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Hills of the Bluegrass

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About the Hills of the Bluegrass

The Hills of the Bluegrass are a region of the Interior Plateau located entirely within Kentucky, representing the most rugged of the three bluegrass regions.

This is a hilly region, formed as a dissected plateau, with steeper slopes and more rugged terrain than the bordering bluegrass regions. The bedrock here is mostly calcareous shale, siltstone, and interbedded limestone, with some areas of alluvial, colluvial, and lake sediments, and some loess. Soils here tend to be high in mineral nutrients, but erosion-prone and poor at retaining water. Soils are thin in some areas, and bedrock outcroppings are common. The density of streams here is higher than in the surroundings. Upland streams tend to be intermittent and have rocky bottoms. There are numerous small ponds. Broad bottomlands are limited to areas along the Kentucky and Licking rivers.

The climate here is not appreciably different than its surroundings: it lies towards the cooler end of a humid subtropical climate, with four distinct seasons and a weak seasonality of precipitation, highest in May and lowest in September. However, due to the differences in soil type and drainage structure, the dry season tends to stress plants more here than in the surrounding regions.

This area was originally mostly forested, although its original composition is not well-known. It could have possibly been oak-hickory forest. Dominant species include white oak (Quercus alba), ash, hickory, eastern black walnut (Juglans nigra), black locust (Robinia pseudoacacia), and eastern redcedar (Juniperus virginiana). Drier uplands supported white oak-hickory forest, whereas moister upland sites supported oak-ash forest. Floodplains supported American sycamore (Platanus occidentalis), box elder (Acer negundo), and red maple (Acer rubrum), with an understory of giant cane (Arundinaria gigantea).

This area has been cleared for farmland, but as the soils are more prone to drought and erosion, some have been abandoned. As such there is presently a mix of forest, pastureland, and cropland. Most of the cropland produces hay, but there is some production of tobacco, corn, and small grains on ridgetops. Steeply sloping areas are more likely to have been abandoned by agriculture, but much of this abandonment has occurred recently, and there are many brushy areas in early successional stages of reverting to forest. Most recently-abandoned land supports growth of broomsedge bluestem (Andropogon virginicus) and sumacs (Rhus sp.), which then develops into forest of redcedar and black locust. This area is sparsely populated, and there are no cities, only several small towns, mostly located on the north-south corridor between Lexington, KY and Cincinnati, OH.

In the south, this region mostly surrounds the flatter and more agriculturally-fertile Inner Bluegrass region, except in the east. This region is almost entirely surrounded by the flatter Outer Bluegrass region, except in the south where there is a small border directly with the rugged but geologically-distinct Knobs-Norman Upland.


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.