Most of this area is in the Till Plains Section of the Central Lowland Province of the Interior Plains.
The western part of the area in Missouri is in the Dissected Till Plains Section of the same province and division.
The southern edge is in the Springfield-Salem Plateaus Section of the Ozark Plateaus Section of the Ozark Plateaus Province of the Interior Highlands.
73% of this area within Illinois.
21% of this area within Missouri.
6% of this area within Iowa.
Total Land Area 13,650 square miles (35,375 square kilometers).
Muscatine, Burlington, and Fort Madison, Iowa.
Peoria, Canton, Macomb, and Quincy, Illinois.
This area also includes the Quad Cities of of Moline and Rock Island, Illinois, and Bettendorf and Davenport, Iowa, in the northwest tip of this area.
The area has a number of State parks and national wildlife refuges, especially along the Mississippi River. Small parcels of State forests are in the part of the MLRA in Illinois.
The glacial drift and loess deposits are underlain by several bedrock systems. The Cretaceous System is of minor extent, occurring only in Pike and Adams Counties, Illinois. The Pennsylvanian System occurs in the eastern part. The Mississippian System occurs along the Mississippi and Illinois Rivers. The Silurian System occurs in the northern and southern parts of the area. The Devonian System occurs only in the northern part of the area, and the Ordovician System occurs only in the southern part. Bedrock outcrops are common on the bluffs along the Mississippi River.
The uplands in this area are covered almost entirely with Wisconsin loess. The loess is thick on stable summits. The loess is underlain dominantly by glacial drift consisting of distinct till units. Illinoian glacial drift is the dominant drift in Illinois and is of minor extent in Iowa. Pre-Illinoian drift is in the parts in Iowa and Missouri and to a minor extent in the western part of Illinois, in Hancock, Adams, and Pike Counties. Wisconsin outwash deposits and sandy eolian material are on some of the stream terraces along the major tributaries.
Unglaciated areas are in the southwestern portion of the part of the area in Illinois.Topography -
Elevation ranges from 420 to 885 feet (130 to 270 meters). Relief is typically 10-20 feet (3 - 6 meters).
Relief can be 50 to 100 feet (15 to 30 meters) along drainageways and streams. Also, the bluffs along the Illinois and Mississippi Rivers are as much as 250 feet (75 meters) above the valley floors.
The average annual precipitation in this area is 34 to 40 inches (865 to 1,015 millimeters).
Most of the rainfall occurs as high-intensity, convective thunderstorms.
The average annual temperature is 48 to 55 degrees F (9 to 13 degrees C).
The freeze-free period averages about 200 days and ranges from 180 to 215 days.
* this is the percent of area drained by each named hydrologic unit
The Mississippi River flows through this area, forming the boundaries between Iowa and Illinois and between Missouri and Illinois.
|Public supply||surface water||3.8%||ground water||0.6%|
|Livestock||surface water||0.1%||ground water||0.1%|
|Irrigation||surface water||0.1%||ground water||1.1%|
|Other||surface water||92.9%||ground water||1.4%|
Total daily withdrawls average 3,555 million gallons per day 13.455 million liters).
3% Ground water sources
97% Surface water sources
Most of the large rivers in the area carry heavy sediment loads and have low-quality water. The waterflow is regulated by dams in the upper reaches of most rivers.
Water quality is a concern in karst areas and in urban areas. Also, it is degraded by agricultural runoff.
Abundant ground water occurs in deposits of unconsolidated sand and gravel along the large rivers throughout this area.The average values of total dissolved solids are close to 500 parts per million (milligrams per liter),
Away from the river valley deposits in Illinois, ground water can be obtained from the Pennsylvanian-Mississippian and Shallow Dolomite aquifers. The water from these aquifers is similar in quality to the water in the river valleys.
Areas away from the river valley deposits in Missouri have two sources of ground water. A glacial drift aquifer lies over the Pennsylvanian-Mississippian aquifer in these areas. The water quality varies considerably. The level of total dissolved solids can be 500 to 3,000 parts per million (milligrams per liter).
In Karst topography in the southern end of this area, contaminated water from surface activities has created some local water-quality problems in the Pennsylvanian-Mississippian aquifer.
The Jordan aquifer is the most extensively used aquifer in Iowa. It consists of sandstone and dolomite of Ordovician and Cambrian age. The median level of total dissolved solids typically exceeds 800 parts per million (milligrams per liter), and radium-226 levels can exceed the national standard for drinking water.
The Silurian-Devonian aquifer consists of limestone and dolomite. It is close to the surface in Iowa, and it has the best water quality of all the principal aquifers in Iowa. Where this aquifer is buried by younger bedrock deposits, the level of total dissolved solids and naturally high levels of sulfate limit use of the water.
The soils are shallow to very deep, poorly drained to excessively drained and loamy, silty, or clayey.
|Endoaquolls||Sable, Virden series||formed in loess on broad upland summits and flats.|
|Albaqualfs||Rushville, Denny series||formed in loess on broad upland summits and flats.|
|Argiudolls||Ipava, Osco, Tama series||formed in loess on broad upland summits and flats or uplands.|
|Endoaqualfs||Keomah series||formed in loess on broad upland summits and flats.|
|Endoaquolls||Beaucoup, Otter, and Sawmill series||formed in alluvium on nearly level, broad flood plains.|
|Hapludalfs||Fayette, Rozetta, Seaton, Winfield, Menfro series||formed in thick deposits of loess on uplands.|
|Hapludolls||Huntsville, Ross, Tice series||formed in alluvium on nearly level, broad flood plains.|
There are many other soil series listed in the USDA information.
Oak, hickory, and sugar maple are the dominant species. Big bluestem, little bluestem, and scattered oak and eastern redcedar trees grow on some upland sites.
The lowlands support mixed forest vegetation, mainly elm, cottonwood, river birch, ash, silver maple, and willow. Sedge and grass meadows and scattered trees are on some lowlands.
Some of the major wildlife species include whitetailed deer, gray and red fox, beaver, mink, raccoon, opossum, great horned owl, bobwhite quail, and wood duck.
|59% -||Cropland||- private|
|11% -||Grassland||- private|
|17% -||Forest||- private|
|1% -||- Federal|
|6% -||Urban development||- private|
|4% -||Water||- private|
|2% -||Other||- private|
Corn, soybeans, and other feed grains are the principal crops. Specialty crops include watermelons, pumpkins and orchards.
The major resource concerns include wind and water erosion, flooding, wetness; maintenance of the content of organic matter in the soils and productivity of the soils.
Conservation practices on cropland generally include crop residue management (no till), cover crops, windbreaks, vegetative wind barriers and nutrient and pest management. Woodland management practices, such as exclusion of grazing and timber stand improvement, are important for timber production.