LOCATION SPROUL TXEstablished Series
TAXONOMIC CLASS: Very-fine, smectitic, thermic Vertic Paleustolls
TYPICAL PEDON: Sproul clay loam - rangeland. (Colors are for dry soil unless otherwise stated.)
A--0 to 6 inches; dark grayish brown (10YR 4/2) clay loam, very dark brown (10YR 2/2) moist; moderate fine and medium subangular blocky structure; hard, friable, sticky, plastic; common roots; about 5 percent by volume of igneous pebbles up to 3 inches in diameter; surface has many igneous pebbles mainly 1/2 to 2 inches in diameter; slightly acid; abrupt wavy boundary. (3 to 9 inches thick)
Bt1--6 to 17 inches; dark grayish brown (10YR 4/2) clay, very dark grayish brown (10YR 3/2) moist; moderate medium angular blocky structure; extremely hard; very firm; very sticky; very plastic; few fine Fe-Mn accretions, few nonintersecting slickensides; few very dark brown coatings on outside of peds; shiny ped faces; few igneous pebbles; common roots; slightly acid; gradual wavy boundary. (8 to 15 inches thick)
Bt2--17 to 26 inches; brown (7.5YR 4/2) clay, dark brown (7.5YR 3/2) moist; moderate medium angular blocky; few nonintersecting slickensides; extremely hard, very firm, very sticky and very plastic; few roots; few very dark brown coatings on outside of peds; few weakly cemented Fe-Mn accretions; about 5 percent by volume of igneous pebbles and cobbles; slightly acid; abrupt irregular boundary. (5 to 15 inches thick)
R--26 to 38 inches; light gray (5Y 7/2); light olive gray (5Y 6/2) moist; fractured strongly cemented tuffaceous bedrock in 1 to 3 inch layers; hardness of 1 to 1.5 Moh's scale; patchy dark brown clay coatings on fragments; few fine roots in crevices.
TYPE LOCATION: Jeff Davis County, Texas; in a pasture 3 1/2 miles east and 1 1/2 miles north on McDonald Observatory.
RANGE IN CHARACTERISTICS:
Soil moisture: Typic ustic moisture regime.
Solum thickness: 21 to 40 inches thick to tuffaceous bedrock.
Rock fragments: contains from a few to about 30 percent by volume of coarse fragments, mostly less than 3 inches in size. The volume of coarse fragments typically increases with depth.
A horizon
Hue: 7.5YR or 10YR
Value: 3 or 4
Chroma: 2
Texture: clay loam, silty clay loam, or silty clay.
Reaction: neutral or slightly acid.
Bt
Color: same colors as the A horizon
Texture: clay
Clay content: 60 to 75 percent
Reaction: neutral or slightly acid.
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Sproul soils occur on divides and tablelands of igneous hills and mountains. The surface gradients range from 0 to 5 percent. Elevations range from 5,000 to 6,200 feet. The underlying bedrock is weakly to strongly cemented tuff, ash or other igneous materials having the hardness and consistency of chalk, but more gritty and lacking carbonates. They are in a semiarid continental climate with annual precipitation of 14 to 25 inches. Mean annual soil temperatures range from 59 to 65 degrees F.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Kokernot, Liv and Mainstay soils of the competing series, and Brewster soils. Brewster soils lack an argillic horizon, are shallow to igneous bedrock, and contain more than 35 percent coarse fragments.
DRAINAGE AND PERMEABILITY: Well drained; slow to medium runoff; slow permeability.
USE AND VEGETATION: Use is mainly as native range. Vegetation is mainly mid to tall grasses with scattered juniper and pinion pines.
DISTRIBUTION AND EXTENT: At the higher elevations of the Davis Mountains mainly above 5,500 feet elevation. The series is of minor extent. MLRA 42.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: Jeff Davis County, Texas; 1971.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - 0 to 26 inches.
Abrupt textural change - at 6 inches.
Argillic horizon - 6 to 26 inches.
Classified according to Keys to Soil Taxonomy Tenth Edition, 2006
The precipitation range of 14 to 25 inches covers an Aridic ustic to Typic ustic moisture regime. Reclassified as a Vertic Paleustolls in 2007.