Till Plains Section of the Central Lowland Province of the Interior Plains of Illinois area.
The part in Missouri is in the Dissected Till Plains Section of the same province and division.
69% of this are within Illinois.
31% of this area within Missouri.
Total Land Area 12,790 square miles (33,150 square kilometers).
Carbondale, Centralia, Effingham, Herrin, Marion and Mount Vernon, Illinois.
Mexico and Moberly, Missouri
Parts of the Shawnee National Forest, Crab Orchard National Wildlife Refuge are within this MLRA.
Pennsylvanian limestone and shale bedrock underlies the glacial till in both Missouri and Illinois.
It is an area of gently sloping to rolling, dissected plains. The northern part of the area has a thin mantle of loess.
Loess overlies old (pre-Wisconsin) glacial drift that has a high content of clay in this MLRA. This area consists of nearly level to gently sloping, old till plains. Stream valleys are shallow and generally are narrow.Topography -
Elevation is 660 to 980 feet (200 to 300 meters) in Missouri and about 660 feet (200 meters) in Illinois, increasing gradually from south to north in both States. Local relief is generally 5 to 10 feet (1.5 to 3 meters).
The average annual precipitation in this area is 36 to 46 inches (915 to 1,170 millimeters).
Most of the rainfall occurs as convective thunderstorms during the growing season.
The average annual temperature is 51 to 57 degrees F (11 to 14 degrees C).
The freeze-free period averages about 205 days and ranges from 190 to 225 days.
* this is the percent of area drained by each named hydrologic unit
The Kaskaskia, Little Muddy, Little Wabash, Embarras, and Saline Rivers are in the part of this area in Illinois.
Mark Twain Lake, a major reservoir on the Salt River, and the North and West Forks of the Cuivre River are in the part of the area in Missouri.
|Public supply||surface water||26.5%||ground water||4.1%|
|Livestock||surface water||0.2%||ground water||0.2%|
|Irrigation||surface water||0%||ground water||2.1%|
|Other||surface water||62.5%||ground water||4.3%|
Total daily withdrawls average 450 million gallons per day (1.705 million liters).
11% Ground water sources
89% Surface water sources
Reservoirs have been built on the larger rivers in this area to provide drinking water and water for industries and is generally of good quality.
Small to moderate quantities of ground water are available in this area. The supply of ground water from glacial drift in Missouri is small, undependable, and of poor quality (because of high concentrations of naturally occurring salts). Wells in the Pennsylvanian-Mississippian sediments in the part of this area in Illinois produce low yields. Little is known about the quality of the water in this aquifer.
The soils are very deep, loamy or clayey, and can range from well drained to poorly drained.
|Hapludalfs||Armstrong, Hoyleton, and Keswick series||formed in loess and/or pedisediment over till on uplands|
|Hapludalfs||Hickory series||formed in till on till plains|
|Fragiudalfs||Ava series||formed in loess and/or pedisediment over till on uplands|
|Epiaqualfs||Bluford and Mexico series||formed in loess over pedisediment|
|Epiaqualfs||Leonard series||formed in loess over till on uplands.|
|Albaqualfs||Putnam series||formed in loess|
|Albaqualfs||Cisne series||loess over pedisediment|
|Albaqualfs||Wynoose series||loess and/or pedisediment over till on uplands.|
When this area was settled, most of the level soils on uplands supported tall prairie grasses, mainly big bluestem, Indiangrass, prairie dropseed, and switchgrass. The present potential for natural vegetation on these soils is unknown.
Forests of post oak, swamp white oak, blackjack oak, and pin oak grow on poorly drained soils. White oak, shingle oak, black oak, hickory, white ash, basswood, sugar maple, elm, and walnut grow on the better drained soils. Silver maple, willows, cottonwood, sycamore, elm, pin oak, white oak, hickory, and ash grow on flood plains.
Some of the major wildlife species include whitetailed deer, coyote, turkey, and bobwhite quail.
|67% -||Cropland||- private|
|10% -||Grassland||- private|
|1% -||- Federal|
|13% -||Forest||- private|
|5% -||Urban development||- private|
|2% -||Water||- private|
|2% -||Other||- private|
Corn, soybeans, other feed grains, and hay are the principal crops. Some cotton is grown in Oklahoma. More than 2/5ths of the area supports pasture grasses and legumes. The grassland in the area supports introduced and native grasses. The forested areas are mainly on the steeper slopes and on wet bottom land.
The major resource concerns include wetness, water erosion, flooding, limited available water capacity and maintenance of the content of organic matter in the soils and productivity of the soils, particulary those with high sodium content.
Conservation practices on cropland generally include surface and subsurface drainage systems, crop residue management, filter strips, cover crops, and nutrient and pest management.