The Bluegrass Region
Dark green - Eastern Kentucky Coal fields (Cumberland Plateau)
Green - Outer Bluegrass
Light Green - Inner Bluegrass
Light Brown - Mississippi (Pennyroyal) Plateau
Brown - Western Kentucky Coal Field
Dark Brown - Jackson Purchase
The Bluegrass region is characterized by underlying fossiliferous limestone, dolostone, and shale of the Ordovician geological age. Hills are generally rolling, and the soil is highly fertile for growing pasture. Because of this, the Bluegrass is well known for its horse farms. However, the area is becoming increasingly developed with residential and commercial properties, particularly around Lexington. Farms are losing ground to this development and are slowly disappearing. This has led the World Monuments Fund to include the Bluegrass region on its global list of 100 most endangered sites.
The Kentucky Bluegrass is bounded on the east by the Cumberland Plateau, with the Pottsville Escarpment forming the boundary. On the south and west, it borders the Pennyroyal Plateau, (also called the Pennyrile), with Muldraugh Hill, another escarpment, forming the boundary. Much of the region is drained by the Kentucky River and its tributaries. The river cuts a deep canyon through the region, preserving meanders that indicate that the river was once a mature low valley that was suddenly uplifted. Particularly near the Kentucky River, the region exhibits karst topography, with sinkholes, caves, and disappearing streams which drain underground to the river.
(Adapted from Bluegrass Region at Wikipedia)