GROUND WATER IN NORTH-CENTRAL TENNESSEE
GROUND WATER IN NORTH-CENTRAL TENNESSEE
GROUND WATER IN NORTH-CENTRAL TENNESSEE
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GEOLOGIC STRUCTURE 65<br />
nooga shale was not deposited across the apex of the dome, that the<br />
lowest beds of the Fort Payne formation rest upon the Hardin sand<br />
stone member with a minor stratigraphic break intervening, and that<br />
therefore folding about this axis began before Mississippian time.<br />
He states further that folding was renewed at a later time, however,<br />
for the Fort Payne formation and overlying bed® of Mississippian age<br />
are deformed nearly as much as the Chattanooga shale.<br />
In the vicinity of White Bluff, in the central-eastern part of Dick-<br />
son County, the strata are arched into one or more anticlines. These<br />
secondary folds have been disclosed by deep wells that penetrate the<br />
Chattanooga shale (pp. 144-145), but they have not been mapped in<br />
detail. They seem to be associated with a marked structural depres<br />
sion in northeastern Dickson County and northwestern Cheatham<br />
County, in which the Chattanooga shale is 50 feet or more below sea<br />
level as indicated by the records of several deep wells. Doubtless<br />
other secondary folds will be found in the area north and west of the<br />
Highland Rim escarpment and within the region covered by this<br />
report when the stratigraphy is traced in detail.<br />
Bassler 33 has pointed out that in many places in central Tennessee<br />
sharp inclinations of the strata are due not to folding or warping of<br />
the crust but to collapse and slumping of strata above caverns formed<br />
by solution. On the Highland Rim plateau features of this sort<br />
exist where solution caverns have formed in the Ordovician lime<br />
stone and the overlying Mississippian strata have collapsed, these<br />
strata being in some places nearly vertical. Bassler points out fur<br />
ther that at some places in the Nashville Basin the topographic<br />
slopes seem to conform to the rock strata, which may rise with the<br />
slope of a hill and descend to its^base on the opposite slope, but that<br />
such features may be due to slump above solution openings rather<br />
than to original structure. Similar features are associated with the<br />
unconformity at the base of the Chattanooga shale, for at several<br />
places in the northern part of the Nashville Basin the Hardin sand<br />
stone member of the Chattanooga fills pre-Mississippian sink holes<br />
30 to 40 feet deep, whereas in adjacent areas the member is less than<br />
a foot thick. A similar feature was noted by Lusk 34 in the Flynn<br />
Creek Basin, in the central part of Jackson County, where the Chat<br />
tanooga shale fills a preexisting sink hole 2 miles in diameter and as<br />
much as 100 feet deep.<br />
WELLS CREEK UPLIFT<br />
In the vicinity of Cumberland City, in the southeastern part of<br />
Stewart County, and the adjacent part of Houston County the strata<br />
M Bassler, R. 8., Sink-hole structure in central Tennessee [abstract]: Washington Aead. Sci. Jour., Vol.<br />
14, p. 374,1924.<br />
* Lusk, R. Q., A pre-Chattanooga sink hole: Science, new ser., vol. 66, pp. 579-580,1927.