GROUND WATER IN NORTH-CENTRAL TENNESSEE

STEATIGEAPHY 57
The Murfreesboro limestone crops out in north-central Tennessee
only at the apexes of small structural domes along the two forks of the
Stone River and within the city limits of Murfreesboro, in central
Rutherford County. (See pi. 4.) Its total outcrop area is about 15
square miles. The exposed beds are about 70 feet thick, although t&e
base of the formation is not exposed and the total thickness is inde­
terminate at the surface.
The test well drilled by the Franklin Oil & Fuel Co. IK miles north
of Murfreesboro (No. 427, pi. 4, and p. 60) has its casing head about
15 feet below the top of the Murfreesboro limestone and passes
through dense bluish-gray and dove-colored limestone to a depth of
285 feet. What portion of these unexposed beds should be correlated
with the Murfreesboro limestone is problematic.
PRE-LOWVLLLE BOCKS OF THE WELLS GREEK BASIN
The group of low rounded hills that coincides with the apex of the
Wells Creek uplift, in southeastern Stewart County (see pi. 4 and pp.
65-67), exposes a light-gray fine-grained slightly cherty limestone of
indeterminate -thickness which Ulrich 21 has called the "Wells chert."
Ulrich states that the "Wells chert" lies beneath the Lowville lime­
stone, though the contact is concealed by detritus, and that its base is
not exposed. Over most of its outcrop this limestone is concealed by
a thick mantle of residual clay and chert, in which most of the chert
fragments are porous or even spongy, soft, and red or brown. In
some places this chert debris is highly fossiliferous, the fauna listed by
Ulrich comprising slender gastropods of the genera Hormotoma, and
Coelocavlus, which are especially abundant, as well as OphUeta,
Helicotoma-, Holopea,.& small Orthoceras that resembles O.primogenium,
a species of Protocycloceras, a slender Scdterella?, Cameroceras sp.,
Cyrtocems cf. confertissimum, Moe&wtw emmonsif, an orthoid similar
to Orthis electra, a striated Syntrophia, and an Isochilina which
resembles I. armata. This fauna is classified by Ulrich as of "Cana­
dian" age, which corresponds to the Beekmantown group of New
York. On the basis of this classification the "Wells chert" seems to
be separated from the overlying Lowville limestone by a stratigraphic
hiatus which is equivalent to the entire Stones River group.
Foerste * refers casually to the " Wells limestone " of the central part
of the Wells Creek Basin but also lists a "Wells" fauna 23 to which he
ascribes an "upper Stones River" age, in seeming conflict with
Ulrich's clasgjfigation.
" Ulrich, E. O., Revision cf the Paleozoic systems: Geol. Soc. America Bull., vol. 22, p. 671, 1911.
88 Foerste, A. F., Silurian and Devonian limestones cf western Tennessee: Jour. Geology, vol. 11, p.
691,1903.
n Idem, pp. 705-706.
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