LOCATION ISOLATION COEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, frigid Alfic Argiustolls
TYPICAL PEDON: Isolation gravelly sandy loam, on a south facing, concave, 7 percent slope in forest at an elevation of 8,160 feet. (Colors are for dry soil unless otherwise noted.) When described on July 19, 1995 the soil was moist throughout. The surface is covered by 2 percent stones, 5 percent cobbles, and 25 percent gravel.
Oi--0 to 1 inches; slightly decomposed needles, moss and twigs.
A1--1 to 6 inches; very dark grayish brown (10YR 3/2) gravelly sandy loam, very dark brown (10YR 2/2) moist; moderate medium granular structure; soft, very friable, nonsticky and nonplastic; 25 percent gravel, 5 percent cobbles and 2 percent stones; slightly acid (pH 6.4); abrupt smooth boundary.
A2--6 to 11 inches; dark grayish brown (10YR 4/2) very gravelly sandy loam, very dark grayish brown (10YR 3/2) moist; weak fine granular structure; soft, very friable, nonsticky and nonplastic; 30 percent gravel, 10 percent cobbles and 10 percent stones; neutral (pH 6.6); abrupt wavy boundary. (combined thickness of A horizons is 10 to 16 inches)
E and Bt--11 to 24 inches; light gray (10YR 7/2) extremely cobbly sandy loam, light brownish gray (10YR 6/2) moist (E); weak fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; lamellae of yellowish brown (10YR 5/4) extremely cobbly sandy loam, dark yellowish brown (10YR 4/4) moist (Bt); slightly hard, very friable, slightly sticky and slightly plastic; lamellae are continuous, nearly horizontal, .1 to .5 cm thick and have total thickness of 3.3 cm; 40 percent gravel and 30 percent cobbles; neutral (pH 6.8); abrupt smooth boundary. (10 to 18 inches thick)
Bt and E--24 to 33 inches; yellowish brown (10YR 5/4) extremely gravelly sandy loam, dark yellowish brown (10YR 4/4) moist (Bt); moderate medium subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; pale brown (10YR 6/3) extremely gravelly sandy loam, brown (10YR 4/3) moist (E); soft, very friable, nonsticky and nonplastic, lamellae are continuous, nearly horizontal, .5 to 1 cm thick and have total thickness of 16 cm; 50 percent gravel and 15 percent cobbles; neutral (pH 6.6); abrupt smooth boundary. (8 to 18 inches thick)
2BC--33 to 39 inches; yellowish brown (10YR 5/4) extremely gravelly coarse sand, dark yellowish brown (10YR 4/4) moist; weak fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; 65 percent gravel; neutral (pH 7.0); abrupt smooth boundary. (4 to 8 inches thick)
2C1--39 to 51 inches; light yellowish brown (10YR 6/4) very gravelly coarse sand, yellowish brown (10YR 5/4) moist; weak fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; 50 percent gravel; neutral (pH 6.8); abrupt smooth boundary. (8 to 12 inches thick)
3C2--51 to 72 inches; brownish yellow (10YR 6/6) and yellowish brown (10YR 5/4) loamy coarse sand, yellowish brown (10YR 5/6) and dark yellowish brown (10YR 4/4) moist; weak fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; 10 percent boulders; neutral (pH 7.0).
TYPE LOCATION: Larimer County, Colorado; about .6 miles west of Moraine Park Visitor Center, Rocky Mountain National Park; about 1200 feet west and 2000 feet south of the NE corner of sec. 32, T. 5 N., R. 73 W.; Long Peak USGS quad; lat. 40 degrees 21 minutes 36 seconds N. and long. 105 degrees 35 minutes 44 seconds W., NAD 1927
RANGE IN CHARACTERISTICS: (Depths given are measured from the mineral soil surface)
Soil moisture regime: ustic moisture regime
Mean annual soil temperature: 40 to 44 degrees F
Thickness of mollic epipedon: 10 to 16 inches
Depth to argillic horizon: 10 to 24 inches
Depth to the base of the argillic: 28 to 50, total thickness of lamellae is 6 to 12 inches
Depth to lithologic discontinuity with very coarse and coarse sand: 28 to 50 inches
Particle-size control section (weighted average):
Clay content: 8 to 18 percent
Sand content: 55 to 75 percent
Rock fragments: 45 to 65 percent, dominantly gravel and cobbles
Mica content: 15 to 30 percent (by grain count)
A horizons:
Hue: 7.5YR or 10YR
Value: 3 to 5 dry, 2 or 3 moist
Chroma: 1 to 3
Texture: gravelly sandy loam, very gravelly sandy loam
Clay content: 8 to 18 percent
Rock fragments: 15 to 60 percent
Base saturation: 60 to 100 percent
Reaction: slightly acid or neutral
E and Bt horizon: (unless specified, properties apply to both E part and Bt part of horizon)
Hue: 7.5YR or 10YR
Value: 6 or 7 dry, 4 or 5 moist (E)
Value: 5 or 6 dry, 4 or 5 moist (Bt)
Chroma: 2 to 4 (E)
Chroma: 3 to 6 (Bt)
Texture: extremely cobbly sandy loam, extremely cobbly coarse sandy loam
Clay content: 10 to 20 percent
Rock fragments: 35 to 70 percent, dominantly cobbles and gravel
Base saturation: 60 to 100 percent
Reaction: slightly acid or neutral
Bt and E horizon: (unless specified, properties apply to both Bt part and E part of horizon)
Hue: 7.5YR or 10YR
Value: 5 or 6 dry, 4 or 5 moist (Bt)
Value: 6 or 7 dry, 4 to 6 moist (E)
Chroma: 3 to 6 (Bt)
Chroma: 2 to 4 (E)
Texture: extremely cobbly sandy loam, extremely gravelly sandy loam,
Clay content: 10 to 20 percent
Rock fragments: 60 or 80 percent, dominantly cobbles and gravel
Base saturation: 60 to 100 percent
Reaction: slightly acid or neutral
2BC horizon:
Hue: 7.5YR or 10YR
Value: 5 or 6 dry, 4 or 5 moist
Chroma: 4 to 6
Texture: extremely gravelly coarse sand, extremely gravelly loamy coarse sand
Clay content: 0 to 10 percent
Rock fragments: 60 to 80 percent, dominantly gravel
Base saturation: 60 to 100 percent
Reaction: slightly acid or neutral
2C1 horizon:
Hue: 7.5YR or 10YR
Value: 5 or 6 dry, 4 or 5 moist
Chroma: 4 to 6
Texture: very gravelly very coarse sand, very gravelly sand
Clay content: 0 to 8 percent
Rock fragments: 35 to 70 percent, dominantly gravel
Base saturation: 60 to 100 percent
Reaction: slightly acid or neutral
3C2 horizon:
Hue: 7.5YR or 10YR
Value: 5 or 6 dry, 4 or 5 moist
Chroma: 4 to 6
Texture: loamy coarse sand, coarse sand
Clay content: 0 to 10 percent
Rock fragments: 0 to 15 percent
Base saturation: 60 to 100 percent
Reaction: slightly acid or neutral
COMPETING SERIES: There are presently no competing series. When reclassified the following series may be competitors: the
Cosey and
Harpole series.
Cosey and Harpole series average more than 20 percent clay in the control section and less than 15 percent mica (by grain count).
GEOGRAPHIC SETTING:
Parent material: till derived from granitic rocks, gneiss, and schist
Landform: moraines
Slopes: 5 to 35 percent
Elevation: 8,000 to 9,000 feet
Mean annual temperature: 40 to 44 degrees F
Mean annual precipitation: 16 to 22 inches
Precipitation pattern: Wettest months: March, April, and May
Driest months: September and October
Frost-free period: 70 to 100 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are Nanita and Rofork soils. Nanita soils have thin surface layers and are on north facing slopes. Rofork soils have bedrock at depths of less than 20 inches and are in areas where till is a thin mantle over granitic rocks.
DRAINAGE AND PERMEABILITY: Somewhat excessively drained, medium to very high runoff, and moderately rapid permeability.
USE AND VEGETATION: Recreation and wildlife. The present vegetation is moderate to dense stands of ponderosa pine with an understory of mountain muhly, sedges, bluegrass, currant, Parry oatgrass, Griffiths wheatgrass, and needleandthread.
DISTRIBUTION AND EXTENT: Mountains of the north central Rocky Mountains, Colorado; LRR E, MLRA 48A; this series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Larimer County, Colorado, Rocky Mountain National Park soil survey area, 1999. The name is taken from a mountain peak.
REMARKS:
Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon: The zone from 1 to 11 inches (A1 and A2 horizons)
Alfic feature: Mixed E and Bt horizon from 11 to 24 inches. (90 percent E material and 10 percent Bt material).
Argillic horizon: The zone from 11 to 33 inches. (E and Bt and Bt and E horizons)
Particle-size control section: The upper 20 inches of the argillic horizon, from 11 to 31 inches. (E and Bt, and part of the Bt and E horizon)
Lithologic discontinuities: At the upper boundaries of the 2BC and the 3C2 horizons.
Keys to Soil Taxonomy: Series classified according to Eighth Edition, 1998.
ADDITIONAL DATA: