Highland Rim
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The Highland Rim is a geographic term for the area in Tennessee, North Alabama, and Kentucky which surrounds the Central Basin. Geologically, the Central Basin is a dome. The Highland Rim is a cuesta surrounding the basin, and the border where the difference in elevation is sharply pronounced is an escarpment.
Geology and Physiography
The Highland Rim is a
The sections of the Highland Rim are referred to the four cardinal directions, e.g., "Northern Highland Rim", etc. The Highland Rim is rather continuous and any division of it, including the ones made below, are somewhat arbitrary. The term "highland" here is relative: it is certainly higher than the basin it surrounds, but it nonetheless is seldom at an elevation above 1,100 feet (340 m) above sea level and never more than about 1,400 feet (430 m) above sea level except where interrupted, primarily to the southeast, by outliers of the Cumberland Plateau. With the exception of a few broad stream bottoms, the land is characterized by ridges and valleys with a few fairly low hills. The entire region is well watered with many perennial streams. There are occasional waterfalls which sometimes delineate the Highland Rim from the Central Basin which it surrounds.
Western Highland Rim
The Western Highland Rim is encountered a few miles west of Nashville and extends to the western valley of the
Eastern Highland Rim
The Eastern Rim rises approximately fifty miles east of Nashville and is bordered to its east by even higher terrain, the Cumberland Plateau. Erosion has exposed carbonate bedrock of Late Paleozoic age. These carbonate rocks contain variable amounts of chert and are often interbedded with fine grained clastic rocks. As a result, these rocks are more resistant to erosion than the underlying purer limestones of the Lower (Early) Paleozoic. The geology is diverse and is
typically limestone at valley floors (around 500 feet (150 m) elevation) and sandstone on ridges (to around 1,000 feet).
Northern Highland Rim
The Northern Highland Rim is encountered a few miles north of Nashville and extends to the Kentucky border, and the region of Kentucky adjacent to it called the Pennyroyal is largely a continuation of it under another name.
Southern Highland Rim
For the most part the Southern Rim is the farthest from Nashville, rising at some points just a few miles north of the border with Alabama. The landforms are continuous with those in adjacent portions of Alabama, although perhaps the most spectacular landforms of any portion of the Rim are to be found there.
The stratigraphy of the Southern Highland Rim is primarily composed of flat-lying limestones, dolomites, and shales, and to a much lesser extent, of cherts, siltstones, mudstones, and very fine grained to conglomeratic sandstones.
References
- ^ "Physiographic divisions of the conterminous U. S." U.S. Geological Survey. Retrieved 2007-12-06.
- ^ a b "Physiography of Tennessee". Tennessee Archaeology Net. Archived from the original on 2007-11-06. Retrieved 2007-12-30.
- ^ Shofner, Gregory A.; Hugh H. Mills; Jason E. Duke (2001). "A Simple Map Index of Karstification and its Relationship to Sinkhole and Cave Distribution in Tennessee" (PDF). Journal of Cave and Karst Studies. Archived from the original (PDF) on September 25, 2006. Retrieved 2007-12-30.
- ^ "Alabama Comprehensive Wildlife Conservation Strategy" (PDF). Alabama Department of Conservation and Natural Resources. Archived from the original (PDF) on 2008-04-09. Retrieved 2007-12-30.