GROUND WATER IN NORTH-CENTRAL TENNESSEE

64 GROUND WATER IN NORTH-CENTRAL TENNESSEE
Stone-River about 2 miles northwest of Murfreesboro, near the
apex of a dome about 1% miles in diameter and about 75 feet high.
iFrom this point downstream about 3 miles the river cuts across a
number of small anticlines and synclines which are well exposed in the
river bluffs. Along the east fork of the Stone Elver between Jeffer­
son and Lascassas there are five well-defined domes and several smaller
ones, six of which bring the Pierce and Murfreesboro limestones to
the surface. The largest one is a dome about 3 miles in diameter and
more than 100 feet high just west of Walter Hill. The northeast
flank of this dome is transected by the river, which exposes 27 feet
of the Pierce limestone and 70 feet of the Murfreesboro limestone.
About 2 miles south of Walter Hill is another dome about 2 miles in
diameter and more than 80 feet high. The easternmost of this group
of folds is a double canoe-shaped plunging anticline about 3 miles long,
2 miles wide, and 50 feet high. The town of Lascassas is close to its
apex. The axis of this fold is well defined and strikes about N. 80°
E.; it crosses the principal axis of the Nashville dome. Other
secondary folds within the county are shown on Plate 4.
Secondary folds comparable in size with those of Rutherford
County also occur in other parts of the Nashville Basiny especially
in southern Williamson County. None of them, however, were
mapped in the course of the reconnaissance upon which this report
is based.
On the Highland Rim plateau the rocks are not well exposed and
the structure is generally concealed. In several places where the
plateau has been trenched by streams, however, secondary folds are
also exposed. In the northeastern part of Sumner County five
anticlines and domes from 1 to 2 miles long in the Mississippian rocks
have been mapped by Mather,30 who points out the probability of
other folds in the same district. These folds are more than 20 miles
west of the axis of the Nashville dome.
The Harpeth River gap in southern Cheatham County discloses an
elliptical dome about 4 miles lon^by- 2 miles wide, with about 60 feet
vertical closure as described by Jillson.31 Its southwest flank is
transected by the Harpeth River, and the stratigraphy and structure
are well exposed in the river bluffs and in cuts along the Memphis-
Bristol highway. The major axis of this fold strikes N. 40°-50° W.
and is slightly concave toward the north. At the apex of this fold,
which is about 2 miles N. 30° E. from Kingston Springs, near the
mouth of Dog Creek, the top of the Chattanooga shale is about 650
feet above sea level. Jillson 32 expresses the belief that the Chatta-
* Mather, K. F., Oil and gas resources of the northeastern part of Sumner County, Tenn.: Tennessee
©eol. Survey Bull. 24, pp. 27-30,1920.
* Jillson, W. E., Geology of the Harpeth River area, Tennessee: Oil and Gas Jour., vol. 23, No. 6, pp.
88, 70,1924.
» Jillson, W. E., Unique Devonic sandbar: Pan Am. Geologist, vol. 40, pp. 333-337, 1923.