Physiographic Regions

Kentucky can be divided into three parts - the eastern mountains, the interior, and the Mississippi plains in the west. These large areas can be divided into several physiographic regions. The eastern end of the state is known as the Eastern Coal Field. The Appalachian Mountains extend into the state here and the highest point in Kentucky, Big Black Mountain, 4,145 feet above sea level, is here in Harlan county. The western end of this region is known as the Cumberland Plateau which extends west to the Pottsville Escarpment and the eastern Knobs, which divide eastern Kentucky from the rolling hills of the Bluegrass.

The eastern Kentucky coal field covers the eastern end of the state, stretching from the Appalachian Mountains westward across the Cumberland Plateau to the Pottsville Escarpment.

The Eastern Kentucky Coal Field is part of a larger physiographic region called the Cumberland Plateau (which extends from Pennsylvania to Alabama). The eastern edge of the Eastern Kentucky Coal Field (and Cumberland Plateau) is called the Pottsville or Cumberland Escarpment. This escarpment (in large part) is formed from resistant Pennsylvanian-age sandstones and conglomerates. The escarpment is stepped in south-central Kentucky because several thick, resistant sandstones are separated by less resistant shales. The manner in which the sandstones weather and are eroded along the escarpment results in sheer cliffs, steep-walled gorges, rockshelters, waterfalls, natural bridges and arches, caves, and some of the most scenic areas in Kentucky. Cumberland Falls State Resort Park, Red River Gorge and Natural Bridge State Resort Park are examples of some of these scenic areas along the escarpment.

Eastern Kentucky Climate

The climate of Kentucky is temperate with moderately cold winters and warm, humid summers. Temperature, rainfall, and humidity remain within limits agreeable to man and are suitable for varied plant and animal life. All seasons are marked by changes in weather that come from passing fronts and associated centers of high and low pressures. This activity is least in late spring and in summer, somewhat greater in fall, and greatest in winter and in early spring. Temperatures depart from the average least during the period of greatest activity. Temperatures at times will be lower-nearer the ground or in local areas subject to extreme air drainage. At times there may be considerable variation in temperature in hilly areas. Since the Forest is oriented north and south, the weather may vary considerably during a frontal passage.

Precipitation is fairly well distributed throughout the year; there are no wet or dry seasons. October has the least rainfall, July the most. Annual free-water evaporation from shallow lakes and farm-ponds averages about 35 inches, which is about 11 inches less than the average annual precipitation. About 74 percent of the evaporation occurs from May to October.

Snowfall is quite variable from year to year, and some winters have relatively little. The greatest annual total recorded for the period of this summary was 44.9 inches in 1960; the least recorded was 3.6 inches in 1949. Thunderstorms average about 46 days each year, most frequently in spring and summer but can occur in any month. They cause most of the short-duration, high intensity rainfall.

The growing season for plants that are killed by temperature of 32° F averages 166 days. The season is 187 days or more in 10 percent of the years, 177 days in 25 percent, 155 days or more in 75 percent, and 145 days or more in 90 percent.