LOCATION CORNHILL VI+PR
Inactive Series
Rev. BCD
05/2017
CORNHILL SERIES
The Cornhill series consists of very deep, moderately well drained, slowly permeable upland soils. They formed in loamy materials over clayey marine sediments. Slopes range from 0 to 2 percent. The mean annual precipitation is about 35 inches and the mean annual temperature is about 79 degrees F.
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, isohyperthermic Fluventic Haplustepts
TYPICAL PEDON: Cornhill gravelly clay loam. (Colors for moist conditions unless otherwise noted.)
Ap--0 to 9 inches; dark brown (10YR 3/3) gravelly clay loam; grayish brown (10YR 5/2) dry; weak medium subangular blocky structure; very hard, firm, slightly sticky and slightly plastic; common fine and few medium angular and subrounded volcanic rock fragments; common fine roots; few fine black concretions; calcareous, moderately alkaline, clear wavy boundary. (8 to 14 inches thick)
Bw--9 to 18 inches; very dark brown (10YR 2/2) heavy clay loam; weak medium and coarse subangular blocky structure; hard, firm, slightly sticky, slightly plastic; few fine dark oxide concretions; calcareous; moderately alkaline, gradual wavy boundary. (8 to 16 inches thick)
2Bw--18 to 30 inches; dark grayish brown (10YR 4/2) clay; coarse angular with slickensides and pressure faces moist, breaking to coarse granular or very weak fine subangular blocky structure on drying; firm, sticky, plastic, common fine black concretions; calcareous; moderately alkaline; gradual wavy boundary. (12 to 24 inches thick)
3C--30 to 36 inches; yellowish brown (10YR 5/4) gravelly clay; medium and coarse angular with slickensides and pressure faces moist, breaking to granular on drying; firm, slightly sticky, plastic; common fine black concretions; calcareous with common fine and medium calcium carbonate concretions; moderately alkaline; clear wavy boundary. (6 to 12 inches thick)
4C--36 to 50 inches; yellowish brown (10YR 5/4) gravelly clay; massive, firm, slightly sticky, slightly plastic, common fine dark oxide concretions; calcareous.
TYPE LOCATION: St. Croix, V.I., 205 feet east and 85 feet north of the southwest corner of a pasture fence which is 0.3 mile south of a windmill at Longford's headquarters or .46 mile south of the public road entrance.
RANGE IN CHARACTERISTICS: Thickness of solum ranges from 16 to 30 inches. Profile is calcareous throughout with secondary lime present in the lower horizons. Sandy and gravelly lenses may occur in any horizon or mixed throughout the profile.
The A horizon has hue of 10YR, value of 2 to 4 and chroma of 2 or 3. Texture ranges from gravelly clay loam to clay loam.
The Bw horizon has hue of 10YR, value of 2 to 4 and chroma of 2 or 3. Texture ranges from gravelly clay loam to clay loam.
The 2Bw horizon has hue of 10YR, value of 4 or 5 and chroma of 2 to 4. Texture is dominantly heavy clay loam in texture. Structure ranges from weak medium to weak coarse subangular blocky with few to common pressure faces. Consistence ranges from firm to friable.
The 3C and 4C horizons have hue of 10YR to 2.5Y, value of 4 to 7, and chroma of 3 to 5. They are typically stratified with clay or gravelly clay with numerous slickensides or pressure faces and the lower horizons grading into sand and gravel at depths of 48 to 68 inches.
COMPETING SERIES: The
Vives soils and the similar
Coamo soils. The Vives are more acid in the solum. The Coamo soils have B horizons with moderate structure and clay increase to qualify as argillic.
GEOGRAPHIC SETTING: The Cornhill soils occur on the nearly level coastal plains with slope gradients of 0 to 2 percent. The regolith consists of a younger mantle of moderately fine over older fine textured plastic marine sediments. The climate is semiarid. Rainfall ranges from 30 to 35 inches and mean annual temperature from 78 to 80 degrees F.
GEOGRAPHICALLY ASSOCIATED SOILS: These include the
San Anton in the same Great Group, the
Jaucas and in addition the
Coamo series. The San Anton soils have formed in recent moderately fine textured gravelly sediments along the inland stream channels. The Jaucas occur between the sea and the Cornhill soils and have coarse textured, calcareous light colored profiles.
DRAINAGE AND PERMEABILITY: Moderately well drained with slow runoff. Surface horizons have a moderate permeability and the underlying materials a slow permeability.
USE AND VEGETATION: The acreage largely used as pasture. Vegetation consists of native grasses, shrubs and Guineagrass where properly managed.
DISTRIBUTION AND EXTENT: St. Croix, V.I. Series is of minor extent.
SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: RALEIGH, NORTH CAROLINA
SERIES ESTABLISHED: St. Croix, V. I., 1932.
REMARKS: The Cornhill series was formerly classified in the Brown Forest intergrading to the Grumusols group.
Diagnostic horizons and features recognized in this pedon:
Ochric epipedon - zone from 0 to 9 inches (Ap that has mollic colors but is very hard and firm)
Cambic horizon - zone from 9 to 30 inches (Bw and 2Bw horizons)
Fluventic feature - More than 0.2 percent organic carbon at 50 inches.
National Cooperative Soil Survey
U.S.A.