LOCATION NIANGUA MOEstablished Series
TAXONOMIC CLASS: Very-fine, mixed, active, mesic Typic Hapludalfs
TYPICAL PEDON: Niangua very gravelly silt loam, stony - on a north-facing 25 percent slope in woodland at an elevation of 850 feet. (Colors are for moist soil unless otherwise stated.)
A--0 to 3 inches; black (10YR 2/1) very gravelly silt loam; dark gray (10YR 4/1) dry; weak fine granular structure; very friable; many fine roots; 40 percent chert gravel; stone sized fragments cover about 3 percent of the soil surface; neutral; abrupt smooth boundary. (2 to 7 inches thick)
E--3 to 14 inches; pale brown (10YR 6/3) very gravelly silt loam; weak fine granular structure; very friable; many fine and medium roots; 60 percent chert gravel; moderately acid; clear smooth boundary. (4 to 16 inches thick)
2Bt1--14 to 25 inches; red (2.5YR 4/6) gravelly clay; moderate fine subangular blocky structure; firm; common fine and medium roots; few faint clay films on faces of peds; many fine prominent yellowish red (5YR 5/6) and common fine faint dark red (2.5YR 3/6) masses of iron accumulation; 25 percent chert fragments; strongly acid; clear smooth boundary.
2Bt2--25 to 46 inches; red (2.5YR 4/6) clay; moderate fine subangular blocky structure; firm; few medium roots; common faint clay films on faces of peds; many fine prominent brown (7.5YR 5/4) and common fine prominent brown (10YR 5/3) masses of iron accumulation; 10 percent chert gravel; moderately acid; gradual smooth boundary.
2Bt3--46 to 52 inches; yellowish brown (10YR 5/4) gravelly clay; moderate fine subangular blocky structure; common faint clay films on faces of peds; many fine prominent strong brown (7.5YR 4/6) and common fine prominent yellowish red (5YR 5/6) masses of iron accumulation; 25 percent chert gravel; slightly alkaline; abrupt wavy boundary.
2R--52 inches; chert bed 3 inches thick overlaying hard dolostone.
TYPE LOCATION: Camden County, Missouri; about 4 miles southeast of Camdenton, 1625 feet north and 1050 feet west of the southeast corner, section 16, T. 37, R. 17 W; Hahatonka quadrangle, 37 degrees 56 minutes 37 seconds N. and long. 90 degrees 47 minutes 57 seconds W..
RANGE IN CHARACTERISTICS: Depth to bedrock ranges from 40 to 60 inches. The particle-size control section averages over 60 percent clay.
The A horizon has hue of 10YR, value of 2 to 4, and chroma of 1 to 4. It is silt loam, gravelly silt loam, or very gravelly silt loam. Reaction is neutral to very strongly acid.
The E horizon and BE horizons, if present, have hue of 10YR, value of 5 or 6 and chroma of 2 to 4. Texture is the gravelly to extremely gravelly analogues of silt loam or silty clay loam. Reaction is moderately acid to vert strongly acid.
The upper 2Bt horizon has hue of 2.5YR to 7.5YR, value of 3 to 5, and chroma of 4 to 8. Texture is silty clay or clay or their gravelly analogues. Reaction ranges from moderately acid to very strongly acid. The middle part of the 2Bt horizon has matrix colors in hue of 2.5YR or 5YR, value of 4 or 5, and chroma of 4 to 8. Mottles have hue of 2.5YR to 10YR, value of 3 to 6 and chroma of 3 to 8. Texture is clay or gravelly clay. Reaction is moderately or strongly acid.
The lower 2Bt horizon has hue of 10R to 10YR, value of 4 or 5 and chroma of 3 to 8. Texture is clay or gravelly clay. Reaction ranges from moderately acid to mildly alkaline. Chert content in the 2Bt ranges from 0 to about 25 percent. In some pedons this horizon rests on bedded chert 3 to 10 inches thick over dolomite bedrock. In others, it directly overlies the weathered surface of hard dolostone. Some pedons have a sandy clay or sandy clay loam 3Bt horizon with the same colors as the 2Bt.
COMPETING SERIES: These are the Bardley, Carbo, Chilhowie, Endcav, and Oshkosh series. Bardley, Carbo, and Chilhowie soils have bedrock at 20 to 40 inches. Endcav soils have cooler temperatures and more rainfall in July and August, lower Thornwaite PE indices and have fewer coarse fragments in the surface layer. Oshkosh soils have thinner sola and do not have bedrock within a depth of 60 inches.
GEOGRAPHIC SETTING: These soils are on strongly sloping to very steep side slopes and footslopes. Slope gradients are dominantly 14 to 40 percent but range from 9 to 50 percent. These soils formed in cherty sediments and residuum from cherty dolomite. Average annual temperature ranges from 54 to 57 degrees F, and average annual precipitation ranges from 38 to 48 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Bardley, Doniphan, Gasconade, Gepp, Goss, and Union soils. Bardley soils are moderately deep and are on similar positions. Doniphan, Gepp, and Goss soils are deeper to bedrock and higher in elevation. Doniphan soils are on narrow ridge positions and Gepp and Goss are on side positions. Gasconade soils are shallow and typically on south facing aspects. Union soils have fragipans and are on ridge summit positions.
DRAINAGE AND PERMEABILITY: Well drained. Runoff potential is high to very high. Permeability is moderately slow.
USE AND VEGETATION: Most areas are in oak-hickory forest. Some less sloping areas have been cleared and are used for pasture. Native vegetation is mixed hardwoods.
DISTRIBUTION AND EXTENT: Missouri Ozark region and possibly Arkansas. The soil is estimated to be moderate in extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Morgantown, West Virginia
SERIES ESTABLISHED: Camden County, Missouri, 1988.
REMARKS: Diagnostic horizons and features recognized in this series are:
ochric epipedon - the zone from the surface of the soil to a depth of 14 inches (A, E horizons);
argillic horizon - the zone from approximately 14 to 52 inches (2Bt1, 2Bt2, 2Bt3 horizons);
udic moisture regime;
lithic contact - 52 inches (R horizon)