LOCATION SILCAT NMEstablished Series
TAXONOMIC CLASS: Fine, mixed, superactive, mesic Aridic Haplusterts
TYPICAL PEDON: Silcat clay loam--in rangeland on a south-facing convex slope of 8 percent at an elevation of 7,410 feet. (Colors are for dry soils unless otherwise noted.)
A--0 to 2 inches; light olive brown (2.5Y 5/6) clay loam, brown (10YR 4/3) moist; strong medium granular structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine and fine roots; common fine irregular pores; slightly alkaline (pH 7.5); abrupt smooth boundary. (2 to 3 inches thick)
2BC--2 to 7 inches; light olive brown (2.5Y 5/4) clay, olive brown (2.5Y 4/4) moist; moderate medium subangular blocky structure; hard, firm, sticky and plastic; many very fine and fine roots; few fine irregular pores; common pressures faces on faces of peds; cracks 0.75 inches wide extend from 2 inches to 38 inches deep, upper part of some cracks are filled with surface material; strongly effervescent; moderately alkaline (pH 8.0); clear smooth boundary. (0 to 5 inches thick)
2BCss1--7 to 18 inches; light olive brown (2.5Y 5/4) clay, olive brown (2.5Y 4/4) moist; strong medium prismatic structure; extremely hard, extremely firm, very sticky and very plastic; common very fine and fine roots; few fine tubular pores; many pressure faces on faces of peds; few slickensides; 0.75 inch wide cracks; strongly effervescent; moderately alkaline (pH 8.1); clear smooth boundary. (The combined thickness of the BCss horizon is 10 to 58 inches.)
2BCss2--18 to 38 inches; light olive brown (2.5Y 5/4) clay, olive brown (2.5Y 4/4) moist; massive; extremely hard, extremely firm, very sticky and very plastic; common very fine and fine roots; few fine tubular pores; many slickensides up to 3 inches in diameter are tilted 40 degrees from the horizontal; 0.75 inch wide cracks; strongly effervescent; moderately alkaline (pH 8.2); gradual smooth boundary. (The combined thickness of the BCss horizon is 10 to 58 inches.)
2Bk--38 to 65 inches; light olive brown (2.5Y 5/4) clay, olive brown (2.5Y 4/4) moist; massive; extremely hard, extremely firm, very sticky and very plastic; few very fine and fine roots; few fine tubular pores; strongly effervescent; calcium carbonate occurs as few very fine irregular soft filaments and soft masses; moderately alkaline (pH 7.9). (0 to 43 inches thick)
TYPE LOCATION: McKinley County, New Mexico; Upper Galestina Canyon Quadrangle; about 1.4 miles northwest of Upper Galestina Reservoir No. 1A; 108 degrees 39 minutes 54 seconds west longitude, 35 degrees 00 minutes 2 seconds north latitude.
RANGE IN CHARACTERISTICS:
Soil Moisture: The SMCS is usually moist, in all parts, for less than 90 cumulative days from April through October. It is usually dry, in some part, for more than 120 cumulative days during the same period. It is continuously moist in some part November through April, but not moist in all parts for 45 consecutive days from January through April. The period of maximum precipitation is July through October. The soil is driest during May and June. Aridic ustic moisture regime.
Soil Temperature: 48 to 55 degrees F
Particle-size control section: 45 to 55 percent clay
Cracks: Some cracks extend from the surface but most extend from 2 to 40 inches. (Self mulching surface)
Slickensides and pressure faces: Mostly occur from 5 to 40 inches deep.
A horizon:
Hue: 2.5Y or 10YR
Chroma: 4 or 6 dry, 2 or 3 moist
Rock fragments: 0 to 5 percent sandstone gravel or channers.
2BCss horizons:
Value: 4 or 5 dry, 2 or 4 moist
Chroma: 2 or 4 moist
2Bk horizon:
Value: 4 or 5 dry
Chroma: 2 or 4 dry or moist
COMPETING SERIES: These are the Moriartche (NM) soils. Moriartche soils have hues of 2.5YR or 5YR throughout the substratum.
GEOGRAPHIC SETTING: The Silcat soils formed in alluvium, slope alluvium, fan alluvium, and stream alluvium derived from shale (Mancos shale--Cretaceous Era) and are on stream terraces on valley floors, alluvial fans on valley sides, and footslopes of hills. Slopes are 0 to 10 percent. Elevations range from 6,800 to 7,500 feet. The mean annual temperature is 46 to 53 degrees F., and the mean annual precipitation is 13 to 16 inches. The frost free period is 100 to 135 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Toldohn and Vessilla soils on escarpments of mesas and cuestas; the proposed Parkelei and Evpark soils on summits and dipslopes of mesas and cuestas; and the proposed Galzuni and Bryway soils on summits and dipslopes of mesas and cuestas, and footslopes of hills. Toldohn and Vessilla are shallow to shale and sandstone, respectively. Evpark and Bryway soils are moderately deep to sandstone and shale, respectively. Parkelei soils are fine-loamy and the Galzuni soils have an argillic horizon.
DRAINAGE AND PERMEABILITY: Well drained, low runoff on slopes less that 2 percent and very high runoff on slopes greater then 2 percent, very slow permeability.
USE AND VEGETATION: This series is used for rangeland. Present vegetation is western wheatgrass, blue grama, rubber rabbitbrush, broom snakeweed, winterfat, pingue, and Russian thistle. Although big sagebrush does not generally occur on this soil it is the dominant shrub on the geographically associated soils.
DISTRIBUTION AND EXTENT: West central New Mexico. MLRA 35, LRR-D. This series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: McKinley County Area, New Mexico; McKinley County and Parts of Cibola and San Juan Counties, 2001.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon: The zone from 0 to 2 inches. (A horizon)
Vertic properties: Slight gilgai, cracks 0.75 inches wide extending from 2 to 38 inches, and slickensides occurring from 7 to 38 inches (2BCss1 and 2BCss2 horizons). Cracks are open greater than 90 days but less than 150 cumulative days in most years. (Discrepancies between moisture regime of surrounding soils and period of open cracks are under study. The moisture regime of surrounding soils was used for classification until study results are received.)
Classified according to Soil Taxonomy Second Edition, 1999.
ADDITIONAL DATA:
This pedon was sampled as Silkie (NSSL# S88NM-031-10) 6/23/88. After reviewing the lab data and field notes, it was decided to propose a new series and place it in the Vertisol order. (The ratio of fine clay to total clay and the lack of oriented clay in the cross section slides indicated this soil did not have an argillic horizon. The Silkie soil is classified as a Vertic Haplustalfs. As a result the classification and horizon designation were changed to reflect the vertic properties.