GROUND WATER IN NORTH-CENTRAL TENNESSEE

j GEOUND WATEE IN NOETH-CENTEAL TENNESSEE
Bucher 24 discriminates two stratigraphic units in the pre-Trenton
rocks of the Wells Creek Basin. The upper unit is possibly as much
as 500 feet thick and comprises strata of dense light-gray and blue
crystalline limestone; it includes at its top the strata of Lowville age
above described. It is much thicker than the Lowville limestone of
the Nashville Basin and may well prove to contain rocks of Stones
Kiver age, as is suggested by Foerste's faunal list. Bucher states that
his collections of fossils have not yet been classified and that it is not
known if they confirm Ulrich's conclusion that the stratigraphic break
between rocks of Lowville age and the "Wells chert" in this district is
equivalent to all the Stones Kiver group. The lower unit, which is
perhaps 200 feet thick, comprises alternating layers of dense light-gray
limestone and crystalline dolomite as much as 30 feet thick. At one
place the dolomite grades laterally into calcareous shale and sandstone
28 feet thick. Bucher classifies this lower unit as of upper Beekman-
town age, in accord with Ulrich's classification.
Exact classification of these pre-Lowville rocks of the Wells Creek
Basin remains a work of the future. Furthermore both the names
"Wells chert" and "Wells limestone" conflict with the firmly estab­
lished Wells formation in the Pennsylvanian of eastern Idaho. In view
of these conditions, these rocks are not named as a stratigraphic unit
in this report and are regarded as of uncertain age, possibly as old as
Beekmantown.
BOCKS NOT EXPOSED AT THE SURFACE
GENERAL FEATURES
The Murfreesboro limestone is the oldest formation that crops out
in the Nashville Basin, and the limestone of Beekmantown (?) age is
the oldest that crops out at any place in north-central Tennessee.
The general character of the underlying strata is disclosed by the fol­
lowing records of two deep wells that have been drilled in the Nash­
ville Basin in search of petroleum. However, there is no sound basis
upon which these records can be correlated with the strata that crop
out in adjacent regions, inasmuch as the unexposed rocks are parted
by at least one major unconformity and can not be differentiated with
certainty by petrographic character.
« Bucher, W. H., The stratigraphy, structure, and origin of Wells Creek Basin: Tennessee Dept. Educa­
tion Div. Geology [in preparation].