LOCATION CORNWALL MOEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, active, mesic Fragiaquic Paleudults
TYPICAL PEDON: Cornwall silt loam - on the summit of an intravalley ridge point with 3 percent slope in fescue pasture at an elevation of 625 feet. (Colors are for moist soil unless otherwise stated.)
Ap--0 to 5 inches; brown (10YR 4/3) silt loam; light gray (10YR 7/2) dry; weak fine granular structure; friable; many fine roots; neutral (pH 7.2); clear wavy boundary. (5 to 7 inches thick)
Bt--5 to 17 inches; yellowish brown (10YR 5/6) silty clay loam; weak fine and very fine subangular blocky structure; friable; common fine roots; common distinct clay films on faces of peds; strongly acid (pH 5.4); abrupt wavy boundary. (12 to 23 inches thick)
2Btx1--17 to 27 inches; yellowish brown (10YR 5/6) silt loam; weak very coarse prismatic structure parting to moderate medium platy and weak fine subangular blocky; firm; common fine roots in vertical pale brown seams; common medium and coarse prominent pale brown (10YR 6/3) clay depletions and common medium prominent yellowish red (5YR 5/6) masses of iron accumulation along seam exteriors; common fine black masses of iron and manganese accumulation; few distinct clay films on faces of peds; 2 percent chert gravel; 30 percent brittleness; very strongly acid (pH 5.0); clear smooth boundary.
2Btx2--27 to 39 inches; yellowish brown (10YR 5/6) silt loam; weak very coarse prismatic structure parting to moderate fine subangular blocky; firm; many medium and coarse prominent light brownish gray (10YR 6/2) iron depletions and common medium and coarse prominent yellowish red (5YR 4/6) masses of iron accumulation along seam exteriors; common very fine black masses of iron and manganese accumulation; few distinct clay films on faces of peds; 2 percent chert gravel; 40 percent brittleness; strongly acid (pH 5.2); gradual wavy boundary. (Combined thickness of the 2Btx horizon is 10 to 28 inches)
3Bt--39 to 60 inches; red (2.5YR 4/6) very gravelly silty clay loam; moderate fine and medium subangular blocky structure; very firm; few medium prominent brown (10YR 5/3) iron depletions and few fine prominent strong brown (7.5YR 5/8) masses of iron accumulation; common prominent clay films on ped faces; 42 percent chert gravel; strongly acid (pH 5.1).
TYPE LOCATION: Madison County, Missouri; about 2 miles north of Marquand; 3,500 feet south and 3,950 feet east of the northwest corner of sec. 17, T. 32 N., R. 8 E.; USGS Marquand quadrangle; latitude 37 degrees, 27 minutes, 21 seconds N., longitude 90 degrees, 11 minutes, 17 seconds W.
RANGE IN CHARACTERISTICS:
Depth to 2Btx: 17 to 35 inches
Depth to 3Bt: 39 to 59 inches
Depth to bedrock: More than 60 inches
A or Ap horizon
Hue: 10YR
Value: 3 to 5 (Note: where the value moist is 3, the value dry is 6)
Chroma: 3 or 4
Fine earth: silt loam
Rock fragments: 0 to 15 percent gravel
Reaction: strongly acid to very strongly acid, except where limed
E horizon (where present)
Hue: 10YR
Value: 4 to 6
Chroma: 3 or 4
Fine earth: silt loam
Rock fragments: 0 to 10 percent gravel
Reaction: strongly acid to very strongly acid
Bt horizon
Hue: 10YR or 7.5YR
Value: 4 to 6
Chroma: 4 to 6
Fine earth: silt loam, silty clay loam
Rock fragments: 0 to 10 percent gravel
Reaction: moderately acid to very strongly acid
2Btx horizon
Hue: 10YR to 2.5YR
Value: 4 or 5
Chroma: 4 to 6
Fine earth: silt loam, silty clay loam, clay loam
Rock fragments: 0 to 60 percent gravel, 0 to 10 percent cobbles
Reaction: strongly acid or very strongly acid
3Bt horizon
Hue: 10YR to 2.5YR
Value: 3 to 5
Chroma: 6 to 8
Fine earth: clay, silty clay loam, clay loam, silt loam
Rock fragments: 3 to 80 percent gravel and 0 to 15 percent cobbles
Reaction: strongly acid or very strongly acid
COMPETING SERIES: This is the Sowcoon series. Sowcoon soils are somewhat poorly drained.
GEOGRAPHIC SETTING: Cornwall soils are on high terraces, valley footslopes, intravalley ridge points, and in sinkholes. These soils formed in loess or silty sediments and loamy valley fill materials. Slopes range from 3 to 15 percent. The mean annual temperature is about 54 to 58 degrees F., and the mean annual precipitation is about 40 to 47 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Aslinger, Bearthicket, Britwater, Clarksville, Marquand, Roselle, and Tilk soils. Aslinger and Britwater soils are fine-loamy and are on lower terrace levels. Bearthicket soils are well drained and are on lower terrace levels. Clarksville soils are loamy-skeletal and are on adjacent side slopes. Roselle soils are fine-loamy and are at higher elevations. Marquand soils have a decrease in clay in the lower part of the control section, and are on similar landscape positions. Tilk soils are loamy-skeletal and are on flood plains. In addition, none of these soils except Aslinger have a brittle (2Btx) layer.
DRAINAGE AND PERMEABILITY: Moderately well drained. Runoff potential is low to medium. Permeability is moderately slow. The saturated hydraulic conducivity is moderately high. A perched high water table is present in most years at a depth of 2 to 3 feet.
USE AND VEGETATION: Most areas are planted to grasses and legumes and used for pasture and hay crops. The remaining acreage is mainly forested, with a small portion in small grain production. The native vegetation was mixed hardwoods and shortleaf pines.
DISTRIBUTION AND EXTENT: The Ozark Highland region (MLRA 116A) and the St. Francois Mountains region (MLRA 116C) of southeastern Missouri.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Morgantown, West Virginia
SERIES ESTABLISHED: Madison County, Missouri 1998.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
1) Ochric epipedon - the zone from the surface of the soil to a depth of 5 inches (Ap horizon);
2) argillic horizon - the zone from 5 to more than 60 inches (Bt, 2Btx1, 2Btx2, 3Bt horizons).
3) fragic feature - compaction and brittleness from 17 to 39 inches (2Btx1, 2Btx2 horizons)
ADDITIONAL DATA: Missouri University Soil Characterization Lab number M9012308.
These soils were previously mapped with Captina, Hildebrecht, and Weingarten soils.