LOCATION THORN OREstablished Series
TAXONOMIC CLASS: Loamy-skeletal, isotic, frigid Lithic Mollic Haploxeralfs
TYPICAL PEDON: Thorn gravelly ashy sandy loam - woodland, on a 15 percent slope at 3100 feet. (When described (8/28/85), the soil was dry throughout. Colors are for moist soil unless otherwise noted)
Oi--0 to 1 inch; slightly decomposed litter of ponderosa pine and grasses.
A1--1 to 5 inches; dark brown (10YR 3/3) gravelly ashy sandy loam, grayish brown (10YR 5/2) dry; weak medium granular structure; slightly hard, friable, nonsticky and nonplastic; many very fine, fine, and medium roots; many fine interstitial pores; 15 percent gravel and 5 percent cobbles; 10 percent estimated clay; neutral (pH 7.0); clear wavy boundary. (4 to 7 inches thick)
2A2--5 to 9 inches; brown (10YR 4/3) loam; light brownish gray (10YR 6/2) dry; weak medium subangular blocky structure; slightly hard, friable, nonsticky and nonplastic; common very fine, fine, and medium roots; many very fine tubular pores; 12 percent estimated clay; neutral (pH 7.0); clear wavy boundary. (1 to 6 inches thick).
2Btb--9 to 17 inches; brown (7.5YR 4/4) extremely cobbly loam, light brown (7.5YR 6/4) dry; moderate medium subangular blocky structure; hard, firm, nonsticky and slightly plastic; few coarse roots; common very fine tubular pores; common distinct clay films on peds and on rock surfaces; 40 percent cobbles, 20 percent stones, and 15 percent gravel; 20 percent estimated clay; neutral (pH 7.2); clear wavy boundary. (5 to 10 inches thick)
2R--17 inches; andesite
TYPE LOCATION: Deschutes County, Oregon; on USFS road 1160, 0.5 miles west of the junction with USFS road 1160-410; northeast quarter of section 8, T.12 S, R. 10 E. (Latitude 44 degrees, 32 minutes, 54 seconds N, Longitude 121 degrees, 33 minutes, 24 seconds W)
RANGE IN CHARACTERISTICS: The soil moisture control section is usually moist but is dry in all parts for 60 to 90 consecutive days after the summer solstice. The mean annual soil temperature is 42 to 47 degrees F. Depth to a lithic contact is 10 to 20 inches. The hue of the solum is 10YR or 7.5YR. The soil is neutral throughout. Base saturation is 50 to 75 percent throughout.
The Oi horizon is 1 to 3 inches, except where disturbed.
The A horizon has a value of 2 or 3 moist, 5 or 6 dry and chroma of 3 moist and 2 to 4 dry. It is a sandy loam, with 5 to 18 percent estimated clay. It has 10 to 25 percent subrounded gravels, 0 to 10 percent subrounded to angular cobbles. Total rock fragment content ranges from 15 to 30 percent. It has 50 to 80 percent glass and glass coated aggregate.
The 2A2 horizon has chroma of 3 or 4 moist and 2 to 4 dry. It is loam or gravelly loam with 0 to 25 percent gravel and 0 to 10 percent cobbles. Estimated clay content is 10 to 20 percent.
The 2Btb horizon has chroma of 2 to 4 moist and dry. It is a very cobbly, extremely cobbly or a extremely stony loam with 20 to 27 percent estimated clay. It has 10 to 25 percent angular gravel, 20 to 50 percent angular cobbles and 10 to 40 percent stones. Total rock fragments range from 55 to 80 percent.
Some pedons have a Cr horizon 1 to 3 inches thick.
COMPETING SERIES: These are the Avtable, Blackspar, Cinderhurst, and Wassit series. Avtable soils lack an O horizon, and lack the thin pumice ash surface layer. Blackspar soils lack an O horizon, are dry for 90 to 120 cumulative days and lack the thin pumice ash surface. Cinderhurst soils are 4 to 10 inches to basalt bedrock. Wassit soils lack the thin pumice ash surface and an O horizon.
GEOGRAPHIC SETTING: Thorn soils are on uplands at elevations of 3,000 to 4,000 feet. Slopes are 15 to 50 percent. The soils formed in ash over colluvium and residuum weathered from andesite or ash flow tuffs. The climate is characterized by cold, wet winters and hot, dry summers. The mean annual precipitation is 15 to 25 inches. The mean annual temperature is 40 to 47 degrees F. The frost-free period is 50 to 90 days.
GEOGRAPHICALLY ASSOCIATED SOILS: This is the Parrego soils. Parrego soils are on uplands, moderately deep to bedrock and are fine-loamy.
DRAINAGE AND PERMEABILITY: Well drained; moderate permeability.
USE AND VEGETATION: These soils are used for timber production, wildlife habitat, and recreation. Potential native vegetation is ponderosa pine, antelope bitterbrush, greenleaf manzanita, and Idaho fescue.
DISTRIBUTION AND EXTENT: East slope of the Cascade Mountains in Central Oregon; MLRA 6. The series is not extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Jefferson County (Upper Deschutes River Area), Oregon, 1992.
REMARKS: Diagnostic horizons and feature in this pedon:
ochric epipedon -
argillic horizon - from 8 to 16 inches (2Btb horizon)
The upper 4 inches of the A horizon has andic soil properties.
Mollic subgroup - the upper 4 inches has value of 3 moist and over 1 percent organic matter
Lithic subgroup - hard rock at 17 inches.