LOCATION CHASMFALLS              CO

Established Series
LAN/AWS/TWH
05/2012

CHASMFALLS SERIES

The Chasmfalls series consists of moderately deep, somewhat excessively drained soils that formed in slope alluvium and residuum derived from granitic rocks, schist and gneiss. Chasmfalls soils are on mountain slopes and pediments. Slopes range from 1 to 25 percent. Mean annual precipitation is about 18 inches and the mean annual temperature is about 42 degrees F.

TAXONOMIC CLASS: Coarse-loamy, micaceous, frigid Pachic Haplustolls

TYPICAL PEDON: Chasmfalls gravelly sandy loam, on a northeast facing, concave, 10 percent slope on grassland and open ponderosa pine at an elevation of 8,560 feet. (Colors are for dry soil unless otherwise noted.) When described on July 19, 1995 the soil was moist throughout.

A1--0 to 4 inches; very dark gray (10YR 3/1) gravelly sandy loam, black (10YR 2/1) moist; moderate very fine granular structure; soft, very friable, nonsticky and nonplastic; many very fine and fine roots; 15 percent gravel; slightly acid (pH 6.2); abrupt wavy boundary. (3 to 7 inches thick)

A2--4 to 13 inches; very dark grayish brown (10YR 3/2) gravelly coarse sandy loam, very dark brown (10YR 2/2) moist; weak fine granular structure; soft, very friable, nonsticky and nonplastic; common very fine and fine roots; 30 percent gravel; slightly acid (pH 6.2); clear smooth boundary. (7 to 13 inches thick)

Bw--13 to 19 inches; dark grayish brown (10YR 4/2) gravelly sandy loam, very dark brown (10YR 2/2) moist; weak medium subangular blocky structure; slightly hard, very friable, nonsticky and nonplastic; common very fine and fine roots; 30 percent gravel; neutral (pH 6.8); clear smooth boundary. (5 to 10 inches thick)

BC--19 to 28 inches; dark grayish brown (10YR 4/2) gravelly sandy loam, very dark grayish brown (10YR 3/2) moist; massive; loose, nonsticky and nonplastic; few very fine and fine roots; 20 percent gravel; neutral (pH 7.0); abrupt wavy boundary. (5 to 10 inches thick)

Cr--28 to 38 inches; soft partially decomposed granite.

TYPE LOCATION: Larimer County, Colorado; about 0.8 miles south of Deer Ridge; located about 1,300 feet south and 400 feet west of the northeast corner of sec. 30, T. 5 N., R. 73 W.; Estes Park USGS quad; lat. 40 degrees 22 minutes 34 seconds N. and long. 105 degrees 36 minutes 31 seconds W., NAD 1927

RANGE IN CHARACTERISTICS:
Soil moisture regime: ustic moisture regime
Mean annual soil temperature: 40 to 46 degrees F
Mean summer soil temperature: 59 to 63 degrees F
Depth to paralithic contact: 20 to 40 inches to granite, schist, and gneiss
Thickness of the mollic epipedon: 16 to 40 inches

Particle-size control section (weighted average):
Clay content: 8 to 18 percent
Sand content: 50 to 80 percent
Rock fragments: 20 to 35 percent gravel
Mica content: 40 to 70 percent (by grain count)

A horizons:
Hue: 7.5YR or 10YR
Value: 2.5 or 4 dry, 2 or 3 moist
Chroma: 1 to 3
Texture: gravelly sandy loam or gravelly coarse sandy loam
Clay content: 8 to 18 percent
Sand content: 45 to 70 percent
Rock fragments: 15 to 35 percent
Reaction: Moderately acid to neutral

Bw horizon:
Hue: 7.5YR or 10YR
Value: 3 to 5 dry, 2 or 3 moist
Chroma: 2 to 4 dry, 1 to 3 moist
Texture: gravelly sandy loam, gravelly coarse sandy loam, coarse sandy loam
Clay content: 8 to 18 percent
Sand content: 55 to 80 percent
Rock fragments: 10 to 35 percent
Reaction: Slightly acid or neutral

BC horizon (lower part of the Bw in some pedons):
Hue: 7.5YR or 10YR
Value: 3 to 5 dry, 2 to 4 moist
Chroma: 2 to 4
Texture: gravelly sandy loam, gravelly coarse sandy loam
Clay content: 8 to 16 percent
Sand content: 60 to 75 percent
Rock fragments: 15 to 35 percent
Reaction: Slightly acid to slightly alkaline

COMPETING SERIES: There are currently no other series in this family. A closely related soil is the Coberly series. Coberly soils have rock fragments derived from sandstone and have less than 15 percent mica.

GEOGRAPHIC SETTING:
Parent material: Slope alluvium and residuum derived from granitic rocks, gneiss, and schist
Landform: Mountain slopes and pediments
Slopes: 1 to 25 percent
Elevation: 7,500 to 9,000 feet
Mean annual temperature: 40 to 44 degrees F
Mean annual precipitation: 14 to 22 inches
Precipitation pattern: Wettest months; March-May; Driest months; September-October
Frost-free period: 70 to 105 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Cathedral, Lumpyridge, Ratake, and Rofork series.
Cathedral soils occur above or on the same landform and are shallow
Lumpyridge soils occur below or on the same landform and are very deep
Ratake soils occur above or on the same landform and are shallow
Rofork soils occur above or on the same landform and are shallow

DRAINAGE AND PERMEABILITY: Somewhat excessively drained, rapid to very rapid runoff, moderately rapid permeability.

USE AND VEGETATION: These soils are used for recreation and wildlife habitat. Native vegetation is ponderosa pine, mountain muhly, needleandthread, Parry oatgrass, Griffiths wheatgrass, and antelope bitterbrush.

DISTRIBUTION AND EXTENT: Mountains of northcentral 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, 1999. Rocky Mountain National Park soil survey area. The name is taken from a geographical feature in the area.

REMARKS:
Diagnostic horizons and features recognized in this pedon are:
Particle-size control section: The zone from 10 to 28 inches. (A2, Bw, and BC horizons)
Mollic epipedon: The zone from 0 to 28 inches. (A1, A2, Bw, and BC horizons)
Paralithic contact: The contact with granite at 28 inches. (Cr layer)

Keys to Soil Taxonomy: Series classified according to Eighth Edition, 1998.

ADDITIONAL DATA:

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National Cooperative Soil Survey
U.S.A.