LOCATION HESSELBERG VIEstablished Series
TAXONOMIC CLASS: Clayey, mixed, superactive, isohyperthermic, shallow Petrocalcic Paleustolls
TYPICAL PEDON: Hesselberg clay. (Colors are for moist conditions.)
A1--0 to 7 inches; dark reddish brown (5YR 3/3) clay; strong fine and medium granular structure; firm, slightly sticky, slightly plastic; many fine and medium roots; about 5 percent, by volume, pebbles; slightly effervescent; slightly alkaline; clear smooth boundary. (4 to 8 inches thick)
A2--7 to 12 inches; dark reddish brown (5YR 3/3) clay; strong fine and medium granular structure; firm, slightly sticky, slightly plastic; many fine roots; about 10 percent, by volume, pebbles; slightly effervescent; slightly alkaline; clear smooth boundary. (2 to 4 inches thick)
Bk--12 to 17 inches; dark red (2.5YR 3/6) gravelly clay; weak fine and medium prismatic structure; firm, slightly sticky, slightly plastic; common fine roots; few medium wormcasts; common filaments of calcium carbonate; about 30 percent, by volume, pebbles; slightly effervescent; slightly alkaline; abrupt wavy boundary. (2 to 8 inches thick)
Bkm1--17 to 18 inches; reddish yellow (7.5YR 6/6), pinkish white (7.5YR 8/2), and very pale brown (10YR 8/4) partly silicified marl; massive; extremely hard; strongly effervescent; moderately alkaline; clear wavy boundary. (2 to 4 inches thick)
Bkm2--18 to 24 inches; white (7.5YR 8/1) partly silicified marl; massive extremely hard; strongly effervescent; moderately alkaline; clear wavy boundary. (2 to 8 inches thick)
2C--24 to 60 inches; very pale brown (10YR 8/3) gravelly sandy loam; massive; friable; many fine and medium nodules of calcium carbonate; about 20 percent, by volume, pebbles; strongly effervescent; moderately alkaline.
TYPE LOCATION: St. Croix Island, U.S. Virgin Islands. From Henry E. Rohlsen Airport terminal about 0.5 mile west on VI-64, about 0.1 mile southeast on unimproved lane, and about 50 feet west of lane in a wooded area. Fredriksted topographic quadrangle; lat. 17 degrees 42 minutes 4 seconds N.; long. 64 degrees 48 minutes 26 seconds W.; PRD 1940.
RANGE IN CHARACTERISTICS: Depth to the petrocalcic horizon ranges from 10 to 20 inches. Reaction is slightly alkaline to moderately alkaline in the A and B horizons, and moderately alkaline in the C horizon.
The A horizon has hue of 2.5YR to 10YR, value of 2 or 3, and chroma of to 2 or 3. Content of pebbles and cobbles composed of calcite ranges from 0 to 15 percent, by volume.
The Bk horizon has hue of 10R to 7.5YR, value of 3 or 4, and chroma of 3 to 6. Content of pebbles and cobbles composed of calcite ranges from 10 to 30 percent, by volume. Calcium carbonate masses, nodules, concretions, or filaments range from few to many.
The Bkm horizon is extremely hard, partly silicified marl.
The C or 2C horizon has hue of 5YR to 2.5YR, value of 4 to 8, and chroma of 1 to 8. Mottles in shades of white, yellow, or brown range from none to many. Texture is sandy loam, loam, or sandy clay loam in the fine-earth fraction. Calcium carbonate masses, nodules, filaments, or concretions range from few to many. Content of pebbles and cobbles composed of calcite ranges from 0 to 30 percent, by volume.
COMPETING SERIES: There are no competing series in the same family.
GEOGRAPHIC SETTING: Hesselberg soils are on ancient marine terraces. They formed in regolith that consists of fine-textured marine residuum. The slope ranges from 0 to 12 percent. The climate is tropical semiarid. The mean average air temperature ranges from 76 to 82 degrees F., and the mean annual precipitation is about 40 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These include the Arawak, Glynn, Hogensborg, and Sion soils. These soils do not have a petrocalcic horizon. In addition, Arawak soils are on higher positions and have loamy-skeletal particle-size control sections. Glynn and Hogensborg soils are on slightly lower alluvial fans and terraces and are very deep. Sion soils are on higher side slopes and valley floors, are very deep, and have coarse-loamy particle-size control sections.
DRAINAGE AND PERMEABILITY: Well drained; slow permeability.
USE AND VEGETATION: Most areas of Hesselberg soils are used for pasture or urban development. The vegetation consists of guinea grass and other native grasses and shrubs.
DISTRIBUTION AND EXTENT: St. Croix Island, U.S. Virgin Islands. They are not extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Raleigh, North Carolina
SERIES ESTABLISHED: St. Croix Island, U.S. Virgin Islands; 1932.
REMARKS: Diagnostic horizons and features recognized in this pedon include:
Mollic epipedon - zone from 0 to 12 inches (A and AB horizons).
Calcic horizon - zone from 12 to 17 inches (Bk horizon).
Petrocalcic horizon - zone from 17 to 24 inches (Bkm1 and Bkm2 horizons).
ADDITIONAL DATA: Characterization pedon - St. Croix Island, U.S. Virgin Islands; S64VI-10-4. Sample by NSSL, Lincoln NE., 9/1964.
MLRA: 273.
SIR: VI0009.