LOCATION GRAVOIS MOEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, active, mesic Aquic Paleudalfs
TYPICAL PEDON: Gravois silt loam on a ridgetop of 5 percent slope in second growth forest land at an elevation of 860 feet. (Colors are for moist soil unless otherwise stated.)
Ap--0 to 6 inches; dark grayish brown (10YR 4/2) silt loam; light brownish gray (10YR 6/2) dry; weak fine granular structure; friable; many very fine and medium roots; strongly acid (pH 5.2); clear smooth boundary. (3 to 7 inches thick)
Bt1--6 to 12 inches; yellowish brown (10YR 5/6) silt loam; weak fine subangular blocky structure; firm; many fine and medium roots; common distinct dark yellowish brown (10YR 4/4) clay films on faces of peds; common prominent pale brown (10YR 6/3) clay depletions on faces of peds; strongly acid (pH 5.2); clear smooth boundary.
Bt2--12 to 18 inches; yellowish brown (10YR 5/6) silty clay loam; moderate fine subangular blocky structure; firm; common fine roots; few distinct brown (10YR 4/3) clay films on faces of peds; common distinct pale brown (10YR 6/3) clay depletions on faces of peds; strongly acid (pH 5.2); clear smooth boundary.
Bt3-- 18 to 25 inches; yellowish brown (10YR 5/6) silty clay loam; moderate fine subangular blocky structure; firm; common fine roots; few distinct brown (10YR 4/3) clay films on faces of peds; common distinct strong brown (7.5YR 5/6) masses of iron-manganese; strongly acid (pH 5.2); clear smooth boundary. (Combined thickness of the Bt horizon is 10 to 30 inches.)
2Btx--25 to 35 inches; yellowish brown (10YR 5/6) silty clay loam; weak medium and coarse prismatic structure parting to weak fine and medium subangular blocky; very firm; 40 percent brittle; common very fine roots between peds; few dark grayish brown (10YR 4/2) clay films on vertical faces of peds, in root channels, and in pores; common prominent black (10YR 2/1) iron-manganese stains; many distinct grayish brown (10YR 5/2) iron depletions; common prominent yellowish red (5YR 4/6) masses of iron accumulation; 5 percent chert gravel; strongly acid (pH 5.3); gradual smooth boundary. (8 to 35 inches thick)
3Bt1--35 to 50 inches; yellowish brown (10YR 5/6) very gravelly silty clay loam; moderate medium subangular blocky structure; firm; few fine roots; few distinct dark grayish brown (10YR 4/2) clay films on faces of peds; few prominent black (10YR 2/1)iron-manganese stains; many distinct grayish brown (10YR 5/2) iron depletions; common prominent yellowish red (5YR 4/6) masses of iron accumulation; 40 percent chert gravel and 10 percent chert cobbles; strongly acid (pH 5.3); gradual smooth boundary. (0 to 20 inches thick)
4Bt2--50 to 80 inches; red (2.5YR 4/6) very cobbly clay; moderate medium subangular blocky structure; firm; common prominent brown (7.5YR 4/3) clay clay films on faces of peds; few prominent black (10YR 2/1) iron-manganese stains; common yellowish red (5YR 4/6) masses of iron accumulation; 30 percent chert gravel and 20 percent chert cobbles; slightly alkaline (pH 7.5)
TYPE LOCATION: Miller County, Missouri; 1,000 feet west and 900 feet south of the northeast corner of section 22, T. 39N, R. 15W.; UTM Zone: 15, UTM Easting 539,049, UTM Northing 4,217,801; NAD 83; latitude 38 degrees, 6 minutes, 25.9 seconds, longitude 92 degrees, 33 minutes, 16.5 seconds.
RANGE IN CHARACTERISTICS:
Depth to the 2Btx horizon is 18 to 40 inches. The depth to the top of a subhorizon with more than 15 percent rock fragments is less than 40 inches. Depth to bedrock is more than 60 inches. The mean annual soil temperature at 20 inches is 55 to 59 degrees F.
A or Ap horizon
Hue: 10YR
Value: 3 or 4
Chroma: 2 or 3
Fine earth: silt loam
Rock fragments: 0 to 10 percent gravel
Reaction: extremely acid to neutral
E or EB horizon (where present)
Hue: 10YR
Value: 4 to 6
Chroma: 2 to 4
Fine earth: silt loam
Rock fragments: 0 to 10 percent gravel
Reaction: moderately to very strongly acid
Bt
Hue: 7.5YR or 10YR
Value: 4 to 6
Chroma: 3 to 8, can be 2 in lower part
Fine earth: silt loam or silty clay loam
Rock fragments: 0 to 10 percent gravel, 0 to 5 percent
cobbles
Reaction: neutral to very strongly acid
Btx, 2Btx, and 3Btx
Hue: 5YR to 10YR
Value: 4 to 6
Chroma: 1 to 8
Fine earth: loam, silt loam, or silty clay loam
Rock fragments: 5 to 65 gravel, 0 to 20 percent
cobbles
Reaction: extremely acid to neutral
3Bt
Hue: 10R to 10YR
Value: 2 to 6
Chroma: 2 to 8
Fine earth: loam, silt loam, or silty clay loam,
Rock fragments: 15 to 80 gravel, 0 to 20 percent
cobbles, 0 to 20 percent stones
Reaction: very strongly acid to slightly
alkaline
4Bt
Hue: 10R to 10YR
Value: 3 to 6
Chroma: 2 to 8
Fine earth: silty clay, or clay
Rock fragments: 5 to 80 gravel, 0 to 25 percent
cobbles, and 0 to 20 percent stones
Reaction: extremely acid to slightly alkaline
COMPETING SERIES: There are no other series in this family. Soils in similar families are the Rend and Wrengart soils. Rend soils have less than 15 percent rock fragments in the lower part of the series control section. Wrengart soils are more than 40 inches to subhorizons with more than 15 percent rock fragments.
GEOGRAPHIC SETTING: The Gravois soils are on convex ridgetops and sideslopes. Slopes range from 3 to 35 percent. These soils formed in a thin mantle of loess and pedisediment, and the underlying loamy and clayey residuum from dolomite. The contact of the contrasting material is marked by a gravelly erosional surface. Mean annual temperature ranges from 54 to 57 degrees F. and the mean annual precipitation ranges from 36 to 42 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Bardley, Clarksville, Gatewood, Goss, Lebanon, Niangua, and Useful series. Bardley and Gatewood soils have bedrock at less than 40 inches and are on adjacent side slopes. Clarksville and Goss soils are gravelly throughout and are on narrower ridgetops and adjacent side slopes. Lebanon soils have a fragipan and are on similar landscapes. Niangua soils have a gravelly surface layer, bedrock at 40 to 60 inches, and are on adjacent side slopes. Useful soils have bedrock at 40 to 60 inches and are on similar landforms.
DRAINAGE AND PERMEABILITY: Moderately well drained. Permeability is moderate in the Bt horizon and slow in the 2Btx horizon. The saturated hydrolic conductivity is low. The surface runoff index is high to very high. A perched water table is present at 1.5 to 3.0 feet from winter to early spring in most years.
USE AND VEGETATION: Most areas of these soils are cleared and used for grass and legume pasture or hay crops. The remainder is in forest. Native vegetation was mixed hardwoods.
DISTRIBUTION AND EXTENT: The Ozark area (MLRAs 116A and 116B) of Missouri. This series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Morgantown, West Virginia
SERIES ESTABLISHED: Maries County, Missouri, 1999.
REMARKS: Diagnostic horizons and features recognized in this series are:
Ochric epipedon - the zone from the surface of the soil to a depth of 6 inches (Ap horizon)
Argillic horizon - the zone from 6 to 80 inches (Bt1, Bt2, Bt3, 2Btx, 3Bt1, and 4Bt2 horizons)
Fragic layer - the zone from 25 to 35 inches (2Btx horizon)
ADDITIONAL DATA: Missouri University soil characterization laboratory number M9713139. The NASIS pedon site ID is 97MO131074.