LOCATION GREGGO OREstablished Series
TAXONOMIC CLASS: Loamy-skeletal, magnesic, mesic Lithic Eutrudepts
TYPICAL PEDON: Greggo very cobbly clay loam, woodland on a 50 percent southeast-facing slope at an elevation of 1,920 feet. (When described on September 30, 1988, the soil profile was dry throughout. Colors are for moist soil unless otherwise noted.)
A--0 to 4 inches; dark reddish brown (5YR 3/3) very cobbly clay loam, brown (7.5YR 5/4) dry; moderate very fine subangular blocky structure; slightly hard, firm, slightly sticky and slightly plastic; many very fine and fine roots; many fine tubular pores; 30 percent gravel and 20 percent cobbles; slightly acid (pH 6.4); clear smooth boundary. (3 to 5 inches thick)
Bw1--4 to 12 inches; reddish brown (5YR 4/4) extremely gravelly clay loam, brown (7.5YR 5/4) dry; moderate fine and medium subangular blocky structure; slightly hard, firm, slightly sticky and slightly plastic; many very fine and fine roots; many fine tubular pores; 50 percent gravel and 20 percent cobbles; slightly acid (pH 6.4); gradual wavy boundary.
Bw2--12 to 17 inches; reddish brown (5YR 4/4) extremely gravelly clay loam, light brown (7.5YR 6/4) dry; moderate fine and medium subangular blocky structure; hard, firm, moderately sticky and moderately plastic; common very fine and fine roots; many fine tubular pores; 55 percent gravel and 25 percent cobbles; neutral (pH 6.6); abrupt wavy boundary. (Combined thickness of the Bw horizon ranges from 7 to 15 inches.)
R--17 inches; highly fractured peridotite.
TYPE LOCATION: Curry County, Oregon; located about 1,700 feet north and 1,025 feet east of the southwest corner of section 18, T. 375., R. 13 W., W.M. (Latitude 42 degrees, 22 minutes, 20 seconds N; Longitude 124 degrees, 17 minutes, 43 seconds W.)
RANGE IN CHARACTERISTICS: The mean annual soil temperature is 47 to 54 degrees F. The soils are usually moist and are dry for less than 45 consecutive days in all parts between depths of 4 and 12 inches in the four months following the summer solstice. The particle-size control section averages 30 to 35 percent clay and 50 to 80 percent rock fragments. Depth to bedrock and solum thickness is 10 to 20 inches. The solum is slightly acid or neutral throughout. Hue is 5YR or 7.5YR.
The A horizon has value of 3 or 4 moist, 5 or 6 dry and chroma of 3 or 4 moist and dry. It is very cobbly clay loam with 27 to 30 percent clay. It has 30 to 35 percent gravel and 20 to 25 percent cobbles.
The Bw horizon has value of 4 or 5 moist, 5 to 7 dry and chroma of 4 to 6 moist and dry. It is very gravelly clay loam, extremely gravelly clay loam, or extremely cobbly clay loam with 30 to 35 percent clay. It has 40 to 60 percent gravel and 20 to 30 percent cobbles.
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Greggo soils are on metastable broad ridgetops and active side slopes of mountains. Slopes are 0 to 90 percent. The soils formed in colluvium and residuum derived from serpentinized peridotite and other serpentinized rock types. Elevations are 400 to 3,000 feet. The climate is characterized by warm wet winters and hot moist summers. The mean annual precipitation is 90 to 130 inches. The mean annual temperature is 45 to 53 degrees F. The frost-free period is about 120 to 210 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Mislatnah, Redflat, and Serpentano soils. Mislatnah, Redflat, and Serpentano soils occur on broad ridgetops and side slopes of mountains. Mislatnah soils are 20 to 40 inches deep to bedrock and are loamy-skeletal. Redflat soils are over 60 inches deep to bedrock and are fine-loamy. Serpentano soils are loamy-skeletal and are 40 to 60 inches to bedrock.
DRAINAGE AND PERMEABILITY: Well drained; moderate permeability.
USE AND VEGETATION: These soils are used mainly for watershed, recreation, woodland, and wildlife habitat. The native vegetation is knobcone pine, Jeffrey pine, tanoak, incense cedar, western white pine, Douglas fir, sugar pine, tanoak, California laurel, whiteleaf manzanita, huckleberry oak, squawcarpet, common beargrass, pinemat manzanita, and grasses.
DISTRIBUTION AND EXTENT: Mountainous areas of southwestern Oregon MLRA 1. The series is not extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Curry County, Oregon, 1995.
REMARKS: Diagnostic horizons and features recognized in this pedon include:
Ochric epipedon
Cambic horizon - from 4 to 17 inches (Bw1 and Bw2 horizons).
Lithic subgroup - bedrock at 17 inches (R horizon).
Eutrochrepts feature - base saturation by ammonium acetate is assumed to be 60 percent or more in some subhorizon within 20 inches. This is based on laboratory data from the associated Redflat soil.
Particle-size control section - from 10 to 17 inches (lower part of Bw1 and the Bw2 horizons)
Also qualifies as Dystric subgroup.