LOCATION GROHS ORTentative Series
TAXONOMIC CLASS: Fine, smectitic, mesic Pachic Argixerolls
TYPICAL PEDON: Grohs cobbly loam--on a 6 percent slope at an elevation of 4,880 feet--forestland. (Colors are for dry soil unless otherwise noted. The soil was dry to 14 inches and slightly moist below 14 inches, when it was described on September 23, 1998.) The soil surface is covered by a one inch layer of undecomposed or slightly decomposed pine needles and twigs.
A1--0 to 2 inches; brown (7.5YR 4/3) cobbly loam, dark brown (7.5YR 3/3) moist; moderate medium subangular blocky structure parting to moderate medium and coarse granular; slightly hard, very friable, slightly sticky and slightly plastic; many very fine and common fine roots; many very fine interstitial and common very fine tubular pores; 5 percent pebbles, 15 percent cobbles, and 5 percent stones; neutral (pH 6.8); abrupt smooth boundary. (2 to 4 inches thick)
A2--2 to 5 inches; dark brown (7.5YR 3/4) cobbly loam, dark brown (7.5YR 3/2) moist; moderate coarse subangular blocky structure parting to moderate medium granular; soft, very friable, slightly sticky and slightly plastic; many very fine, common fine, and few medium roots; common very fine and common fine tubular pores; 5 percent pebbles, 10 percent cobbles, and 10 percent stones; neutral (pH 6.8); abrupt smooth boundary. (3 to 10 inches thick)
Bt1--5 to 9 inches; dark brown (7.5YR 3/4) cobbly clay loam, dark brown (7.5YR 3/2) moist; moderate medium and coarse subangular blocky structure; slightly hard, very friable, moderately sticky and moderately plastic; common very fine, common fine, common medium, and few coarse roots; common very fine and common fine tubular pores; few faint clay films on faces of peds; 10 percent pebbles and 10 percent cobbles; neutral (pH 6.8); clear smooth boundary. (4 to 8 inches thick)
Bt2--9 to 14 inches; dark brown (7.5YR 3/4) gravelly clay, dark brown (7.5YR 3/2) moist; moderate medium and coarse angular blocky structure; hard, firm, very sticky and moderately plastic; common very fine, common fine, many medium, many coarse, and many very coarse roots; common very fine and few fine tubular pores; common distinct clay films on faces of peds; 10 percent pebbles and 5 percent cobbles; neutral (pH 6.8); clear smooth boundary. (4 to 14 inches thick)
Bt3--14 to 23 inches; brown (7.5YR 4/3) gravelly clay, dark brown (7.5YR 3/3) moist; moderate medium angular blocky structure; hard, firm, very sticky and moderately plastic; common fine, common medium, many coarse, and common very coarse roots; common very fine, common fine, and few medium tubular pores; common distinct clay films on faces of peds; 20 percent pebbles; neutral (pH 6.6); abrupt wavy boundary. (4 to 18 inches thick)
Cr--23 to 25 inches; weathered basalt. (2 to 8 inches thick)
R--25 inches; hard, unweathered basalt.
TYPE LOCATION: Klamath County, Oregon; about 2 miles south of Brady Butte, 50 feet south of the State Line Road, and 200 feet east of the telephone repeater road; 400 feet north and 1,500 feet west of the southeast corner of section 23, T. 41 S., R. 14.5 E.; USGS Sagebrush Butte 7.5 minute topographic quadrangle; 41 degrees 59 minutes 40 seconds north latitude and 121 degrees 1 minute 22 seconds west longitude, NAD 27.
RANGE IN CHARACTERISTICS:
Soil moisture - Usually moist in winter and spring and dry in summer and fall; xeric moisture regime that borders on aridic.
Mean annual soil temperature - 47 to 49 degrees F.
Mean summer soil temperature - 60 to 62 degrees F.
Mollic epipedon thickness - 20 to 28 inches, includes all subdivisions of the argillic horizon, except for the Bt3 horizon in some pedons.
Argillic horizon thickness - 14 to 28 inches.
Depth to base of the argillic horizon - 20 to 36 inches.
Depth to bedrock - 20 to 36 inches to a paralithic contact. The paralithic material below the contact is weathered basalt. Hard, unweathered basalt bedrock is typically within 40 inches.
Particle-size control section - Clay content: 35 to 50 percent; Rock fragments: 15 to 35 percent, mainly pebbles and cobbles. Lithology of fragments is basalt.
Reaction - Neutral or slightly alkaline.
A1 horizon - Hue: 10YR or 7.5 YR.
Value: 4 or 5 dry, 2 or 3 moist.
Chroma: 2 or 3, dry or moist.
Clay content: 16 to 24 percent.
Rock fragments: 15 to 35 percent.
Organic matter content: 2 to 4 percent.
A2 horizon - Hue 10YR or 7.5YR.
Value: 3 or 5 dry, 2 or 3 moist.
Chroma: 2 through 4 dry, 2 or 3 moist.
Textures: Cobbly loam or very cobbly loam.
Clay content: 20 to 27 percent.
Rock fragments: 20 to 40 percent.
Organic matter content: 2 to 4 percent.
Bt1 horizon - Value: 3 through 5 dry, 2 or 3 moist.
Chroma: 2 through 4 dry, 2 or 3 moist.
Textures: Cobbly clay loam or very cobbly clay loam.
Clay content: 30 to 40 percent.
Rock fragments: 15 to 40 percent.
Organic matter content: 1 to 3 percent.
Bt2 horizon - Value: 3 through 5 dry, 3 or 4 moist.
Chroma: 3 or 4 dry, 2 or 3 moist.
Textures: Gravelly clay loam, gravelly clay, or very cobbly clay.
Clay content: 35 to 45 percent.
Rock fragments: 15 to 40 percent.
Organic matter content: 1 to 3 percent.
Bt3 horizon - Value: 4 through 6 dry, 3 or 4 moist.
Chroma: 3 or 4, dry or moist.
Textures: Gravelly clay or cobbly clay.
Clay content: 40 to 55 percent.
Rock fragments: 20 to 35 percent.
Organic matter content: 0.5 to 2 percent.
COMPETING SERIES: These are the Adaboi (T), Denbar, Deshler, Deter, Deterson, Esperanza, Jacknife, Medford, Mindego, Nebeker, and Patburn series. Adaboi, Deter, Deterson, Jacknife, Medford, Nebeker, and Patburn soils are very deep. Deshler soils have less than 15 percent rock fragments in the particle-size control section and have paralithic material of siltstone or consolidated lacustrine deposits. Denbar and Esperanza soils are deep to duripans. Mindego soils are deep to lithic contacts.
GEOGRAPHIC SETTING: Grohs soils are on hills. They occur in plateau landscapes. These soils formed in loess and residuum derived from basalt and tuff. Slopes are 2 to 20 percent. Elevations range from 4,700 to 5,200 feet. The climate is characterized by cold, wet winters and warm, dry summers. The mean annual precipitation is 16 to 18 inches. The mean annual temperature is 45 to 47 degrees F., mean January temperature is 27 to 30 degrees F., and the mean July temperature is 58 to 62 degrees F. The frost-free period is 60 to 90 days.
GEOGRAPHICALLY ASSOCIATED SOILS: This is the Carrbutte soil. Carrbutte soils are clayey-skeletal, deep to paralithic contacts, and have thick mollic epipedons and argillic horizons.
DRAINAGE AND PERMEABILITY: Well drained; high surface runoff; slow permeability.
USE AND VEGETATION: Grohs soils are used for livestock grazing, wood production, wildlife habitat, and recreation. The native vegetation is a forest canopy of western juniper and ponderosa pine with an understory of Idaho fescue, bluebunch wheatgrass, mountain big sagebrush, and curlleaf mountainmahogany.
DISTRIBUTION AND EXTENT: Southcentral 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 an old ranch in the area.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - The zone from the soil surface to 23 inches (A1, A2, Bt1, Bt2, and Bt3 horizons).
Argillic horizon - The zone from 5 to 23 inches (Bt1, Bt2, and Bt3 horizons).
Paralithic contact - The boundary at 23 inches to underlying soft, weathered bedrock (Cr layer).
Particle-size control section - The zone from 5 to 23 inches (Bt1, Bt2, and Bt3 horizons).