MAP AND CHART 187 KENTUCKY GEOLOGICAL SURVEY SERIES XII, 2008 James C. Cobb, State Geologist and Director Elevation (feet) Slope UNIVERSITY OF KENTUCKY, LEXINGTON Outer Bluegrass 257* 500 *excluding quarry pits Level to rolling Inner Bluegrass 500 750 Rolling to hilly 750 1,000 Hilly to steep BLUEGRASS REGION Kentucky Terrain 1,000 1,500 Very steep 1,500 4,111 The Bluegrass Region is bounded by the Knobs and the Ohio River. Bedrock in most of the region Daniel I. Carey and Terry D. Hounshell is composed of Ordovician limestones and shales 450 million years old. Younger Devonian, Silurian, and Mississippian shales and limestones lie beneath the perimeter of the region. Much of the Ordovician 10 0 10 20 30 40 Miles strata lie buried beneath the surface. The oldest rocks at the surface in Kentucky are exposed along N the Palisades of the Kentucky River. Limestones are quarried or mined throughout the region for use 10 0 10 20 30 40 50 Kilometers in construction. Water from limestone springs is bottled and sold. The Bluegrass, the first region settled by Europeans, includes about 25 percent of Kentucky. Over 50 percent of all Kentuckians live there an average of 190 people per square mile, ranging from 1,750 people per square mile in Jefferson County to 23 people per square mile in Robertson County. terrain: the physical features of a regionslope, down quickly when exposed to air and water. elevation, landforms, geology Areas dominated by sandstones and siltstones SubregionDominant Rock Type tend to have hills with steep sides. As the shale Inner Bluegrass Regionlimestone Bluegrass Region Knobs Pine 22 Eastern Kentucky Coal Field The Inner Bluegrass is characterized by rich, fertile The terrain of Kentucky has been shaped by content increases, the landscape becomes more Jackson Purchase Western Kentucky Knobs and Mountain phosphatic soils, which are perfect for raising thor- Region Pennyroyal Coal Field Pennyroyal and Shale Belt (Appalachian Basin) Porous limestone in the Inner Bluegrass is laced with solution 21 (Mississippi Embayment) (Illinois Basin) Shale Belt A oughbred horses. The gently rolling topography is geologic forces and the underlying rocks. Tectonic rounded, with wide stream valleys. Areas under- Region Region channels, cracks, and crevices. Contaminated water and septic Cincinnati caused by the weathering of limestone that is typical Pine Mountain Overthrust Fault Lexington Fault System A Kentucky River Fault System Rough Creek Fault System Arch effluent can travel quickly through underground openings and Shaly limestone typical of the Outer Bluegrass is exposed in a roadcut forces lifted, bent, and buckled the rocks Fault System Tabb lain by limestone may have few surface streams pollute surface and groundwater. of the Ordovician strata of central Kentucky, pushed along Ky. 646 in Montgomery County. The terrain of the Outer Bluegrass originally formed from sediments on shallow sea (karst topography) and gently rolling land. As the up along the Cincinnati Arch. Weathering of the lime- is, in general, more rolling than that of the Inner Bluegrass. The shale floors or swampy lowlands. Weathering and stone also produces sinkholes, sinking streams, impedes underground flow and there are fewer sinkholes. shale content in the rocks increases relative to Palisades springs, caves, and soils. A erosion shaved the hills and dissected the plains, limestone, the land becomes hillier. How the bending, warping, and erosion of layers of rocks causes them to occur at the surface in illustration not to scale A Outer Bluegrasslimestone and shale some parts of the state, but deep beneath the surface in other areas. exposing at the surface a cross section of rocks Natural resourcescoal, oil, natural gas, soils The Outer Bluegrass is mostly composed of inter- 250 to 500 million years old. The sands, gravels, bedded Ordovician limestones and shales that are are the products of geologic history and vary more easily eroded than the limestones of the Inner silts, and clays of the Jackson Purchase Region from region to region. In turn, the ecology and Bluegrass. It is less karstic, with fewer sinkholes are younger, remnants of a time when the sea and rolling hills. The shales impede the flow of economy of the different regions of Kentucky groundwater, and there are fewer springs and wells. lapped at the confluence of the Mississippi and are distinctive. WESTERN KENTUCKY The topography of the Western Kentucky Coal Field ranges from nearly level Ohio Rivers. bottomlands to forested hills. The poorly drained floodplains and terraces along Bluegrass HillsShaly limestone To learn more about the rocks and terrain typical COAL FIELD the Ohio River and the wide valleys of the interior streams are underlain by loess, Shale is more dominant in the Bluegrass Hills. The The landforms in Kentucky are the result of the sand, silt, clay, and gravel. Outside the valleys, low hills predominate, underlain land is hilly, with limited agriculture. Slope stability of your area, find the region you live in on the may be a problem in development, particularly in differential weathering of interbedded sandstones, by 300-million-year-old Pennsylvanian shale, sandstone, siltstone, limestone, 19 map and then go to the associated text and coal, and underclay. Around the boundary of the region the valleys are the Greater Cincinnati area. siltstones, shales, and limestones. Sandstones narrower and the terrain more rugged, with hills capped by erosion- The Outer Bluegrass terrain, as typified in central Washington County, provides rich soils picture group for that region (color-coded frame for agriculture, attractive sites for rural residential living, habitat for wildlife, and industrial and siltstones resist erosion, limestones dissolve resistant sandstone. Eight percent of Kentuckians live on the 20 18 sites. and header block matches the map region color). 12 percent of Kentucky that is the Western Kentucky Coal along cracks and crevices, and shales break Fieldabout 60 people per square mile. The Knobs consists of hundreds of isolated, steep-sloping, often cone- Inner BluegrassLimestone in the Bluegrass provides rich shaped hills lying at the outer edge of the Bluegrass Region. The hills are soils and level terrain, spring-fed ponds, and rock for con- monadnocks or erosional remnants that were originally part of the Missis- struction. Mile after mile of historic stone fences made from Regional and subregional delineations For information on obtaining copies Explanation for primary map in center of this map and other Kentucky sippian Plateau (Pennyroyal Region), but were separated from the plateau local limestone by Irish immigrant stonemasons grace the of map sheet adapted from GIS data developed by Geological Survey maps and by stream erosion. Many of the knobs are still capped by erosion-resistant highways and byways of the Bluegrass. William Andrews, Kentucky Geological publications call: limestones or sandstones. The sloping sides of the Knobs are mostly Survey. Alluvial valley Public Information Center composed of shales of the 350-million-year-old Mississippian Borden Bluegrass Hills (859) 257-3896 ext. 126 SubregionDominant Formation, which are more easily eroded than the overlying limestones Thanks to Kim and Kent Anness, Kentucky Newport The bedrock of the Bluegrass Hills has a higher Bluegrass Region Toll free: (877) 778-7827 ext. 126 Rock Type and sandstones. The Knobs are associated with the outcrop belt of Silurian COVINGTON Dayton Division of Geographic Information, for base and Devonian black and clay shales. Bernheim Forest (south of Louisville) shale content than that of the Inner and Outer map data. Fort Thomas Bluegrass. The shale breaks down quickly when Knobs and Shale Belt View the KGS World Wide Web HillsSandstone, silt- and Berea are located in the Knobs Region. Streams that 275 471 exposed, leaving the limestone without support. site at www.uky.edu/kgs stone, shale, some coal flow through the Knobs and Shale Belt, such as the Villa Hills Silver Grove Ft. Mitchell Collapsed limestone rubble slips down the shale Pennyroyal Region Rolling Fork River (above) and Red River in the Burlington Erlanger Melbourne UplandsShale, sand- 275 Licking at this roadcut (below) on Ky. 53 in Washington east, carve wide valleys with fertile alluvium ° stone, siltstone, coal ° Florence 39 County. Cedar trees quickly reclaim a slope. The Eastern Kentucky Coal Field deposits. Marion County photo above. 39 Edgewood ALLUVIAL VALLEYS LowlandsLoess, river, BOONE Alexandria terrain of the Bluegrass Hills is characterized by Western Kentucky Coal Field and lake deposits: clay, Union Independence Ryland Inner BluegrassSinkholes are a common feature of the Inner Bluegrass rolling, knobby hills that provide pasture for live- Heights California terrain. Using sinkholes for waste disposal, even in rural areas, can stock, as seen in Grant County (left), and narrow silt, sand, and gravel 75 Visalia ridgetops than provide limited level land for crops Jackson Purchase Region threaten valuable water resources. While not a region as such, KENTON CAMPBELL and development. alluvial valleysdeposits Uplands Mentor 42 Walton R 27 84° Sinkholes of silt, sand, clay, and grav- 4 iv 14 el along large streams er BedrockThe 300-million-year-old shale, sandstone, siltstone, Bullock Pen Foster form an important land- Lake OHIO and coal that shape the region are exposed at this roadcut on Augusta State capital scape across Kentucky. 71 Butler the Natcher Parkway in Ohio County. Photo by Dave Williams, Dover From the wide Ohio River Warsaw Crittenden 9 Kentucky Geological Survey. PENDLETON County seat floodplain (left top, GALLATIN South Ghent Kincaid Maysville) that provides Boltz 25 Lake Brooksville OHIO Shore 16 Milton Glencoe Lake RIVE Incorporated city level land, water, and trans- Lowlands CARROLL Williamstown Falmouth R portation for communities Carrollton Sparta Dry Ridge Lake 10 Maysville + 16 10 and industry, to the narrow 421 BRACKEN 23 24 Parkway or Interstate highway Sanders 14 MASON Vanceburg valleys of eastern Kentucky TRIMBLE 55 K 127 36 e Williamstown th n GRANT N or Fork 9 Greenup Worthington (left bottom, Johnson t Worthville 17 2 Bedford u Creek Wurtland 41 U.S.