LOCATION PEGASUS NMEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, mesic Lithic Haplustalfs
TYPICAL PEDON: Pegasus extremely cobbly loam--on a backslope of a low hill sloping 28 percent to the west (280 degrees) at 6,914 feet elevation-pinyon-juniper forestland. (Colors are for dry soil unless otherwise noted. When described on August 29, 2001, the soil was moist throughout.) Surface is covered with 35 percent gravel, 35 percent cobbles and 4 percent stones. A thin mat of pinyon needles exists in some areas.
A--0 to 4 inches; dark brown (10YR 3/3) extremely cobbly loam, very dark grayish brown (10YR 3/2) moist; weak fine granular structure; soft, loose, slightly sticky and slightly plastic; few medium, common fine, and common very fine roots; few medium and few fine tubular pores; 30 percent gravel, 30 percent cobbles, and 4 percent stones; neutral (pH 6.8); clear smooth boundary. (2 to 5 inches thick)
Bt1--4 to 10 inches; dark yellowish brown (10YR 4/4) cobbly loam, brown (10YR 4/3) moist; moderate medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; few medium, few fine, and few very fine roots; few medium and few fine tubular pores; common faint clay films on faces of peds; 15 percent gravel and 10 percent cobbles; neutral (pH 7.0); clear smooth boundary. (3 to 8 inches thick)
Bt2--10 to 14 inches; brown (7.5YR 5/4) very gravelly clay loam, brown (7.5YR 4/4) moist; moderate fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; few medium, few fine, and few very fine roots; few medium and few fine tubular pores; common distinct clay films on faces of peds; 40 percent gravel and 15 percent cobbles; neutral (pH 6.8); abrupt wavy boundary. (3 to 7 inches thick)
R--14 to 24 inches; indurated monzonite bedrock.
TYPE LOCATION: Santa Fe County, New Mexico; about 4.5 miles south-southeast of Madrid, New Mexico; USGS Golden 7.5 minute topographic quadrangle; Latitude 35 degrees 20 minutes 48.1 seconds North and Longitude 106 degrees 07 minutes 37.6 seconds West, NAD 27.
RANGE IN CHARACTERISTICS:
Soil moisture - The soil moisture control section is moist in all parts during the 60 days following the winter solstice. It is moist in some part less than 40 percent and moist in all parts less than 25 percent of the time when the soil temperature at 20 inches is above 41 degrees F. The soils are driest in May and June. The soil moisture regime is ustic bordering on aridic.
Average annual soil temperature - 49 to 51 degrees F.
Depth to base of the argillic horizon - 10 to 20 inches
Depth to lithic contact - 10 to 20 inches
Lithology of rock fragments: monzonite
Particle-size control section (weighted averages)
Silicate clay content: 25 to 35 percent
Sand content: 25 to 45 percent
Fine sand or coarser content: 20 to 40 percent
Rock fragment content: 35 to 60 percent
A horizon
Hue: 7.5YR or 10YR
Value: 3 to 5 dry, 2 to 4 moist
Chroma: 2 to 4, dry or moist
Clay content: 15 to 25 percent
Rock fragments: total range is 60 to 80 percent
25 to 40 percent gravel
25 to 35 percent cobbles
3 to 5 percent stones
Bt1 horizon
Hue: 7.5YR or 10YR
Value: 4 to 6 dry, 3 or 4 moist
Chroma: 2 to 6, dry or moist
Texture: cobbly loam, cobbly clay loam, or gravelly clay loam
Clay content: 25 to 35 percent
Rock fragment content: total range is 15 to 35 percent
10 to 25 percent gravel
5 to 15 percent cobbles
Bt2 horizon
Hue: 7.5YR or 10YR
Value: 5 or 6 dry, 3 or 4 moist
Chroma: 4 or 6, dry or moist
Texture: very gravelly clay loam, very cobbly loam, or very cobbly clay loam
Clay content: 25 to 35 percent
Rock fragment: total range is 35 to 60 percent
25 to 40 percent gravel
10 to 20 percent cobbles
COMPETING SERIES: These are the
Chunkmonk,
Longburn,
Nees, and
Timpoweap series.
Chunkmonk soils have a calcic horizon with 15 to 38 percent calcium carbonate equivalent.
Longburn soils have rock fragments of sandstone.
Nees soils have more than 35 percent rock fragments throughout the argillic horizon.
Timpoweap soils have rock fragments of limestone and have secondary carbonates.
GEOGRAPHIC SETTING: Pegasus soils are on beveled summits, shoulders, and backslopes of low hills. They formed in slope alluvium and colluvium derived from Tertiary age monzonite. Slopes are 20 to 50 percent. Elevation ranges from 5,700 to 7,700 feet. The mean annual precipitation is 13 to 15 inches with about 45 percent falling as rain from high-intensity convective thunderstorms between July and September. The mean annual air temperature is 48 to 50 degrees F. The frost-free period is 140 to 160 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Pedregal and Wandurn soils. Pedregal soils are very deep, have calcic horizons, and occur on fan remnants. Wandurn soils are very deep, have mollic epipedons, and are on south-facing backslopes of mountains.
DRAINAGE AND PERMEABILITY: Well drained; high surface runoff; permeability is moderately slow.
USE AND VEGETATION: Pegasus soils are used for forestland products, recreation, and wildlife habitat. The historic climax vegetation is twoneedle pinyon, oneseed juniper, mountain mahogany, blue grama, and sideoats grama. The ecological site is Pinus edulis-Juniperus monosperma/Cercocarpus montanus-Cercocarpus nauseosus/Bouteloua gracilis(F036XB135NM).
DISTRIBUTION AND EXTENT: Pegasus soils are of small extent on the Mexican Highlands section of the Basin and Range physiographic province in northcentral New Mexico. The MLRA is 36.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Santa Fe County, New Mexico; Santa Fe Area Soil Survey Update; 2008. The name Pegasus is taken from the name of a gold mine in the Ortiz Mountains.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - The zone from the soil surface to a depth of about 4 inches. (A horizon)
Argillic horizon - The zone from 4 to about 14 inches. (Bt1 and Bt2 horizons)
Lithic contact - Indurated monzonite bedrock at 12 inches. (R layer)
Taxonomic version: Classified according to Keys to Soil Taxonomy, Tenth Edition, 2006.
This series was named Obeknob when originally proposed.