LOCATION DOROTHEA VIEstablished Series
TAXONOMIC CLASS: Fine, vermiculitic, isohyperthermic Typic Haplustalfs
TYPICAL PEDON: Dorothea clay loam (Colors for moist conditions.)
A--0 to 6 inches; dark brown (10YR 4/3) clay loam; moderate medium and coarse granular structure; friable, slightly plastic; many fine and medium roots, few coarse roots; many medium and coarse interstitial pores; many medium and coarse worm casts; about 5 percent, by volume, gravel; slightly acid; clear smooth boundary. (4 to 8 inches thick)
Bt1--6 to 11 inches; brown (10YR 5/6) clay loam; moderate medium subangular blocky structure; firm, slightly sticky, moderately plastic; common fine and medium roots; many fine and medium vesicular and tubular pores; few fine and medium wormcasts; few fine faint clay films on faces of peds; few pressure faces on vertical and horizontal faces of peds; about 5 percent, by volume, pebbles; slightly acid; clear smooth boundary.
Bt2--11 to 19 inches; yellowish brown (10YR 5/6) clay; moderate medium and coarse subangular blocky structure; very firm, slightly sticky, moderately plastic; common very fine and fine roots; few fine worm casts; few fine faint clay films on faces of peds; few pressure faces on vertical and horizontal faces of peds; about 5 percent, by volume, pebbles; slightly acid; clear smooth boundary. (Combined thickness of the Bt horizon is 10 to 17 inches)
B/C--19 to 30 inches; strong brown (7.5YR 5/6) clay loam; weak medium and coarse subangular blocky structure; firm, slightly sticky, slightly plastic; few very fine and fine roots; about 25 percent, by volume, saprolite; about 10 percent, by volume, pebbles; few fine iron-manganese concretions; slightly acid; clear smooth boundary. (9 to 12 inches thick)
C--30 to 60 inches; strong brown (7.5YR 5/6) saprolite that has a clay loam texture; massive; friable, slightly sticky, slightly plastic; about 10 percent, by volume, pebbles; slightly acid.
TYPE LOCATION: St. Thomas Island, U.S. Virgin Islands. About 1,000 feet west of the intersection of VI-33 and VI-40 (Liliendal Junction) on VI-33, and about 75 feet south of VI-33. Central St. Thomas topographic quadrangle; lat. 18 degrees 21 minutes 18 seconds N.; long. 64 degrees 57 minutes 22 seconds W.; PRD 1940.
RANGE IN CHARACTERISTICS: Thickness of the solum ranges from 24 to more than 60 inches. Reaction ranges from slightly acid to neutral throughout the profile.
The A horizon has hue of 7.5YR or 10YR, value of 3 or 4, and chroma of 2 to 4. Texture is clay loam or clay in the fine-earth fraction. Content of gravels, pebbles, and cobbles ranges from 0 to 30 percent by volume.
The Bt horizon has hue of 7.5YR or 10YR, value of 4 to 6, and chroma of 4 to 8. Texture is clay loam or clay in the fine-earth fraction. Content of pebbles and cobbles ranges from 0 to 30 percent by volume.
The B/C horizon has hue of 7.5YR to 2.5Y, value of 3 to 6, and chroma of 2 to 8. Texture is loam, sandy clay loam, or loam in the fine-earth fraction. The content of saprolite ranges from 20 to 40 percent by volume. Content of pebbles and cobbles ranges from 0 to 30 percent by volume.
The C horizon is saprolite. It has hue of 7.5YR to 2.5Y, value of 4 or 5, and chroma of 2 to 6. Texture is loam, sandy clay loam, or clay loam in the fine-earth fraction. Content of pebbles and cobbles ranges from 0 to 30 percent, by volume.
COMPETING SERIES: There are no competing series in this family.
GEOGRAPHIC SETTING: The Dorothea soils are on summits and sideslopes of volcanic hills and mountains (Louisenhoj Formation). The slope ranges from 20 to 90 percent. The climate is tropical semiarid. The average annual air temperature ranges from 76 to 82 degrees F., and the mean annual precipitation is about 40 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These include the Cramer, Fredriksdal, Maho Bay, Southgate, Susannaberg, and Victory soils. All of these soils are on similar positions as Dorothea soils. Cramer, Fredriksdal, Maho Bay, and Susannaberg soils are shallow and have Mollic epipedons. Southgate soils are shallow and have loamy-skeletal particle-size control sections. Victory soils are moderately deep and have loamy-skeletal particle-size control sections.
DRAINAGE AND PERMEABILITY: Well drained; slow permeability.
USE AND VEGETATION: Most areas are in urban areas. Some areas are in protected natural successional forest species.
DISTRIBUTION AND EXTENT: St. Thomas Island, U.S. Virgin Islands. They are not extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Raleigh, North Carolina
SERIES ESTABLISHED: St. Thomas Island, U.S. Virgin Islands, 1965.
REMARKS: Diagnostic horizons and features recognized in this pedon include:
Ochric epipedon - the zone from 0 to 6 inches (A horizon)
Argillic horizon - the zone from 6 to 19 inches (Bt horizons)
ADDTIONAL DATA: Characterization pedon - St. Thomas Island, U.S. Virgin Islands; S64VI-30-1. Sample by NSSL, Lincoln NE., 1964.
MLRA: 271.
SIR: VI0006.