LOCATION GRAVECREEK OREstablished Series
TAXONOMIC CLASS: Loamy-skeletal, magnesic, mesic Typic Dystroxerepts
TYPICAL PEDON: Gravecreek gravelly loam, forested. (Colors are for moist soil unless otherwise noted.)
Oi--1 inch to 0; partially decomposed needles, leaves, and twigs.
A1--0 to 3 inches; very dark grayish brown (10YR 3/2) gravelly loam, brown (10YR 5/3) dry; strong fine granular structure; slightly hard, friable, slightly sticky and slightly plastic; many very fine and common fine and medium roots; many very fine irregular pores; 25 percent gravel and 5 percent cobbles; moderately acid (pH 5.8); abrupt smooth boundary. (2 to 5 inches thick)
A2--3 to 7 inches; dark brown (10YR 3/3) gravelly loam, light yellowish brown (10YR 6/4) dry; strong fine granular structure; slightly hard, friable, slightly sticky and slightly plastic; many very fine, common fine and medium, and few coarse roots; many very fine irregular pores; 25 percent gravel and 5 percent cobbles; strongly acid (pH 5.4); clear wavy boundary. (0 to 4 inches thick)
Bw1--7 to 15 inches; brown (10YR 4/3) very gravelly clay loam, light yellowish brown (10YR 6/4) dry; moderate fine subangular blocky structure; slightly hard, friable, sticky and plastic; common very fine and few fine, medium, and coarse roots; common very fine tubular pores; 30 percent gravel and 15 percent cobbles; strongly acid (pH 5.4); clear wavy boundary. (5 to 13 inches thick)
Bw2--15 to 29 inches; light olive brown (2.5Y 5/4) very cobbly clay loam, very pale brown (10YR 7/4) dry; moderate fine and medium angular blocky structure; hard, friable, sticky and plastic; common very fine and few fine and medium roots; common very fine tubular pores; 30 percent gravel and 20 percent cobbles; strongly acid (pH 5.2); abrupt wavy boundary. (8 to 18 inches thick)
R--29 inches; fractured serpentinite.
TYPE LOCATION: Jackson County, Oregon; approximately 1,700 feet west and 2,300 feet north of the southeast corner of sec. 33, T. 33 S., R. 4 W., W.M.
RANGE IN CHARACTERISTICS: These soils are usually moist but are dry in the moisture control section for 45 to 60 consecutive days in the four months that follow the summer solstice. The mean annual soil temperature ranges from 47 to 54 degrees F. Depth to bedrock ranges from 20 to 40 inches. The particle-size control section averages 27 to 35 percent clay, 25 to 40 percent gravel, and 10 to 20 percent cobbles. It is strongly acid to neutral.
The A horizon has hue of 10YR or 7.5YR, value of 2 through 4 moist, 4 through 6 dry, and chroma of 1 through 4 moist and 2 through 4 dry. Dry value of 4 or 5 only occur in the upper part of the A horizon. It has 10 to 25 percent gravel, 5 to 25 percent cobbles, and 0 to 5 percent stones. It is a gravelly loam, cobbly loam, or very cobbly loam.
The Bw horizon has hue of 7.5YR, 10YR, or 2.5Y, value of 3 through 5 moist, 5 through 7 dry, and chroma of 2 or 4 moist and dry. It has 25 to 40 percent gravel, 10 to 20 percent cobbles, and 0 to 5 percent stones. It is a very cobbly clay loam or very gravelly clay loam.
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Gravecreek soils are on ridges and hill slopes at elevations of 600 to 5,000 feet. These soils formed in colluvium derived from serpentinized rock. The mean annual precipitation is typically 40 to 60 inches. In the interior mountains of Curry County, Oregon, the mean annual precipitation may range to 100 inches. The mean annual temperature is 45 to 52 degrees F. The frost-free period is 100 to 160 days. Slopes range from 3 to 90 percent.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Acker, Atring, Dumont, Kanid, and Norling soils. All of these soils are derived from parent material other than serpentinite. In addition Acker, Kanid and Dumont soils are greater than 40 inches to bedrock. Norling and Acker soils are fine-loamy. Dumont soils are clayey.
DRAINAGE AND PERMEABILITY: Well drained; moderate to very rapid runoff; moderately slow permeability.
USE AND VEGETATION: These soils are used for timber production. Native vegetation includes an overstory of Douglas fir, incense cedar, sugar pine and Jeffery pine. Understory includes cascade Oregongrape, twinflower, insideout flower, western princes pine, Indian dream fern, beargrass and oceanspray. In Curry County, Oregon, the overstory includes tanoak, western white pine, Port-Orford cedar, and knobcone pine with an understory of whiteleaf manzanita, huckleberry oak, and California laurel.
DISTRIBUTION AND EXTENT: Mountainous areas of southwestern Oregon; MLRA 5. The series is inextensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Jackson County Area, Oregon, 1988.
REMARKS: Formerly classified as loamy-skeletal, magnesic, mesic Dystric Xerochrepts, competing series not updated at the time of reclassification.
Diagnostic horizons and features:
Ochric epipedon - after mixing the upper 7 inches has a dry value of 6; 0 to 10 inches.
Cambic horizon - 7 to 29 inches.
Assume base saturation of less than 60 percent throughout from 7 to 29 inches.
Assume a serpentinitic dominated mineralogy.
ADDITIONAL DATA: The pedon was referenced sample for Ca/Mg ratio and base saturation (sum).