LOCATION DERRICK CO+WYEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, frigid Typic Haplargids
TYPICAL PEDON: Derrick gravelly loam, grassland. (Colors are for dry soil unless otherwise noted.)
A--0 to 4 inches; light brownish gray (10YR 6/2) gravelly loam, dark grayish brown (10YR 4/2) moist; moderate fine granular structure; soft, very friable; 35 percent pebbles, mostly basalt; many dark colored magnetic mineral grains in the sand and silt fractions; neutral (pH 7.2); gradual smooth boundary. (2 to 6 inches thick)
Bt--4 to 14 inches; brown (7.5YR 5/3) very gravelly clay loam, dark brown (7.5YR 4/3) moist; weak medium prismatic structure parting to moderate fine subangular blocky; slightly hard, very friable, slightly plastic; peds are very hard; thin nearly continuous glossy coatings on faces of peds; glossy coatings in root channels; wax-like rims at the entrance of soil pores; 60 percent basalt pebbles; many dark magnetic mineral grains in the sand and silt fractions; mildly alkaline (pH 7.4); clear wavy boundary. (4 to 18 inches thick).
BCk--14 to 17 inches; brown (10YR 5/3) extremely gravelly loam, dark brown (10YR 4/3) moist; weak medium subangular blocky structure; soft, very friable; peds are slightly hard; a few thin glossy patches on faces of peds; 70 percent pebbles, mostly basalt; many dark magnetic mineral grains in the sand and silt fractions; visible secondary calcium carbonate occurring as concretions, in thin seams and streaks, and as coatings on rock fragments; calcareous; moderately alkaline (pH 8.0); gradual wavy boundary. (0 to 4 inches thick).
2Ck--17 to 60 inches; very gravelly sand. Some visible carbonate occurring as coatings on rock fragments; 40 percent pebbles, 20 percent cobble; most of the rock fragments and a high proportion of the sand are dark fragments of basalt, and this horizon has a dark gray cast on exposure.
TYPE LOCATION: Rio Grande County, Colorado; 1,500 feet west of the NE corner of sec. 2, T.37N., R.7E.
RANGE IN CHARACTERISTICS: mean annual soil temperature ranges 42 degrees to 45 degrees F. Mean summer soil temperature ranges 60 degrees
to 64 degrees F. Depth to uniformly calcareous material normally ranges from 6 to 20 inches and extends less than 2 inches into the Bt horizon. Depth to the sandy-skeletal 2C horizon and depth to base of the argillic horizon range from 11 to 20 inches. Depth to continuous subhorizons of visible secondary calcium carbonate and/or sulfate ranges from 8 to 30 inches, but these horizons are not strong enough to qualify as calcic or gypsic horizons. Mottling within the control section not due to segregation of lime ranges from no mottling to a few faint mottles with chroma of more than 2. Rock fragments are mainly 1/2 to 10 inches in diameter. The solum and C horizons when present, above the 2C horizon are uniform with only minor stratification.
The A horizon has hue from 5Y through 7.5YR, value of 5 through 7, 3 through 6 moist, and chroma from 1 through 4. It is neutral or mildly alkaline (1:5 dilution unbuffered organic dye).
The Bt horizon has hue of 5Y through 7.5YR, value of 5 through 7, 3 through 6 moist, and chroma of 1 through 6. It is typically loam, sandy clay loam, or clay loam with 18 to 35 percent clay, 20 to 55 percent silt, and 20 to 55 percent sand with less than 35 percent fine or coarser sand. This horizon ranges from neutral to moderately alkaline (1:5 dilution unbuffered organic dye).
The 2C horizon has hue of 5Y through 7.5YR. It is gravelly to extremely gravelly sand or loamy sand. This horizon is moderately alkaline or strongly alkaline (1:5 dilution unbuffered organic dye) and contains 3 to 14 percent calcium carbonate equivalent of the fine earth fraction.
COMPETING SERIES: There are no competing series in this family. The Preatorson and Zaba series have mesic soil temperatures.
GEOGRAPHIC SETTING: Derrick soils are on alluvial fans and valley side slopes. Slopes typically range from 0 to about 10 percent. These soils formed in moderately thin, calcareous, gravelly, medium to moderately fine textured alluvium overlying beds of gravelly or very gravelly coarse-textured alluvium. The mean annual precipitation is 6 to 9 inches with peak periods of precipitation in the spring and early summer months. Mean annual temperature is 40 degrees to 43 degrees F, and mean summer temperature is 59 degrees to 63 degrees F.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Graypoint and San Arcacio soils. Both of these soils have fine-loamy over sandy or sandy-skeletal control sections.
DRAINAGE AND PERMEABILITY: Well-drained; medium runoff; moderate permeability in the solum and rapid in the C horizon.
USE AND VEGETATION: These soils are used as native pastureland or for irrigated cropland. Principle native plants are threeawn, ring muhly, saltbush, catus, and rabbitbrush.
DISTRIBUTION AND EXTENT: San Luis Valley Area of Colorado. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Rio Grande County Area, Colorado, 1972.
REMARKS:
The superactive cation exchange activity class was added in 03/2003 to the taxonomic classification by the National Soil Survey Center on request of the Reno MLRA office, without review of the soil series property data. The remainder of this document has not been updated.