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Eastern Highland Rim

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About the Eastern Highland Rim

The Eastern Highland Rim is a diverse region covering a large portion of the Interior Plateau, stretching from Kentucky through Tennessee and into northern Alabama.

Terrain here is somewhat diverse, ranging from nearly level in places, to moderately dissected with open hills and knobs in the north, and some areas of karst topography. The bedrock is a mix of chert (a fine-textured sedimentary rock made of quartz) and cherty limestone, with some calicum-rich silicastone, and small amounts of shale and sandstone on higher knobs in the north. Soils here vary by site, but tend to be deep and well-drained. They include both nutrient-rich soils derived from limestone and other calcareous rocks, as well as more leached red clay soils.

The climate is humid and subtropical, with considerable differences in temperature and growing season between north and south. Precipitation is weakly seasonal: in the south, winter brings a long rainy season, whereas in the north, precipitation peaks more briefly in May; throughout the region, late summer to early fall is drier. Winter snowfall is minimal in the south but considerable in the north. The south of this region is subject to greater risk of tornadoes, as well as weakened hurricanes and tropical storms.

This area originally was in a region transitional between oak-hickory forest to the west, and mixed mesophytic forest to the east. The forests here are mostly closer to oak-hickory forest in character, but pure mixed mesophytic forest could be found in ravines in the east of this region. Mesophytic forests included white oak (Quercus alba), hickories, northern red oak (Quercus rubra), southern red oak (Quercus falcata), tuliptree (Liriodendron tulipifera), black oak (Quercus velutina), eastern redcedar (Juniperus virginiana), white ash (Fraxinus americana), and Virginia pine (Pinus virginiana). Floodplains supported a mix of American sweetgum (Liquidambar styraciflua), pin oak (Quercus palustris), red maple (Acer rubrum), eastern cottonwood (Populus deltoides), American sycamore (Platanus occidentalis), common hackberry (Celtis occidentalis), silver maple (Acer saccharinum), elm (Ulmus sp.), and in the south of this region, water oak (Quercus nigra). In the south, there were also some cedar glades or limestone barrens, on areas with exposed limestone bedrock.

Nowadays, this region has a mix of land use, including wild forest, managed woodlands, pastureland, and cropland. The region produces dairy, corn, soybeans, small grains, and hay. There is also oil and gas extraction. Throughout much of the region, flatter uplands tend to be more developed for agriculture, whereas forest cover tends to be highest on the bottomlands and steeper ravines surrounding streams and rivers. However, many of the larger expanses of bottomlands have been flooded by dams. This area is moderately populous, especially in the south, with the largest city being Huntsville, AL, followed by the smaller cities of Decatur, AL, Florence, AL, and Cookeville, TN; there is extensive suburbanization around these cities. There are also numerous smaller towns throughout the region.

This region borders many different regions, owing to its irregular shape that covers a large area. In the north, it is bordered to the west by the Western Pennyroyal Karst Plain, to the northwest by the Crawford-Mammoth Cave Uplands, and to the north by the Knobs-Norman Upland. Over its entire length, it is bordered to the southeast by the rugged Plateau Escarpment, which separates this region from the higher plateaus of the Southwestern Appalachians. This region forms a C-shape around the Outer Nashville Basin, which it surrounds to the south, west, and north. In the south of this region, it is bordered to the north by the Western Highland Rim, to the west by the Transition Hills, and it mostly surrounds an east-west area called Little Mountain. Its southernmost end borders the Dissected Plateau to the south, except for a small area in the southwest where it borders the Fall Line Hills.

References

1. Woods, A.J., Omernik, J.M., Martin, W.H., Pond, G.J., Andrews, W.M., Call, S.M, Comstock, J.A., and Taylor, D.D. "Ecoregions of Kentucky (Poster)", U.S. Geological Survey, Reston, VA (2002) Web.

2. Griffith, G.E.; Omernik, J.M.; and Azevedo, S.H. "Ecoregions of Tennessee (Poster)", U.S. Geological Survey, Reston, VA (1998) Web.