LOCATION THISTLEBURN OREstablished Series
TAXONOMIC CLASS: Fine, mixed, superactive, frigid Typic Palehumults
TYPICAL PEDON: Thistleburn clay loam, on a south southwest-facing slope of 25 percent under a coniferous forest at an elevation of 3,650 feet. (Colors are for moist soil unless otherwise stated.)
Oi--1/2 inch to 0; slightly decomposed needles, leaves, and twigs.
A--0 to 10 inches; very dark gray (10YR 3/1) clay loam, dark grayish brown (10YR 4/2) dry; moderate very fine, fine, and medium granular structure; hard, firm, very sticky and plastic; many very fine and common fine and medium roots; many very fine irregular pores; very strongly acid; abrupt smooth boundary. (9 to 12 inches thick)
Bt1--10 to 19 inches; dark yellowish brown (10YR 3/4) clay, yellowish brown (10YR 5/4) dry; moderate fine and medium subangular blocky structure; very hard, firm, very sticky and very plastic; common very fine, fine, medium and coarse roots; many very fine irregular pores; common distinct clay films on faces of peds and lining pores; very strongly acid; abrupt wavy boundary. (8 to 15 inches thick)
Bt2--19 to 31 inches; dark yellowish brown (10YR 3/4) clay, yellowish brown (10YR 5/4) dry; moderate medium and coarse subangular blocky structure; very hard, firm, very sticky and very plastic; common very fine, fine, and medium roots; common very fine and fine tubular pores; many prominent clay films on faces of peds and lining pores; very strongly acid; abrupt wavy boundary. (10 to 15 inches thick)
Bt3--31 to 40 inches; dark yellowish brown (10YR 4/6) clay, brownish yellow (10YR 6/6) dry; moderate medium and coarse subangular blocky structure; very hard, very firm, very sticky and very plastic; common very fine, fine, and medium roots; common very fine and fine tubular pores; many prominent clay films on faces of peds and lining pores; very strongly acid; abrupt wavy boundary. (8 to 13 inches thick)
Bt4--40 to 49 inches; yellowish brown (10YR 5/8) clay, yellow (10YR 7/8) dry; moderate medium and coarse subangular blocky structure; very hard, very firm, very sticky and very plastic; few very fine and medium roots; common fine tubular pores; common distinct clay films on faces of peds and lining pores; very strongly acid; clear wavy boundary. (8 to 11 inches thick)
Bt5--49 to 55 inches; strong brown (7.5YR 5/8) silty clay, reddish yellow (10YR 7/8) dry; moderate medium and coarse subangular blocky structure; very hard, firm, very sticky and very plastic; few very fine, fine, and medium roots; common fine tubular pores; common distinct clay films on faces of peds and lining pores; very strongly acid; clear wavy boundary. (5 to 7 inches thick)
BCt--55 to 70 inches; strong brown (7.5YR 5/8) silty clay loam, reddish yellow (10YR 7/8) dry; weak medium and coarse subangular blocky structure; hard, firm, very sticky and plastic; few very fine and fine roots; common fine tubular pores; few distinct clay films on peds and lining pores; very strongly acid.
TYPE LOCATION: Douglas County, Oregon; 2.5 miles east-southeast of Tater Hill; 715 feet west and 1,785 feet south of the NE corner of section 9, T. 29 S., R. 2 W., W. M.
RANGE IN CHARACTERISTICS: Thickness of the solum commonly is 60 inches or more. The mean annual soil temperature is 42 to 47 degrees F., the mean summer soil temperature is greater than 47 degrees F. The soil is usually moist and is dry between 4 and 12 inches for less than 45 consecutive days during the summer. Hue is 10YR or 7.5YR. The upper square meter of the mineral soil contains 12 to 18 kilograms of organic carbon.
The A horizon has value of 2 or 3 moist, 4 or 5 dry and chroma of 1 to 3 moist and 2 or 3 dry. The structure is moderate or strong and very fine, fine or medium. Consistency is slightly hard or hard, friable or firm, slightly sticky to very sticky and slightly plastic or plastic. Rock fragments range from 0 to 15 percent gravel. It is very strongly acid or strongly acid. It has 4 to 8 percent organic matter.
The Bt horizon has value of 3 to 5 moist, 5 to 7 dry and chroma of 4 to 8 moist and dry. The texture is silty clay or clay with 40 to 55 percent clay. Structure is fine, medium or coarse. Consistence is hard or very hard, friable to very firm, sticky or very sticky and plastic or very plastic. Rock fragments range from 0 to 10 percent gravel. It is extremely acid or very strongly acid. Base saturation by sum of bases is 15 to 35 percent throughout. It has 0.5 to 3.0 percent organic matter decreasing with depth.
COMPETING SERIES: This is the Pyrady series. Pyrady soils are moderately well drained and have redoximorphic features at 20 to 30 inches.
GEOGRAPHIC SETTING: Thistleburn soils are on benches and mountain sideslopes. Elevation ranges from 3,000 to 4,400 feet. These soils formed in colluvium and residuum derived dominantly from ash-flow tuffs. Slopes range from 3 to 60 percent. The mean annual temperature ranges from 40 to 45 degrees F. and the mean annual precipitation is 50 to 70 inches. The frost-free season is 50 to 100 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Illahee, Lempira, and Telemon soils. Illahee soils are loamy-skeletal and have cambic horizons. Lempira soils are in the medial family. The Telemon soils are somewhat poorly and moderately well drained.
DRAINAGE AND PERMEABILITY: Well drained; moderately slow permeability.
USE AND VEGETATION: These soils are used for timber production; wildlife habitat and watershed. The native vegetation includes western hemlock, Douglas fir, and grand fir with an understory of Pacific rhododendron, salal, western swordfern, western princes pine, common beargrass, and cascade Oregongrape.
DISTRIBUTION AND EXTENT: Western Cascade Mountains of southern Oregon. MLRA 3. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Douglas County, Oregon, 1994.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Umbric epipedon - the zone from approximately 0 to 10 inches. (A horizon)
Argillic horizon - the zone from approximately 10 to 55 inches (Bt1, Bt2, Bt3, Bt4 and Bt5 horizons). Base saturation is 17 percent by sum of bases at about one meter. It assumed that base saturation will remain the same or decrease with depth.
Pale feature - clay content does not decrease by more than 20 percent from the maximum.
Mixed mineralogy - mineralogy estimated based on previous field experience.
ADDITIONAL DATA: Laboratory data from Oregon State University, pedon number S85-OR-19-(1-4).