GROUND WATER IN NORTH-CENTRAL TENNESSEE

SURFACE FEATUKES OF CENTKAL TENNESSEE 23
upstream. The lower reaches of its major tributaries, the Harpeth
and Stone Rivers, have kept pace with the downcutting, although
the trenching dies out upstream and the heads of the streams flow
on the Nashville Basin peneplain. The meandering portions of the
stream courses are now somewhat ingrown, with gravel-veneered
slip-off slopes on the inner sides of the meanders, but the linear
reaches of the streams have merely deepened their channels;without
lateral planation. Hence the present erosion cycle is clearly in a
very youthful stage.
DRAINAGE SYSTEM
SURFACE STREAMS
The surface waters of north-central Tennessee are all drained into
the Gulf of Mexico by way of the Mississippi River. The immedi­
ate master streams, however, are the Tennessee, Cumberland, and
Green Rivers, tributaries of the Ohio River. (See pi. 3.)
The Tennessee River rises in the Valley and Ridge province in
extreme southwestern Virginia and follows that physiographic prov­
ince southwestward to Chattanooga. Thence it swerves westward
across northern Alabama and northward, nearly in the opposite
direction from its upstream course, entirely across Tennessee and
enters the Ohio River in western Kentucky about 50 miles above the
junction of that stream with the Mississippi. The western limb of
the Tennessee River bounds the region covered by this report on the
west. The Duck River, the only noteworthy tributary of the Ten­
nessee within the region, heads on the Nashville Basin peneplain and
flows westward and northwestward across southern Humphreys
County.
The Cumberland River rises on the Cumberland Plateau in south­
ern Kentucky and follows a tortuous course westward across north-
central Tennessee, swerves northward at Dover and flows parallel to
the Tennessee River into Kentucky. It joins the Ohio River about
70 miles above its mouth, or 20 miles above the Tennessee River.
The two largest tributaries of the Cumberland from the south, the
Stone and Harpeth Rivers, head on the Nashville Basin peneplain
in Rutherford and Williamson Counties and flow northwestward to
the major stream. The Red River, which enters the Cumberland
from the northeast at Clarksville, drains a considerable portion of the
northern Highland Rim plateau.
The Green River rises on the Highland Rim plateau in north-
central Tennessee and central Kentucky and flows northwestward
to its junction with the Ohio River. Its headwater tributaries drain
the extreme northeast corner of the region covered by this report and
portions of the adjoining counties of Macon and Clay.