LOCATION MAGENS VI+PR

Inactive Series
Rev. GA-BCD-JD
05/2017

MAGENS SERIES

The Magens series consists of very deep, well drained, moderately permeable soils on dissect volcanic uplands. They formed in highly weathered and leached volcanic rocks (saprolite). Slopes ranges from 30 to 50 percent. The mean annual precipitation is about 50 inches and the mean annual temperature is about 79 degrees F.

TAXONOMIC CLASS:

TYPICAL PEDON: Magens silty clay loam. (Colors for moist conditions unless otherwise stated.)

A1--0 to 7 inches; reddish brown (5YR 4/4) silty clay loam; moderate medium granular structure; friable, slightly sticky, slightly plastic; many fine roots; medium acid; clear smooth boundary. (6 to 8 inches thick)

A2--7 to 10 inches; yellowish red (5YR 4/6) silty clay loam; weak medium subangular blocky breaking to moderate medium granular structure; friable, slightly sticky, plastic; common fine roots; strongly acid; clear smooth boundary. (3 to 5 inches thick)

BA--10 to 17 inches; red (2.5YR 4/6) gravelly clay; weak medium subangular blocky breaking to moderate fine subangular structure; friable, slightly sticky, slightly plastic; few fine roots; weak stone line at 16 inches; small angular volcanic fragments and few cobbles 3 to 6 inches in diameter; strongly acid; clear smooth boundary. (5 to 9 inches thick)

Bt1--17 to 26 inches; red (10R 4/6) clay; weak coarse subangular blocky breaking to weak medium subangular blocky structure; friable, slightly sticky, slightly plastic; thin discontinuous clay films; few roots; strongly acid; gradual smooth boundary. (8 to 10 inches thick)

Bt2--26 to 42 inches; red (10R 4/6) clay; weak coarse subangular blocky breaking to weak fine and medium subangular blocky structure; friable, slightly sticky, slightly plastic; thin discontinuous clay films; few roots, strongly acid; gradual smooth boundary. (10 to 18 inches thick)

BC--42 to 49 inches; red (10R 4/6) silty clay loam; weak medium and coarse subangular blocky structure; slightly sticky, slightly plastic; thin discontinuous coatings; few fine roots; few fine pores; approximately 30 percent of horizon consists of saprolite; strongly acid; gradual wavy boundary. (5 to 9 inches thick)

C--49 to 84 inches; saprolite; variegated colors: red yellowish brown, gray and white with a rubbed color of red (10R 4/6); massive; few clay coatings on fracture planes.

TYPE LOCATION: St. Thomas, V. I., 200 feet east on the Jasmine road from the main entrance to the North Star Village housing development; 990 feet north of the Mountain Top. Photo No. 1237- 12-602.

RANGE IN CHARACTERISTICS: Thickness of solum varies from 35 to 60 inches. Reaction of the profile ranges from strongly acid to medium acid. Rock fragments range from 0 to 35 percent throughout.

The A horizon has hue of 7.5YR or 5YR, value of 3 or 4 and chroma of 2 to 6. Texture is silty clay loam, clay loam, or silty clay.

The Bt horizon has hue of 10R to 5YR, value of 4 and chroma of 6 or 8. Texture is dominantly clay. The structure of these horizons ranges from weak coarse to fine subangular blocky. Few subrounded stones, 12 to 24 inches in diameter of more resistant volcanic materials can be found scattered throughout the profiles.

The BC horizon has similar colors of the Bt horizon. Texture is silty clay or silty clay loam. Amount of saprolite ranges from 25 to 50 percent.

The C horizon has variegated colors and consists of saprolite.

COMPETING SERIES: These include the Coto, Matanzas, Catalina and Humatas series. The Coto soils are yellower (hues of 7.5YR), have weaker structure and lack clay films in the B horizon. The Matanzas soils, are darker (lower values) in color, have granular B horizons that lack clay films. The Catalina soils are more acid, and have lower (less than 50) percent base saturation. The Humatas soils are more acid, have B horizons with moderate structure and patchy clay films that qualify for argillic and in addition have lower percent base saturation.

GEOGRAPHIC SETTING: These soils occur on moderately steep to topography on side slopes of dissected volcanic uplands with slope gradients of 30 to 50 percent. The regolith consists of very highly weathered residuum of basic volcanic rocks with occasional stones or boulders of less weathered rocks. The climate is semi-arid tropical with annual precipitation ranging from 40 to 55 inches and mean annual temperature ranging from 78 to 80 degrees F.

GEOGRAPHICALLY ASSOCIATED SOILS: These include the Cramer, Isaac, Victory and Dorothea series. All these soils occur in similar topographic positions in the steep volcanic uplands. The Cramer soils are shallow (less than 20 inches) to hard volcanic rocks. The Isaac soils have dark colored (mollic) surface layers and are moderately deep (20 to 72 inches) to hard volcanic rocks. The Victory soils are yellower (10YR to 7.5YR hues) and have weakly developed (cambic) B horizons. The Dorothea soils are yellower (7.5YR to 10YR hues) and have B horizons with moderate structure and clay films.

DRAINAGE AND PERMEABILITY: Well drained, surface runoff is medium to rapid, permeability is moderate.

USE AND VEGETATION: Most of the areas are now in brush or brushy forest. Very few areas are used for cultivated crops or pasture. Some areas have been subdivided for housing developments.

DISTRIBUTION AND EXTENT: American Virgin Islands. Series is of minor extent.

SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: RALEIGH, NORTH CAROLINA

SERIES ESTABLISHED: St. Thomas, V. I., Dec. 1972.

REMARKS: This series occurs only in northern St. Thomas. Limited data shows base saturation to increase with depth and will exceed 50 percent. There will be a reclassification of the Magens series with the next OSED draft.

Diagnostic horizons and features recognized in this pedon:

Ochric epipedon - zone from 0 to 10 inches (A horizon)

Argillic horizon - zone from 17 to 42 inches (Argillic horizons)

National Cooperative Soil Survey
U.S.A.