Great Sequatchie Valley - Southeast Tennessee
N 35° 22.035 W 085° 19.915
16S E 651539 N 3915047
The Great Sequatchie Valley is located in Southeast Tennesee.
Waymark Code: WM241P
Location: Tennessee, United States
Date Posted: 08/31/2007
Views: 162
Opinions vary on the origins of the Sequatchie Valley. One opinion is that the Sequatchie is a "rift valley". One of only two "rift valleys" in the world, the other being the Great Victoria Valley in Africa, the Sequatchie Valley was formed by giant shears as the plateau literally split apart - giving the valley its memorable shape".
The other theory is that the valley more closely relates to a compressional geologic structure, the Sequatchie Valley anticline.
At the crest of the Sequatchie Valley anticline (an upward fold), Pennsylvanian sandstone was breached by erosion. (This sandstone serves as a resistant cap rock for the plateaus in the Chattanooga area.) The valley was formed by extensive weathering of the underlying Ordovician, Silurian, and Mississippian limestone, which occupies a structurally higher than normal position at the core of the anticline.
"The Tennessee River probably eroded headward across Sequatchie anticline during the Mesozoic and initiated formation of the Sequatchie Valley. Inversion of topography from anticlinal hills and mountains (such as those that persist at both ends of the structure) to the anticlinal valley began when Pennsylvanian formations were breached and the Pennington shales were exposed along the crest of the structure at a level of 4,000 to 5,000 feet above the present valley floor. The valley subsequently developed by headward erosion of drainage tributary to the Tennessee, and by underground solution of structurally elevated limestones where overlying formations were breached.
At the northeast end of Sequatchie Valley (Head of Sequatchie, Vandever quadrangle), the Sequatchie River rises primarily from several springs that have their source in large areas of interior drainage farther to the northeast -- Grassy, Swaggerty, and Crab Orchard Coves, and underground solution and erosion will eventually join the coves to Sequatchie Valley.