LOCATION COLOMEX NMEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, frigid Typic Haplustalfs
TYPICAL PEDON: Colomex gravelly silt loam - pine grassland. (Colors are for dry soil unless otherwise noted.)
A1--0 to 3 inches; brown (10YR 5/3) gravelly silt loam, very dark grayish brown (10YR 3/2) moist; weak fine granular structure; soft, very friable, slightly sticky and slightly plastic; few very fine and fine roots; common very fine interstitial pores; 15 percent pebbles, 5 percent cobbles; mildly alkaline (pH 7.4); clear smooth boundary. (2 to 4 inches thick)
A2--3 to 6 inches; brown (10YR 5/3) gravelly silt loam, very dark grayish brown (10YR 3/2) moist; weak fine subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; few very fine and fine roots; common very fine tubular pores; 15 percent pebbles, 5 percent cobbles; neutral (pH 7.0); clear smooth boundary. (0 to 3 inches thick)
2Bt1--6 to 12 inches; light brown (7.5YR 6/4) gravelly sandy clay loam, brown (7.5YR 4/4) moist; weak fine subangular blocky structure; slightly hard, firm, sticky and plastic; common very fine and fine roots; common very fine and fine pores; clay films bridging sand grains and coating rock fragments; 20 percent pebbles, 10 percent cobbles; neutral (pH 7.0); clear smooth boundary. (4 to 8 inches thick)
2Bt2--12 to 34 inches; brown (7.5YR 4/4) extremely cobbly sandy clay loam, brown (7.5YR 4/4) moist; moderate medium subangular blocky structure; slightly hard, friable, sticky and plastic; common very fine and fine roots; common very fine and fine pores; clay films bridging sand grains and coating rock fragments; 40 percent pebbles, 40 percent cobbles; neutral (pH 7.0); gradual wavy boundary. (19 to 33 inches thick)
3Bt3--34 to 60 inches; brown (7.5YR 4/4) very gravelly loamy sand, brown (7.5YR 4/4) moist; weak fine subangular blocky structure; soft, loose, nonsticky and nonplastic; few very fine and fine roots; common very fine and fine pores; clay films coating rock fragments; 40 percent pebbles, 10 percent cobbles; neutral (pH 7.0). (15 to 30 inches thick)
TYPE LOCATION: Rio Arriba County, New Mexico; approximately 25 yards south of P. Gallegos Memorial Park baseball field, in Chama, New Mexico. State plane coordinates 2,143,684 feet north and 402,105 feet east; 106 degrees, 35 minutes, 11 seconds west longitude; 36 degrees, 53 minutes, 40 seconds north latitude.
RANGE IN CHARACTERISTICS:
Soil moisture: The soil is moist in some parts of the SMCS November through April and July through August.
Soil temperature: 41 to 47 degrees F.
Control Section, Percent clay: 20 to 35 percent.
A horizon - Value: 4 or 5 dry, 3 or 4 moist.
Chroma: 2 or 3.
Rock fragments: 15 to 20 percent pebbles, 0 to 5 percent cobbles.
Bt horizon - Value: 4 to 6 dry, 4 or 5 moist.
Rock fragments: 25 to 40 percent pebbles, 10 to 40 percent cobbles, 0 to 5 percent stones on a weighted average.
COMPETING SERIES: These are the Crackercreek(WA), Laventana(NM), Olot(OR), Sawbuck(T)(MT), Security(CO), and Sheek(T)(CO) soils. Crackercreek soils have volcanic ash influenced surface layers 14 to 20 inches thick. Laventana soils have albic horizons. Olot and Security soils have lithic contacts at 20 to 40 inches. Sawbuck soils have less than 35 percent sand in the particle-size control section. Sheek soils have E horizons and are dominated by stones.
GEOGRAPHIC SETTING: Colomex soils are on terraces. These soils formed in alluvium derived from metamorphic and igneous rocks. Slopes are 0 to 3 percent. Elevation are 7,500 to 8,200 feet. Mean annual precipitation is 18 to 22 inches. The mean annual temperature is 40 to 45 degrees F, and the frost-free period is 80 to 100 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These soils are the Chamita, Doslomas, Dula, Encicado and Grava soils. Chamita, Doslomas and Encinado soils have more than 35 percent clay in the particle-size control section. Dula and Grava soils have a high water table.
DRAINAGE AND PERMEABILITY: Well drained; slow runoff; moderate permeability.
USE AND VEGETATION: Colomex soils are used for livestock grazing, woodland production, and urban development. The present vegetation is grasses, gambel oak, and ponderosa pine.
DISTRIBUTION AND EXTENT: North-central New Mexico. Series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Rio Arriba County, New Mexico, 1989. The series name is coined.
REMARKS: Diagnostic horizon and features recognized in this pedon are:
Ochric Epipedon - the zone from the surface to a depth of 6 inches (A horizon).
Argillic horizon - the zone from 6 to 34 inches (Bt horizon).
Mollic feature - ochric epipedon has color value less than 6 dry, and less than 4 moist.