LOCATION BUMPHEADS ORTentative Series
TAXONOMIC CLASS: Fine, smectitic, frigid Pachic Argixerolls
TYPICAL PEDON: Bumpheads very stony loam--on an 8 percent slope at an elevation of 5,200 feet--forestland. (Colors are for dry soil unless otherwise noted. The soil was dry throughout when it was described on October 6, 1998.) The soil surface is partially covered with about 15 percent cobbles and 10 percent stones.
A1--0 to 3 inches; dark grayish brown (10YR 4/2) very stony loam, very dark grayish brown (10YR 3/2) moist; strong medium granular structure; soft, very friable, slightly sticky and slightly plastic; many very fine, common fine, and few medium roots; common very fine interstitial pores; 15 percent pebbles, 10 percent cobbles, and 10 percent stones; neutral (pH 6.6); clear smooth boundary. (2 or 3 inches thick)
A2--3 to 12 inches; brown (7.5YR 4/3) cobbly loam, dark brown (7.5YR 3/3) moist; moderate medium subangular blocky structure parting to moderate medium granular; soft, very friable, moderately sticky and slightly plastic; common very fine, common fine, few medium, and few coarse roots; common very fine, common fine, and common medium tubular pores; 15 percent pebbles, 15 percent cobbles, and 4 percent stones; neutral (pH 6.7); clear smooth boundary. (4 to 14 inches thick)
Bt1--12 to 22 inches; brown (7.5YR 5/3) cobbly clay loam, dark brown (7.5YR 3/3) moist; moderate medium subangular blocky structure; slightly hard, friable, moderately sticky and moderately plastic; common very fine, few fine, few medium, and few coarse roots; common very fine and common fine tubular pores; common faint clay films on faces of peds; 10 percent pebbles, 10 percent cobbles, and 4 percent stones; neutral (pH 6.8); clear smooth boundary. (4 to 15 inches thick)
Bt2--22 to 34 inches; brown (7.5YR 5/4) very cobbly clay, brown (7.5YR 4/4) moist; moderate medium angular blocky structure; slightly hard, firm, moderately sticky and moderately plastic; few very fine, few fine, few medium, and few coarse roots; few very fine and few fine tubular pores; common distinct clay films on faces of peds; 15 percent pebbles, 15 percent cobbles, and 5 percent stones; neutral (pH 6.8); clear wavy boundary. (8 to 16 inches thick)
Crt--34 to 38 inches; brown (7.5YR 5/4), weathered basalt, brown (7.5YR 4/4) moist; common faint clay films on pararock fragments. (1 to 8 inches thick)
R--38 inches; hard, unweathered basalt.
TYPE LOCATION: Klamath County, Oregon; about 2 miles southeast of Antler Point, 1.3 miles east of the Main Haul Road, and 0.5 mile east of the cinder pit at the end of the side road; 1,600 feet north and 500 feet east of the southwest corner of section 3, T. 41 S., R. 15 E.; USGS Antler Point 7.5 minute topographic quadrangle; 42 degrees 2 minutes 20 seconds north latitude and 120 degrees 56 minutes 6 seconds west longitude, NAD 27.
RANGE IN CHARACTERISTICS:
Soil moisture - Usually moist in winter and spring, dry in summer and fall; xeric moisture regime that borders on aridic.
Mean annual soil temperature - 45 to 47 degrees F.
Mean summer soil temperature - 59 to 61 degrees F.
Mollic epipedon thickness - 20 to 26 inches, includes the Bt1 horizon.
Argillic horizon thickness - 12 to 24 inches.
Depth to base of argillic horizon - 24 to 40 inches.
Depth to bedrock - 24 to 40 inches to a paralithic contact. The paralithic material below the contact is weathered basalt or tuff. Hard, unweathered bedrock is typically within 60 inches.
Particle-size control section - Clay content: 35 to 50 percent; Rock fragments: 15 to 35 percent, mainly cobbles. Lithology of fragments is basalt.
Reaction - Slightly acid or neutral.
A1 horizon - Value: 4 or 5 dry, 2 or 3 moist.
Chroma: 2 or 3, dry or moist.
Clay content: 20 to 27 percent.
Rock fragments: 35 to 45 percent.
Organic matter content: 2 to 4 percent.
A2 horizon - Hue: 7.5YR or 10YR.
Value: 4 or 5 dry, 2 or 3 moist.
Chroma: 2 through 4 dry, 2 or 3 moist.
Texture: Cobbly loam, cobbly clay loam, or very cobbly clay loam.
Clay content: 24 to 35 percent.
Rock fragments: 20 to 40 percent.
Organic matter content: 2 to 4 percent.
Bt1 horizon - Hue: 7.5YR or 10YR.
Value: 5 or 6 dry.
Chroma: 3 or 4 dry.
Texture: Cobbly clay loam or cobbly clay.
Clay content: 32 to 45 percent.
Rock fragments: 15 to 30 percent.
Organic matter content: 1 to 3 percent.
Bt2 horizon - Hue: 7.5YR or 5YR.
Value: 4 through 6 dry, 3 or 4 moist.
Chroma: 3 or 4, dry or moist.
Texture: Cobbly clay or very cobbly clay.
Clay content: 40 to 50 percent.
Rock fragments: 20 to 35 percent.
COMPETING SERIES: These are the Arcia, Arva, Broadhead, Cristo, Henefer, Rugar, Schnipps (T), and Sweitberg series.
Arcia and Sweitberg soils are moderately deep to lithic contacts. Arva, Rugar, and Schnipps soils are deep to paralithic contacts. Broadhead and Henefer soils are very deep. Cristo soils have limestone rock fragments in the particle-size control section, calcareous C horizons with 1 to 15 percent calcium carbonate equivalent, and paralithic material of shale within the series control section.
GEOGRAPHIC SETTING: Bumpheads soils are on plateaus. They typically occur on summit positions. These soils formed in residuum derived from basalt or tuff. Slopes are 1 to 10 percent. Elevations range from 4,800 to 5,200 feet. The climate is characterized by cold, wet winters and warm, dry summers. The mean annual precipitation is 17 to 20 inches. The mean annual temperature is 43 to 45 degrees F., mean January temperature is 25 to 28 degrees F., and the mean July temperature is 56 to 60 degrees F. The frost-free period is 50 to 80 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Mound and Norcross soils. Mound soils are clayey-skeletal, deep to paralithic contacts, and have argillic horizons and thick mollic epipedons. Norcross soils are clayey, shallow to thin duripans over bedrock, and have mollic epipedons and argillic horizons.
DRAINAGE AND PERMEABILITY: Well drained; high surface runoff; slow permeability.
USE AND VEGETATION: Bumpheads soils are used for livestock grazing, wildlife habitat, and recreation. The native vegetation is a forest canopy of western juniper and ponderosa pine with an understory of Idaho fescue, mountain big sagebrush, and curlleaf mountainmahogany.
DISTRIBUTION AND EXTENT: South-central Oregon. These soils are not extensive. MLRA 21.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California.
SERIES PROPOSED: Klamath County (Gerber Block of Fremont National Forest Area), Oregon 1998. The name is from a pair of prominent buttes in the area.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - The zone from the soil surface to 22 inches (A1, A2, and Bt1 horizons).
Argillic horizon - The zone from 12 to 34 inches (Bt1 and Bt2 horizons).
Paralithic contact - The boundary at 34 inches to underlying soft, weathered bedrock (Crt layer).
Particle-size control section - The zone from 12 to 32 inches (Bt1 horizon and most of the Bt2 horizon).