LOCATION ROFORK CO

Established Series
Rev. MRT/TWH
05/2012

ROFORK SERIES

The Rofork series consists of shallow, somewhat excessively drained and well drained soils that formed in slope alluvium and residuum derived from granitic rocks, schist, and gneiss. Rofork soils are on mountain slopes and structural benches. Slopes range from 5 to 70 percent. Mean annual precipitation is about 18 inches and the mean annual temperature is about 42 degrees F.

TAXONOMIC CLASS: Loamy-skeletal, micaceous, frigid, shallow Entic Haplustolls

TYPICAL PEDON: Rofork very gravelly sandy loam, on a east-facing, 8 percent slope in an open stand of ponderosa pine at an elevation of 8,480 feet. (Colors are for dry soil unless otherwise noted.) When described on July 19, 1995 the soil was slightly moist to a depth of 20 inches.

A--0 to 5 inches; very dark grayish brown (10YR 3/2) very gravelly sandy loam, black (10YR 2/1) moist; moderate medium granular structure; soft, very friable, slightly sticky and nonplastic; many very fine and fine roots; 40 percent gravel; neutral (pH 6.8); abrupt smooth boundary. (4 to 8 inches thick)

Bw--5 to 10 inches; dark grayish brown (10YR 4/2) very gravelly sandy loam, very dark brown (10YR 2/2) moist; weak fine subangular blocky and weak fine granular structure; soft, very friable, slightly sticky and nonplastic; many very fine and fine roots; 40 percent gravel; neutral (pH 6.8); abrupt wavy boundary. (4 to 8 inches thick)

C--10 to 14 inches; brown (10YR 5/3) extremely gravelly loamy coarse sand, dark yellowish brown (10YR 4/4) moist; massive; soft, very friable, nonsticky and nonplastic; common very fine roots; 70 percent gravel; neutral (pH 7.0). (0 to 4 inches thick)

Cr--14 to 20 inches; soft to moderately hard, partially decomposed granite.

TYPE LOCATION: Larimer County, Colorado; about 4 miles west of Estes Park, about 2000 feet south and 150 feet east of the northwest corner of sec. 29, T. 5 N., R. 73 W.; Longs Peak USGS topographic quadrangle; lat. 40 degrees 22 minutes 28 seconds N. and long. 105 degrees 36 minutes 24 seconds W.

RANGE IN CHARACTERISTICS:
Soil moisture: ustic moisture regime. The soil moisture control section is usually dry in some part in early summer, moist in some or all parts in late July and August, and intermittently dry in fall; ustic regime, typic subclass.
Mean annual soil temperature: 39 to 45 degrees F.
Mean summer soil temperature: 59 to 63 degrees F.
Depth to paralithic contact: 10 to 20 inches
Thickness of the mollic epipedon: 7 to 16 inches
Lithology of rock fragments: granitic rocks, gneiss, schist

Particle-size control section (weighted average):
Clay content: 7 to 18 percent
Sand content: 55 to 80 percent
Rock fragment content: 35 to 60 percent, dominantly gravel
Mica content: 45 to 70 percent (by grain count)

A Horizon:
Hue: 7.5YR or 10YR
Value: 3 to 5 dry, 2 or 3 moist
Chroma: 1 to 3
Clay content: 7 to 18 percent
Rock fragment content: 35 to 60 percent, dominantly gravel
Reaction: slightly acid or neutral

Bw Horizon (lower part of the A horizon in some pedons):
Hue: 7.5YR or 10YR
Value: 3 to 6 dry, 2 to 4 moist
Chroma: 2 to 4
Clay content: 7 to 18 percent
Texture: very gravelly sandy loam or very gravelly coarse sandy loam, extremely gravelly sandy loam
Rock fragment content: 35 to 75 percent, dominantly gravel
Reaction: slightly acid or neutral

C Horizon (AC or Bw horizon in some pedons):
Hue: 7.5YR or 10YR
Value: 4 to 6 dry, 3 to 5 moist
Chroma: 2 to 6 dry, 2 to 4 moist
Clay content: 5 to 18 percent
Texture: loamy coarse sand, coarse sandy loam, sandy loam, coarse sand; with very gravelly and extremely gravelly modifiers
Rock fragment content: 50 to 85 percent, dominantly gravel
Reaction: slightly acid or neutral

COMPETING SERIES: There are presently no competing series. A soil in a closely related family is the Ratake(CO) series. The Ratake soils have hue of 5YR or redder in the Bw horizon and are in the Typic subgroup.

GEOGRAPHIC SETTING:
Parent material: Slope alluvium and residuum derived from granitic rocks, schist, and gneiss.
Landform: mountain slopes, structural benches
Landform position: summits, shoulders, backslopes
Slopes: 5 to 70 percent
Elevation: 7,500 to 10,000 feet
Mean annual air temperature: 36 to 44 degrees F.
Mean annual precipitation: 14 to 24 inches.
Wettest months: March, April, and May.
Driest months: October and September.
Frost-free period: 50 to 100 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Cathedral, Chasmfalls, and Isolation series. Cathedral soils are lithic and are adjacent to areas of rock outcrop. Chasmfalls soils are moderately deep and are on concave backslopes. Isolation soils are very deep and are on moraines.

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

USE AND VEGETATION: These soils are used for recreation and wildlife habitat. The native plant community is mainly ponderosa pine, mountain muhly, antelope bitterbrush, Parry's oatgrass, and needleandthread.

DISTRIBUTION AND EXTENT: Rocky Mountains of Colorado. LRR E, MLRA 48A. This series is of moderate 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 Rofork is coined from the name of nearby Roaring Fork Creek.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon: The zone from 0 to 10 inches. (A and Bw horizons)
Paralithic contact: The contact with granite at 14 inches. (Cr layer)

Keys to Soil Taxonomy: Series classified according to Eleventh Edition, 2010.

National Cooperative Soil Survey
U.S.A.