LOCATION NORCROSS OREstablished Series
TAXONOMIC CLASS: Clayey, smectitic, frigid, shallow Vitrandic Durixerolls
TYPICAL PEDON: Norcross very cobbly ashy loam--on a 1 percent slope at an elevation of 4,950 feet--rangeland. (Colors are for dry soil unless otherwise noted. The soil was dry throughout when it was described on November 5, 1997.)
A1--0 to 3 inches; light brown (7.5YR 6/3) very cobbly ashy loam, dark brown (7.5YR 3/3) moist; weak thick platy structure parting to moderate thin platy; hard, friable, slightly sticky and slightly plastic; many very fine and few fine roots; common fine and common medium vesicular pores; 15 percent pebbles, 20 percent cobbles, and 5 percent stones; neutral (pH 7.2); abrupt smooth boundary. (2 or 3 inches thick)
A2--3 to 6 inches; brown (7.5YR 5/3) cobbly ashy loam, dark brown (7.5YR 3/3) moist; weak thin platy structure parting to moderate medium granular; soft, very friable, slightly sticky and slightly plastic; common very fine, common fine, and few medium roots; common fine and common medium tubular pores; 15 percent pebbles and 12 percent cobbles; neutral (pH 7.2); clear smooth boundary. (0 to 5 inches thick)
Bt1--6 to 10 inches; brown (7.5YR 5/3) cobbly ashy clay loam, dark brown (7.5YR 3/4) moist; moderate medium subangular blocky structure parting to weak fine angular blocky; slightly hard, firm, moderately sticky and moderately plastic; common very fine, few fine, and few medium roots; common fine and common medium tubular pores; common faint clay films on faces of peds; 5 percent pebbles and 15 percent cobbles; slightly alkaline (pH 7.4); abrupt smooth boundary. (3 to 8 inches thick)
Bt2--10 to 18 inches; brown (7.5YR 5/4) clay, dark brown (7.5YR 3/4) moist; strong medium prismatic structure parting to strong medium angular blocky; very hard, very firm, moderately sticky and very plastic; few very fine and few fine roots; few fine tubular pores; few pressure faces; common distinct clay films on faces of peds; slightly alkaline (pH 7.5); clear smooth boundary. (3 to 10 inches thick)
Bt3--18 to 20 inches; light brown (7.5YR 6/3) clay, brown (7.5YR 4/4) moist; moderate medium prismatic structure parting to moderate medium and strong fine angular blocky; hard, firm, moderately sticky and very plastic; few very fine and few fine roots; few very fine and few fine tubular pores; common pressure faces; common distinct and few faint clay films on faces of peds; slightly alkaline (pH 7.6); abrupt smooth boundary. (0 to 7 inches thick)
Bqm--20 to 31 inches; pink (7.5YR 7/4) cemented material, strong brown (7.5YR 4/6) moist; strong thick platy structure; very rigid; indurated by secondary silica; widely spaced fractures in the upper inch; thin laminar caps of opal on top of peds; slightly alkaline (pH 7.8); abrupt wavy boundary. (2 to 26 inches thick)
R--31 inches; hard vesicular basalt.
TYPE LOCATION: Klamath County, Oregon; about 0.25 mile west of the CCC road on the access road to the Barnes Valley Creek boat launch, 75 feet north of the road and close to the range trend plot stake; approximately 1,000 feet north and 150 feet west of the southeast corner of section 21, T. 39 S., R. 14 E.; USGS Gerber Reservoir 7.5 minute topographic quadrangle; 42 degrees 10 minutes 6 seconds north latitude and 121 degrees 3 minutes 23 seconds west longitude, NAD27.
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 - 7 to 15 inches; includes the Bt1 horizon, and in some pedons also includes the Bt2 horizon, when the upper 7 inches of soil is mixed.
Argillic horizon thickness - 7 to 16 inches.
Depth to base of argillic horizon - 12 to 20 inches.
Depth to duripan - 12 to 20 inches.
Duripan thickness - 2 to 26 inches.
Depth to bedrock - 18 to 46 inches to a lithic contact.
Particle-size control section - Clay content: 45 to 55 percent;
Rock fragments: 0 to 10 percent, mainly pebbles and cobbles. Lithology of fragments is dominantly basalt.
Vitrandic intergrade properties - Occurs in horizons from the soil surface to at least 7 inches in depth within horizons having clay content of less than about 40 percent.
Reaction - Neutral or slightly alkaline.
Other features - Some pedons have Btq horizons.
A1 horizon
Hue: 10YR or 7.5YR.
Value: 4 through 6 dry, 2 or 3 moist; A dry value of 6 is only in thin subhorizons in some pedons and the upper 7 inches when mixed has a dry value of 5.
Chroma: 2 or 3, dry or moist.
Texture: Very cobbly ashy loam, very cobbly ashy fine sandy loam, cobbly ashy loam, gravelly ashy loam, cobbly ashy fine sandy loam, or extremely cobbly ashy loam.
Clay content: 18 to 27 percent.
Rock fragments: 15 to 65 percent.
Organic matter content: 2 to 4 percent.
Volcanic glass content: 15 to 30 percent in coarse silt through fine sand fractions.
Oxalate extractable aluminum plus one-half oxalate iron: 0.2 to 0.4 percent.
A2 horizon (when present)
Hue: 10YR or 7.5YR.
Value: 5 or 6 dry, 2 or 3 moist; A dry value of 6 is only in thin subhorizons in some pedons and the upper 7 inches when mixed has a dry value of 5.
Chroma: 2 or 3, dry or moist.
Texture: Cobbly ashy loam, cobbly ashy clay loam, very cobbly ashy loam, or very cobbly ashy clay loam.
Clay content: 22 to 36 percent.
Rock fragments: 20 to 40 percent.
Organic matter content: 2 to 4 percent.
Volcanic glass content: 15 to 30 percent in coarse silt through fine sand fractions.
Oxalate extractable aluminum plus one-half oxalate iron: 0.2 to 0.4 percent.
Bt1 horizon
Hue: 10YR or 7.5YR.
Value: 5 or 6 dry, 3 or 4 moist.
Chroma: 2 through 4, dry or moist.
Texture: Ashy clay loam, cobbly ashy clay loam, clay, or cobbly clay.
Clay content: 36 to 46 percent.
Rock fragments: 0 to 25 percent.
Organic matter content: 1 to 3 percent.
Volcanic glass content: 10 to 25 percent in coarse silt through fine sand fractions.
Oxalate extractable aluminum plus one-half oxalate iron: 0.2 to 0.4 percent.
Bt2 horizon
Value: 5 or 6 dry, 3 or 4 moist.
Chroma: 3 or 4, dry or moist.
Texture: Clay or cobbly clay.
Clay content: 40 to 55 percent.
Rock fragments: 0 to 25 percent.
Organic matter content: 1 to 3 percent.
Other features: Some pedons have texture of ashy clay loam in thin subhorizons.
Bt3 horizon (when present)
Value: 5 through 7 dry, 3 or 4 moist.
Chroma: 3 through 6, dry or moist.
Clay content: 45 to 60 percent.
Rock fragments: 0 to 10 percent, mainly cobbles.
Bqm horizon
Value: 7 or 8 dry, 4 through 6 moist.
Chroma: 3 through 6, dry or moist.
Cementation: Indurated or very strongly cemented.
COMPETING SERIES: This is the Dunres series. Dunres soils average 35 to 45 clay in the particle-size control section and have 60 to 80 percent volcanic glass in the mollic epipedon.
GEOGRAPHIC SETTING: Norcross soils are on lava plateaus. They typically occur on summit positions. These soils formed in volcanic ash over residuum derived from basalt. Slopes are 0 to 10 percent. Elevations range from 4,800 to 5,400 feet. The climate is subhumid and characterized by cold, moist winters and warm, dry summers. The mean annual precipitation is 14 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 Casebeer, Devaul, Dranket, and Mound soils.
DRAINAGE AND PERMEABILITY: Well drained; very high surface runoff; slow permeability (moderately low or moderately high saturated hydraulic conductivity).
USE AND VEGETATION: Norcross soils are used for livestock grazing, wildlife habitat, and recreation. The native vegetation is Idaho fescue, Sandberg's bluegrass, bluebunch wheatgrass, low sagebrush, and western juniper.
DISTRIBUTION AND EXTENT: South-central Oregon. These soils are moderately extensive. MLRA 21.
MLRA OFFICE RESPONSIBLE: Reno, Nevada.
SERIES ESTABLISHED: Lake County (Northern Part), Oregon, 2006. The series was proposed as part of the Gerber Block of the Fremont National Forest Area, Klamath County, Oregon in 1998. The name is from a spring in the Fremont NF survey area.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - The zone from the soil surface to 7 inches (A1 and A2 horizons and part of the Bt1 horizon).
Argillic horizon - The zone from 6 to 20 inches (Bt1, Bt2, and Bt3 horizons).
Vitrandic intergrade feature - The zone from the soil surface to 10 inches (A1, A2, and Bt1 horizons).
Duripan- The zone from 20 to 31 inches (Bqm horizon).
Lithic contact - The boundary at 31 inches to underlying hard bedrock (R layer).
Particle-size control section - The zone from 6 to 20 inches (Bt1, Bt2, and Bt3 horizons).
ADDITIONAL DATA: Volcanic glass content determined locally by optical grain counts using a polarizing petrographic microscope. The typical pedon for the series from the Gerber Block of the Fremont National Area and one pedon from Lake County, Oregon, Northern Part were sampled and glass was counted in upper horizons. Oxalate extractable aluminum plus one-half oxalate extractable iron values are estimated.