LOCATION HENSON                  CO

Established Series
Rev. DKR/JPP/TWH
01/2023

HENSON SERIES

The Henson series consist of very deep, well drained soils formed in slope alluvium, alluvium, and colluvium derived from andesite, rhyolite, breccia, or tuff. These soils are on valley fills, mountain slopes, or alluvial fans. Slopes range from 10 to 75 percent. Mean annual precipitation is about 39 inches and the mean annual temperature is about 31 degrees F.

TAXONOMIC CLASS: Loamy-skeletal, isotic Typic Dystrocryepts

TYPICAL PEDON: Henson loam, on a southeast facing 60 percent mountain slope on rangeland at an elevation of 11,840 feet. (Colors are for dry soil unless otherwise noted. When described on August 18, 1992, the soil was moist in the moisture control section.)

A--0 to 2 inches; brown (7.5YR 5/2) loam, dark brown (7.5YR 3/2) moist; weak fine granular structure; soft, friable, nonsticky and nonplastic; 10 percent gravel; strongly acid (pH 5.2); clear smooth boundary. (2 to 15 inches thick)

Bw1--2 to 14 inches; brown (7.5YR 5/4) very cobbly sandy clay loam, dark brown (7.5YR 3/4) moist; moderate fine and medium granular structure; slightly hard, friable, nonsticky and nonplastic; 20 percent gravel, 20 percent cobbles; strongly acid (pH 5.2); gradual wavy boundary.

Bw2--14 to 24 inches; light brown (7.5YR 6/3) very gravelly sandy clay loam, brown (7.5YR 4/3) moist; weak fine granular structure; slightly hard, friable, slightly sticky and slightly plastic; 35 percent gravel, 15 percent cobbles; strongly acid (pH 5.2); gradual wavy boundary. (combined thickness of the Bw horizons is 8 to 26 inches)

C1--24 to 33 inches; brown (7.5YR 5/4) very cobbly sandy clay loam, dark brown (7.5YR 3/4) moist; massive; slightly hard, friable, slightly sticky and slightly plastic; 30 percent gravel, 25 percent cobbles; strongly acid (pH 5.2); clear wavy boundary.

C2--33 to 66 inches; pinkish gray (7.5YR 6/2) extremely cobbly sandy clay loam, dark brown (7.5YR 3/2) moist; massive; slightly hard, friable, slightly sticky and slightly plastic; 40 percent gravel, 30 percent cobbles; strongly acid (pH 5.2). (combined thickness of the C horizons is 24 to 56 inches)

TYPE LOCATION: Hinsdale County, Colorado; about 14 miles southwest of Lake City, Colorado; in an unsectionized area estimated to be in Section 18, T. 43 N., R. 6 W.; USGS Handies Peak topographic quadrangle; latitude 37 degrees, 58 minutes, 55 seconds north and longitude 107 degrees, 33 minutes, 51 seconds west, NAD 1927.

RANGE IN CHARACTERISTICS:
Soil moisture regime: udic; dry in some part of the moisture control section for less than 45 days (cumulative). (Typic udic).
Mean annual soil temperature: 33 to 40 degrees F.
Mean summer soil temperature: 38 to 44 degrees F.
Thickness of ochric epipedon: 2 to 15 inches.
Depth to top of cambic horizon: 2 to 15 inches.

Particle-size control section:
Clay content: 18 to 35 percent
Rock fragment content: 35 to 75 percent

A horizon:
Hue: 5YR to 10YR
Value: 5 or 6 dry, 3 to 5 moist
Chroma: 2 to 4 dry or moist
Texture: L, GRV-L, FSL
Rock fragments: andesite, rhyolite, breccia, or tuff. 5 to 40 percent total rock fragments; 5 to 40 percent gravel, 0 to 10 percent cobbles, 0 to 5 percent stones.
Base saturation: 35 to 45 percent.
Reaction: very strongly acid (pH 4.5) or strongly acid (pH 5.5)

Bw horizons:
Hue: 5YR or 7.5YR
Value: 5 to 7 dry, 3 to 6 moist
Chroma: 2 to 6 dry or moist
Texture: CBV-SCL, GRV-SCL, CBV-L, GRV-L, CBV-CL, CBX-SCL, CBX-CL, GRX-SCL, STV-SCL
Rock fragments: andesite, rhyolite, breccia, or tuff. 35 to 75 percent total rock fragments; 10 to 50 percent gravel, 15 to 60 percent cobbles, 0 to 15 percent stones.
Base saturation: 35 to 45 percent
Reaction: very strongly acid (pH 4.5) to strongly acid (pH 5.5)

C horizons:
Hue: 5YR or 7.5YR
Value: 5 to 7 dry, 3 to 6 moist
Chroma: 2 to 6 dry or moist
Texture: CBV-SCL, CBX-SCL, CBX-L, CBX-SL, STX-SL, STX-L
Rock fragments: andesite, rhyolite, breccia, or tuff. 35 to 75 percent total rock fragments; 15 to 40 percent gravel, 25 to 50 percent cobbles, 0 to 15 percent stones.
Base saturation: 35 to 50 percent.
Reaction: very strongly acid (pH 4.5) to strongly acid (pH 5.5)

COMPETING SERIES: These are the Bensley, Endlich, and Fallriver series.

In addition, the following series may be competitors when reclassified: Jeru, Klutch, Oatman, and Snotown series.

Bensley and Jeru soils: have hue yellower than 7.5YR in the particle-size control section.
Endlich, Klutch, and Snotown soils: have a lithic contact at 20 to 40 inches.
Fallriver soils: have less than 18 percent clay in the particle-size control section.
Oatman soils have mean annual soil temperature greater than 40 degrees F. and mean summer soil temperature greater than of 44 degrees F.

GEOGRAPHIC SETTING:
Parent material: slope alluvium, alluvium, and colluvium derived from andesite, rhyolite, breccia, or tuff.
Landform: valley fills, mountain slopes, and alluvial fans. Slopes: 10 to 75 percent.
Elevation: 10,600 to 13,500 feet.
The mean annual air temperature: 27 to 34 degrees F.
and the mean summer temperature is 43 to 50 degrees F.
The mean annual precipitation is 30 to 46 inches. The frost-free period is 25 to 50 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Moran, Telluride, and Whitecross soils. Moran soils are on toeslopes and valley fills and have an umbric epipedon. Telluride and Whitecross soils are on backslopes and have a lithic contact at 10 to 20 inches.

DRAINAGE AND PERMEABILITY: Well drained; medium to very high runoff; moderate permeability.

USE AND VEGETATION: This soil is used for summer range for sheep, recreation, and wildlife habitat. The native vegetation is mostly Ross' avens, alpine bluegrass, alpine fescue, kobresia, American bistort, tufted hairgrass, and Baker's wheatgrass. The soils with a south aspect at lower elevations also have Thurber's fescue.

DISTRIBUTION AND EXTENT: Alpine areas of southwest Colorado in LRR E and MLRA 48A. The series is of moderate extent.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana

SERIES ESTABLISHED: Ouray Soil Survey Area, Hinsdale County, Colorado, 1998.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon: the zone from 0 to 2 inches. (A horizon)
Cambic horizon: the zone from 2 to 24 inches. (Bw horizons)
Particle-size control section: the zone from 10 to 40 inches (part of the Bw1, the Bw2, C1, and part of the C2 horizon)

This pedon was classified in accordance with Keys to Soil Taxonomy, 8th Edition, 1998.

A former revision moved the typical pedon to a different location in the Ouray Soil Survey Area.

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National Cooperative Soil Survey
U.S.A.