ridge west of Bear
Spring. The youngest of the consolidated rocks are the massive and
medium-bedded St. Louis limestone and Warsaw formation, which
constitute the bedrock over the greater part of the county. Visible
exposures of these beds are uncommon, however, except in the youth­
ful stream trenches, for on all the remnants of the Highland Rim
peneplain the bedrock is covered by 50 to 75 feet of residual clayey
debris. The underlying Fort Payne formation, which in this county
is a dense thin-bedded and extremely cherty limestone, crops out
over the lower valley slopes of the Tennessee River and its tributaries
in the western part of the county, also in the lower part of the Wells
Creek Basin, near the southeast corner of the county. The carbo­
naceous Chattanooga shale underlies the Fort Payne formation and
crops out just above stream level in the Tennessee River Valley at
the mouth of Standing Rock Creek and farther north. It also crops
out as a peripheral band surrounding the Wells Creek uplift and
elsewhere in the Wells Creek Basin. The uppermost of the pre-
Chattanooga rocks, which crop out only in the Wells Creek Basin,
include the Linden formation, of Lower Devonian age, and a rather
full sequence of Silurian limestones. These are in turn underlain by
the Hermitage formation and the Lowville limestone, both of lower
Middle Ordovician age, all Upper Ordovician strata and the upper
part of the Middle Ordovician being absent. The Lowville is under­
lain directly by limestone of earliest Ordovician (Beekmantown?)
age, which is the oldest rock cropping out in north-central Tennessee.
The general character and stratigraphic relations of both the uncon­
solidated and consolidated rocks are discussed on pages 24-58, and their
area! distribution is shown on Plate 4. However, the stratigraphic
relations within the Wells Creek Basin are known only approximately.
Stewart County lies on the flank of the Nashville dome, so that in
general the strata constitute a monocline dipping very slightly north­
westward. In the extreme southeast corner of the county, however,
this regional structure is modified by the Wells Creek uplift (pp. 65-67),
within which the strata are steeply upturned, locally folded, and
complexly faulted.