LOCATION TOCAL NMEstablished Series
TAXONOMIC CLASS: Clayey, mixed, superactive, mesic, shallow Typic Haplustalfs
TYPICAL PEDON: Tocal very fine sandy loam, forested. (Colors are for dry soil unless otherwise noted.)
A--0 to 5 inches; grayish brown (10YR 5/2) very fine sandy loam, very dark grayish brown (10YR 3/2) moist; weak fine granular structure; soft, very friable, nonsticky and nonplastic; many fine roots; many interstitial pores; neutral; abrupt smooth boundary. (1 to 6 inches thick)
Bt1--5 to 8 inches; reddish brown (5YR 5/3) clay loam, reddish brown (5YR 4/3) moist; fine subangular blocky structure; hard, firm, sticky and plastic; many fine roots; few very fine interstitial pores; thin continuous clay films on faces of peds; neutral; abrupt smooth boundary. (1 to 5 inches thick)
Bt2--8 to 11 inches; reddish brown (5YR 5/3) clay, reddish brown (5YR 4/3) moist; moderate coarse prismatic structure parting to moderate medium subangular blocky; hard, firm, sticky and plastic; many medium roots; few very fine tubular pores; thick continuous dark reddish brown (5YR 3/3) clay films on faces of peds; neutral; clear smooth boundary. (2 to 5 inches thick)
2Ct--11 to 14 inches; light brown (7.5YR 6/4) silt loam, brown (7.5YR 4/4) moist; massive; hard, friable, sticky and plastic; many medium roots; few very fine tubular pores; a few reddish brown (5YR 4/4) clay fillings in pores; neutral; abrupt smooth boundary. (1 to 4 inches thick)
2Cr--14 to 24 inches; moderately cemented rhyolitic tuff bedrock.
TYPE LOCATION: Los Alamos County, New Mexico; 750 feet west and 700 feet south of the center of section 17, T. 19 N., R. 6 E, Latitude 35 degrees 52 minutes 37 seconds N; Longitude 106 degrees 19 minutes 51 seconds W, NAD 27.
RANGE IN CHARACTERISTICS:
Soil Moisture: The soil moisture control section (SMCS) is moist in all parts from January to May and intermittently moist in some part from June to December. The SMCS is dry in some part 40 to 60 percent of the time when the soil temperature at 20 inches (50 cm) is above 41 degrees F. The soil moisture regime is typic ustic.
Depth to bedrock: 8 to 20 inches
Volcanic glass content in the upper part: 10 to 20 percent in the coarse silt plus sand fraction
A horizon
Hue: 7.5YR or 10YR
Value: 4 to 6 dry, 2 to 4 moist
Chroma: 2 or 3
Clay content: 8 to 18 percent
Pararock fragments: 5 to 10 percent paragravel
B horizon
Hue: 7.5YR or 5YR
Value: 4 to 6 dry, 3 or 4 moist
Chroma: 3 to 6
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Tocal soils are on shoulders of interfluves on undulating plateaus and mesas. They formed in material weathered from tuff. Slopes are 3 to 8 percent. Elevations are 6,900 to 8,000 feet. Mean annual precipitation is 16 to 18 inches. Mean annual temperature is 45 to 47 degrees F. The frost-free season is 120 to 140 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Carjo and Frijoles soils. Carjo soils are moderately deep to bedrock. Frijoles soils are loamy-skeletal.
DRAINAGE AND PERMEABILITY: Well drained; medium runoff; moderately slow or slow permeability.
USE AND VEGETATION: These soils are used mainly for timber and building sites. Present vegetation is ponderosa pine, Kentucky bluegrass, and mountainmahogany.
DISTRIBUTION AND EXTENT: Northcentral New Mexico. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Sandoval County Area, Los Alamos County, New Mexico, 1981.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon: The zone from 0 to 5 inches. (A horizon)
Argillic horizon: The zone from 5 to 11 inches. (Bt horizon)
Paralithic contact: Tuff at 14 inches. (2Cr layer)
In February 2002 the lithic contact was changed to a paralithic contact, the taxonomic class was changed from Lithic Haplustalfs to shallow Typic Haplustalfs, the temperature regime was changed from frigid to mesic, and the CEA class was changed from active to superactive. These changes were recommended following fieldwork on the Bandelier National Monument.
Classified according to Soil Taxonomy Second Edition, 1999.
ADDITIONAL DATA: Clay mineralogy determined by National Soil Survey Laboratory, Sample No. R74-296.