LOCATION DONEGAN OREstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, frigid Humic Dystroxerepts
TYPICAL PEDON: Donegan gravelly loam, forested. (Colors are for moist soil unless otherwise noted.)
Oi--0 inches to 3; partially decomposed leaves, needles, and twigs.
A--3 to 13 inches; dark brown (7.5YR 3/2) gravelly loam, brown (7.5YR 4/2) dry; strong fine and medium granular structure; soft, very friable, nonsticky and nonplastic; common very fine and fine roots; many very fine irregular pores; 25 percent gravel and 5 percent cobbles; slightly acid (pH 6.4); abrupt smooth boundary. (2 to 10 inches thick)
BA--13 to 25 inches; dark brown (7.5YR 3/2) gravelly loam, brown (7.5YR 4/2) dry; moderate very fine and fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine, fine, medium, and coarse roots; common very fine and fine tubular pores; 25 percent gravel and 9 percent cobbles; slightly acid (pH 6.4); clear wavy boundary. (0 to 15 inches thick)
Bw--25 to 35 inches; dark brown (7.5YR 3/2) extremely gravelly loam, brown (7.5YR 4/2) dry; moderate very fine and fine subangular blocky structure; hard, friable, slightly sticky and slightly plastic; common very fine, fine, medium, and coarse roots; common very fine and fine tubular pores; 45 percent gravel and 20 percent cobbles; slightly acid (pH 6.2); abrupt irregular boundary. (10 to 35 inches thick)
Cr--35 inches; basalt.
TYPE LOCATION: Jackson County, Oregon; approximately 200 feet north and 600 feet east of the southwest corner of sec. 35, T. 33 S., R. 2 E., 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 43 to 47 degrees F. Depth to a paralithic contact and thickness of the umbric epipedon is 20 to 40 inches. The particle-size control section averages 18 to 35 percent clay, 20 to 50 percent gravel, and 15 to 40 percent cobbles. It is moderately acid or slightly acid.
The A horizon has hue of 5YR or 7.5YR, value of 2 or 3 moist, 3 through 5 dry, and chroma of 2 or 3 moist and dry. It has 10 to 40 percent gravel and 5 to 10 percent cobbles.
The Bw horizon has hue of 5YR or 7.5YR, value of 3 or 4 moist, 4 or 5 dry, and chroma of 2 or 3 moist and 3 or 4 dry. It has 20 to 35 percent clay, 20 to 60 percent gravel, and 10 to 40 percent cobbles. It is a very cobbly loam, extremely gravelly loam, extremely gravelly clay loam, or very gravelly clay loam.
COMPETING SERIES: These are the Bearcamp, Brandypeak, Burnlake, Freezeout, Goodwin, Nanny, Snowbrier, Tallac and Undusk series. The Bearcamp soils are deep to a lithic contact. Brandypeak soils have a 10 to 14 inch thick umbric epipedon. Burnlake soils are very deep and have a 10 to 20 inch thick umbric epipedon. Freezeout soils have 10 to 18 percent clay in the particle size control section and have a 10 to 20 inch thick umbric epipedon. Goodwin soils are deep to a paralithic contact. Nanny soils are very deep. Snowbrier soils have hues of 10YR to 5Y, have a 10 to 20 inch thick umbric epipedon and are dominated by schist rock fragments. Tallac soils are 40 to 60 inches deep to a cemented or compacted layer. Undusk soils are very deep.
GEOGRAPHIC SETTING: Donegan soils are on ridges and hillslopes at elevations of 4,000 to 5,100 feet. These soils formed in colluvium derived from igneous rock and volcanic ash. The mean annual precipitation is 40 to 50 inches. The mean annual temperature is 41 to 45 degrees F. The frost-free period is less than 100 days. Slopes range from 3 to 65 percent.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Coyata, Dumont, and Killet soils. Coyata and Dumont soils are mesic. In addition, Dumont soils are clayey and deeper than 40 inches to bedrock. Killet soils are fine-loamy and over 40 inches to bedrock.
DRAINAGE AND PERMEABILITY: Well drained; slow to rapid runoff; moderately slow permeability.
USE AND VEGETATION: These soils are used for timber production. Native vegetation includes an overstory of Douglas fir, white fir, western hemlock, incense cedar, golden chinkapin, and Pacific dogwood. Understory includes western fescue, cascade Oregongrape, western princes pine, twinflower, vine maple, deltoid anenome, toothed pyrola, marbled wild ginger, and deerfoot vanillaleaf.
DISTRIBUTION AND EXTENT: Southwestern Oregon in MLRA 5. The series is not extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Jackson County Area, Oregon, 1988.
REMARKS: Diagnostic horizons and features:
- Umbric epipedon - 3 to 35 inches.
- Cambic horizon - 25 to 35 inches.
- Assume a base saturation of less than 50 percent throughout the profile.