LOCATION LONGBURN COEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, mesic Lithic Haplustalfs
TYPICAL PEDON: Longburn cobbly fine sandy loam, on a south facing, 6 percent slope in pinyon juniper woodland, at an elevation of 7,460 feet. (Colors are for dry soil unless otherwise noted.) The surface is covered by 15 percent gravel, 10 percent cobbles, 5 percent stones, and 1 percent boulders.
A1--0 to 1 inches; brown (7.5YR 5/4) cobbly fine sandy loam, dark brown (7.5YR 3/3) moist; weak fine granular structure; soft, loose, nonsticky and nonplastic; 15 percent gravel, 10 percent cobbles, 5 percent stones, and 1 percent boulders; neutral (pH 7.2); abrupt smooth boundary. (1 to 6 inches thick)
A2--1 to 4 inches; brown (7.5YR 5/4) very cobbly fine sandy loam, dark brown (7.5YR 3/4) moist; weak fine granular structure; soft, very friable, nonsticky and nonplastic; common very fine and many medium roots throughout; 20 percent gravel, 15 percent cobbles, 5 percent stones, and 1 percent boulders; neutral (pH 7.2); clear wavy boundary. (1 to 6 inches thick)
Bt1--4 to 12 inches; brown (7.5YR 5/4) very cobbly clay loam, brown (7.5YR 4/4) moist; moderate medium angular blocky structure; hard, friable, moderately sticky and moderately plastic; common very fine and common medium roots throughout; common very fine continuous tubular pores; many distinct continuous clay films on faces of peds and in pores; 20 percent gravel, 20 percent cobbles, 5 percent stones, and 1 percent boulders; slightly alkaline (pH 7.4); clear wavy boundary. (4 to 12 inches thick)
Bt2--12 to 17 inches; brown (7.5YR 5/4) very cobbly clay loam, brown (7.5YR 4/4) moist; moderate medium angular blocky structure; hard, friable, moderately sticky and moderately plastic; common very fine roots throughout; common very fine discontinuous tubular pores; many distinct continuous clay films on faces of peds and in pores; 25 percent gravel, 20 percent cobbles, 5 percent stones, and 1 percent boulders; slightly alkaline (pH 7.4); abrupt wavy boundary. (4 to 12 inches thick)
R--17 inches; slightly weathered Cliffhouse sandstone.
TYPE LOCATION: Montezuma County, Colorado; about 1/2 mile south of the fire tower on Whites Mesa, Mesa Verde National Park; Moccasin Mesa Colorado USGS quad; lat. 37 degrees 14 minutes 30 seconds N. and long. 108 degrees 23 minutes 28 seconds W., NAD27
RANGE IN CHARACTERISTICS:
Surface rock fragments: 5 to 20 percent gravel, 5 to 15 percent cobble, and 0 to 5 percent stones
Soil moisture regime: ustic bordering on aridic
Soil temperature regime: mesic
Mean annual soil temperature: 49 to 52 degrees F
Depth to lithic contact: 6 to 20 inches to hard sandstone
Lithology of rock fragments: sandstone
Particle-size control section:
Clay content: 20 to 35 percent
A horizon:
Hue: 7.5YR or 10YR
Value: 4 or 5 (3 or 4 moist)
Chroma: 3 or 4
Texture: loam or fine sandy loam
Rock fragments: more than 35 percent, predominantly gravel and cobble
Reaction: neutral or slightly alkaline
Bt horizon:
Hue: 7.5YR
Value: 4 or 5 (3 or 4 moist)
Chroma: 4 or 5
Texture: clay loam or sandy clay loam
Rock fragments: more than 35 percent, predominantly gravel and cobble
Calcium carbonate equivalent: 0 to 5 percent
Reaction: slightly alkaline or moderately alkaline
COMPETING SERIES: These are the Chunkmonk, Obeknob, and Timpoweap series. The Chunkmonk and the Timpoweap soils are derived from limestone. The Obeknob soils are derived from monzonite.
GEOGRAPHIC SETTING:
Parent material: colluvium, residuum, and reworked eolian material derived from sandstone
Landform: canyons and mesas
Slopes: 3 to 80 percent
Elevation: 6,800 to 7,800 feet
Mean annual temperature: 47 to 50 degrees F
Mean annual precipitation: 16 to 19 inches
Precipitation is fairly evenly distributed throughout the year with July and August being slightly wetter and June being slightly dryer.
Frost-free period: 130 to 150 days
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Romberg, Cragola, Arabrab and Morefield soils. Morefield and Romberg soils are very deep. Arabrab soils contain less than 35 percent rock fragments. Cragola soils lack an argillic horizon and are shallow over soft bedrock.
DRAINAGE AND PERMEABILITY: well drained, low to very high runoff, moderately slow permeability
USE AND VEGETATION: These soils are used for wildlife habitat. Vegetation is twoneedle pinyon, Utah juniper, muttongrass, Indian ricegrass, and Utah serviceberry.
DISTRIBUTION AND EXTENT: Southwest Colorado. LRR D, MLRA 36. This series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Cortez Area, Colorado, Parts of Dolores and Montezuma Counties 1997.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon: The zone from 0 to 4 inches. (A1 and A2)
Argillic horizon: The zone from 4 to 17 inches. (Bt1 and Bt2)
Lithic contact: at 17 inches (R)
Particle size control section: The zone from 4 to 17 inches. (Bt1 and Bt2)
Taxonomy version: Soil Taxonomy Second Edition, 1999