LOCATION ROCKBRIDGE WIEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, mesic Typic Hapludalfs
TYPICAL PEDON: Rockbridge silt loam, on a convex, east-facing slope of 15 percent, in a cultivated field, at an elevation of 990 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 very fine subangular blocky structure; friable; many fine roots; neutral; abrupt wavy boundary. (5 to 9 inches thick)
E--6 to 8 inches; grayish brown (10YR 5/2) silt loam, light brownish gray (10YR 6/2) dry; moderate thin platy structure; friable; many fine roots; thin coats of clean silt on surfaces of peds; neutral; clear wavy boundary. (0 to 4 inches thick)
Bt1--8 to 13 inches; brown (10YR 4/3) silt loam; weak fine subangular blocky structure; friable; common fine roots; few distinct brown (7.5YR 4/3) clay films on faces of peds and few thin coats of clean silt on surfaces of peds near the upper boundary; fine wormholes and root casts; moderately acid; clear wavy boundary. (3 to 5 inches thick)
Bt2--13 to 20 inches; brown (10YR 4/3) silty clay loam; moderate medium subangular blocky structure; friable; common fine roots; few distinct brown (7.5YR 4/3) clay films on surfaces of peds; thin coats of silt skeletans along faces of primary vertical cleavage planes; few (less than 5 percent) chert pebbles; moderately acid; clear wavy boundary. (5 to 7 inches thick)
2Bt3--20 to 25 inches; brown (7.5YR 4/4) gravelly silty clay loam; strong medium subangular blocky structure; firm; common fine roots; many faint brown (7.5YR 4/3) clay films on faces of peds; thin patchy coats of silt skeletans on surfaces of peds; 30 percent by volume of chert pebbles and cobblestones; strongly acid; clear wavy boundary.
2Bt4--25 to 35 inches; brown (7.5YR 4/4) very gravelly silty clay loam; moderate medium subangular blocky structure; firm; few fine roots; many faint brown (7.5YR 4/3) clay films on surfaces of peds; 50 to 60 percent by volume of chert pebbles with some cobblestones to 10 inches in diameter; strongly acid; clear wavy boundary. (Combined thickness of the 2Bt horizon ranges from 5 to 30 inches.)
2BC--35 to 62 inches; brown (7.5YR 4/4) very gravelly sandy loam; massive; firm; few fine roots; 50 to 60 percent chert pebbles with some cobblestones to 10 inches in diameter; very strongly acid. (0 to 30 inches thick)
3C--62 to 70 inches; 50 percent brownish yellow (10YR 6/6) and 50 percent dark greenish gray (5GY 4/1) fine sandy loam; moderate coarse subangular blocky structure; friable; common very fine and fine roots; very few prominent yellowish brown (10YR 5/4) clay films on faces of peds; 10 percent channers; strongly acid; abrupt wavy boundary.
3Cr--70 to 80 inches; 20 percent dark greenish gray (5G 4/1) and 80 percent brownish yellow (10YR 6/6) weakly cemented fine-grained glauconitic sandstone; strongly acid.
TYPE LOCATION: Vernon County, Wisconsin; about 4 miles north of Hillsboro; located about 1,000 feet west and 1,300 feet north of the southeast corner of section 2, T. 14 N., R. 1 E.; USGS Hillsboro topographic quadrangle; lat. 43 degrees 43 minutes 00 seconds N. and long. 90 degrees 20 minutes 10 seconds W., NAD 83.
RANGE IN CHARACTERISTICS:
Depth to paralithic contact with glauconitic sandstone--60 to 80 inches
Thickness of loess--10 to 25 inches thick
Kind of rock fragments--chert and dolostone in the lower part of the loess and pedisediment and glauconitic sandstone in the loamy residuum
Volume of gravel--0 to 15 percent in the lower part of the loess, 15 to 75 percent in the pedisediment
Volume of cobbles--0 to 15 percent in the pedisediment
Volume of channers in loamy residuum--0 to 35 percent
Ap horizon:
Hue--10YR
Value--3 to 5
Chroma--2 or 3
Texture--silt loam
Content of clay--14 to 22 percent
Reaction--strongly acid to slightly acid but ranges to neutral, where limed
A horizon, where present:
Hue--10YR
Value--2 or 3
Chroma--1 or 2
Texture--silt loam
Content of clay--14 to 22 percent
Reaction--strongly acid to slightly acid
E horizon:
Hue--10YR
Value--4 to 6
Chroma--2 or 3
Texture--silt loam
Content of clay--14 to 22 percent
Reaction--strongly acid to slightly acid but ranges to neutral, where limed
Bt horizon:
Hue--7.5YR or 10YR
Value--4 to 6
Chroma--3 or 4
Texture--silt loam or silty clay loam
Content of clay--18 to 35 percent
Reaction--strongly acid to slightly acid but ranges to neutral, where limed
2Bt horizon:
Hue--2.5YR, 5YR, or 7.5YR
Value--4 or 5
Chroma--3 to 6
Texture--gravelly or very gravelly analogs of loam, silty clay loam, sandy clay loam, clay loam or clay
Content of clay--20 to 45 percent
Reaction--very strongly acid to slightly acid
2BC horizon:
Hue--5YR, 7.5YR, or 10YR
Value--4 or 5
Chroma--4 to 8
Texture--very gravelly or extremely gravelly analogs of sandy loam or loam
Content of clay--10 to 20 percent
Reaction--very strongly acid to slightly acid
3C horizon, where present:
Hue--10YR, 2.5Y, 5Y, 5GY, 10GY, or 5G
Value-3 to 8
Chroma--1 to 6
Texture--fine sandy loam, sandy loam, loam, sandy clay loam or the channery analogs
Content of clay--10 to 26 percent
Reaction--very strongly acid to moderately acid
3Cr horizon:
Color is similar to the 3C or 3Bt horizon
COMPETING SERIES: These are the Bluemount(T), Caprell, Coggon, Douds, Grellton, Kendallville, Kliever(T), Letort, Lindley, Mchenry, Norden, Pecatonica, Plumcreek, Renova, Westville, and Whalan series. Bluemount(T)soils have a lithic contact at 20 to 40 inches. Caprell, Coggon, Douds, Grellton, Kendallville, Kliever(T), Letort, Lindley, Mchenry, Pecatonica, Plumcreek, Renova, Westville, and Whalan soils do not have 35 to 70 percent rock fragments in the lower part of the series control section. The Norden soils have a paralithic contact with bedrock at 20 to 40 inches.
GEOGRAPHIC SETTING:
Parent material--loess, pedisediment, and loamy residuum from underlying fine-grained glauconitic sandstone
Landform--Hills in bedrock controlled uplands
Geologic Formation--Typically the Tunnel City sandstone that is identified, in part by a high content of glauconitic sandstone
Slope--6 to 20 percent
Elevation--750 to 1,000 feet
Mean Annual Air Temperature--48 to 52 degrees F
Mean Annual Precipitation--30 to 34 inches
Frost-Free Period--135 to 165 days
GEOGRAPHICALLY ASSOCIATED SOILS:
These are the
Council and
Norden soils near the Type Location. The Council soils are lower on the landscape positions. The Norden soils are higher on the landscape positions. The Council soils are coarse-loamy. The Norden soils have a paralithic contact with bedrock within depths of 40 inches.
DRAINAGE AND PERMEABILITY:
Drainage class--Well drained
Permeability--Moderate in the loess, slow to moderate in the pedisediment, moderate or moderately rapid in the loamy residuum, and slow to moderate in the sandstone
Runoff--Medium
USE AND VEGETATION: Most areas are used for cropland. Common crops are corn, small grain, and hay. Steeper areas are in woodland or pastureland. Native vegetation is mixed hardwoods, mostly oaks.
DISTRIBUTION AND EXTENT: Southwestern Wisconsin. MLRA 105. This series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: St. Paul, Minnesota.
SERIES ESTABLISHED: Richland County, Wisconsin, 1947. Source of the name is a village in Richland County.
REMARKS:
Diagnostic horizons and features recognized in this pedon include:
Ochric epipedon--the zone from 0 to 6 inches;
Albic horizon--the zone from 6 to 8 inches;
Argillic horizon--the zone from 8 to 35 inches;
Paralithic contact--the contact with glauconitic sandstone at 70 inches.
The Rockbridge series was classified as Gray Brown Podzolic soils in recently published soil surveys.
Type Location was visited on November 11, 2001 to verify and add residuum and glauconitic sandstone in the lower part of the profile.