LOCATION GUNLOCK MOEstablished Series
TAXONOMIC CLASS: Fine, mixed, active, mesic Fragic Oxyaquic Hapludalfs
TYPICAL PEDON: Gunlock silt loam - on a 6 percent slope in pasture at an elevation of 1,040 feet. (Colors are for moist soil unless otherwise stated.)
Ap--0 to 5 inches; dark grayish brown (10YR 4/2) silt loam, light brownish gray (10YR 6/2) dry; weak fine granular structure; friable; many fine and medium roots; moderately acid; clear smooth boundary. (4 to 9 inches thick)
Bt1--5 to 13 inches; yellowish brown (10YR 5/6) silty clay loam; common fine distinct strong brown (7.5YR 5/6) mottles; weak fine subangular blocky structure; firm; many fine and medium roots; few faint clay films; few fine dark masses of iron and manganese accumulation; moderately acid; clear smooth boundary.
Bt2--13 to 18 inches; yellowish brown (10YR 5/6) silty clay loam; common fine distinct strong brown (7.5YR 4/6) mottles; moderate fine subangular blocky structure; firm; common fine roots; common faint clay films; few medium dark masses of iron and manganese accumulation; moderately acid; clear smooth boundary.
Bt3--18 to 25 inches; brown (10YR 5/3) silty clay; common fine prominent strong brown (7.5YR 5/6) mottles; moderate fine subangular blocky structure; firm; common fine roots; common distinct clay films; 10 percent chert fragments; few medium dark masses of iron and manganese accumulation; slightly acid; gradual smooth boundary. (Combined thickness of the Bt horizon is 14 to 30 inches.)
2Btgx--25 to 32 inches; grayish brown (10YR 5/2) gravelly silty clay loam; weak coarse platy structure parting to weak fine subangular blocky; firm and very firm; compact and moderately expressed brittleness; few fine roots; few faint clay films; many medium prominent yellowish brown (10YR 5/8) and common fine prominent strong brown (7.5YR 4/6) masses of iron accumulation; 15 percent chert gravel; common medium dark masses of iron and manganese accumulation; moderately acid; clear smooth boundary.
2Btx--32 to 43 inches; yellowish brown (10YR 5/6) silty clay loam; weak coarse platy structure parting to weak fine subangular blocky; firm and very firm; compact and moderately expressed brittleness; few fine roots; few faint clay films; many medium prominent grayish brown (10YR 5/2) iron depletions; 10 percent chert gravel; common medium black masses of iron and manganese accumulation; moderately acid; gradual smooth boundary. (Combined thickness of the 2Btx horizons is 10 to 30 inches.)
3Bt1--43 to 55 inches; yellowish brown (10YR 5/6) extremely gravelly silty clay loam; moderate fine subangular blocky structure; firm; few distinct clay films; many medium prominent gray (10YR 6/1) iron depletions; 70 percent chert gravel; common medium black masses of iron and manganese accumulation; very strongly acid; gradual smooth boundary.
3Bt2--55 to 73 inches; yellowish brown (10YR 5/8) gravelly silty clay; weak fine subangular blocky structure; firm; common faint clay films; 30 percent chert gravel; few fine faint yellowish brown (10YR 5/6) masses of iron accumulation; common black masses of iron and manganese accumulation; very strongly acid.
TYPE LOCATION: Pulaski County, Missouri; 5 miles northeast of Richland; 1,015 feet north and 1,325 feet east of the southwest corner of sec. 23, T. 37 N., R. 13 W; Crocker, Missouri quadrangle, lat 37 degrees 55 minutes 10.4 seconds. N. and long. 92 degrees 19 minutes 47.6 seconds W.; NAD 83, UTM zone 15, UTM easting 558,898 and northing 4,107,101.
RANGE IN CHARACTERISTICS: Depth to bedrock is more than 60 inches but commonly less than 100 inches. Depth to horizons that have fragic characteristics ranges from 20 to 34 inches. Chert content by volume is less than 10 percent in the A and upper B horizons, 0 to 15 percent in the lower B above the 2Btx horizon and 5 to 50 percent in the 2Btx horizon, and 5 to 75 percent in the 3Bt horizon. The mean annual soil temperature at 20 inches is 55 to 59 degrees F.
The Ap or A horizon has value of 3 to 6, and chroma of 2 to 5. If the color value moist is less than 3.5, the A horizon is less than 6 inches thick. The E horizon, if present, has value of 5 or 6, and chroma of 3 to 6. They are strongly acid through neutral.
The Bt horizon has hue of 10YR or 7.5YR, value of 4 to 6, and chroma of 3 to 6. Mottles with value of 4 or more and chroma of 2 or less may be present at depths of more than 10 inches below the top of the Bt horizon. It is silt loam, silty clay loam, or silty clay. Reaction is very strongly acid to neutral.
The 2Btgx and 2Btx horizons have hue of 10YR to 5YR, value of 2 to 6, and chroma of 2 to 6. It is very strongly acid to neutral. Some pedons have 2E horizons. Expression of the brittleness is 30 to 60 percent of the matrix. It is silt loam, loam, or silty clay loam or their gravelly, very gravelly, or extremely gravelly analogues.
The 3Bt or 4Bt horizon has colors with hue of 10YR to 2.5YR, value of 3 to 6, and chroma of 2 to 8. It is silty clay loam, clay loam, silty clay or clay, or their gravelly to extremely gravelly analogues. It is very strongly acid to slightly alkaline.
Some pedons have neutral or mildly alkaline C horizons that have colors and textures similar to the 3Bt horizon.
COMPETING SERIES: There are no other series in this family.
GEOGRAPHIC SETTING: These gently to strongly sloping soils are on side slopes and foot slopes of the uplands and terraces. Slopes are commonly 2 to 9 percent, but range from 1 to 35 percent. The regolith consists of a thin mantle of loess and pedisediment over residuum weathered from interbedded sandstone and cherty dolomite. Mean annual temperature ranges from 54 to 57 degrees F, and mean annual precipitation ranges from 38 to 44 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Cedargap, Gatewood, Moniteau, Ocie and Union series. Cedargap and Moniteau soils have less clay and are on flood plains and low terraces below the Gunlock soils. Gatewood and Ocie soils are shallower to bedrock and are higher in elevation. Union soils have fragipans and are on rounded ridgetops and side slopes above the Gunlock soils.
DRAINAGE AND PERMEABILITY: Moderately well drained; high to very high runoff potential; slow permeability. The saturated hydraulic conductivity is moderately low. In undisturbed areas, the upper depth of a seasonal perched water table is 2.0 to 3.0 feet during December to March in most years.
USE AND VEGETATION: Most of the acreage is used for hay and pasture. Small grain crops are grown on some of the gentlest slopes. Oaks dominate the remaining acreage.
DISTRIBUTION AND EXTENT: The Ozark region (MLRAs 116A and 116B) of southern Missouri. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Morgantown, West Virginia
SERIES ESTABLISHED: Pulaski County, Missouri, 1984.
REMARKS: The classification was revised to include "Fragic" based on the latest edition of Soil Taxonomy.
Diagnostic horizons and features recognized in this series are:
1) ochric epipedon - the zone from the surface to a depth of 5 inches (Ap horizon),
2) argillic horizon - the zone from a depth of 5 to 73 inches (Bt1, Bt2, Bt3, 2Btgx, 2Btx, 3Bt1, and 3Bt2 horizons).
ADDITIONAL DATA: The University of Missouri soil characterization laboratory data reference number is M9316901.
The NASIS pedon site ID number is 00MO169009.