LOCATION TERRABELLA OREstablished Series
TAXONOMIC CLASS: Fine, smectitic, mesic Vertic Argiaquolls
TYPICAL PEDON: Terrabella clay loam, on a 1 percent slope in a meadow. (Colors are for moist soil unless otherwise noted.)
O--1 inch to 0; a mat of grass roots.
A--0 to 5 inches; very dark brown (10YR 2/2) clay loam, very dark grayish brown (10YR 3/2) dry; few fine prominent reddish yellow (5YR 6/8) and few fine distinct red (2.5YR 4/8) mottles; strong fine granular structure; hard, very friable, sticky and plastic; many very fine and few fine roots; many very fine and common fine irregular pores; 5 percent gravel; moderately acid (pH 5.6); clear smooth boundary. (4 to 8 inches thick)
BA--5 to 10 inches; very dark brown (7.5YR 2/2) clay loam, dark
brown (7.5YR 3/2) dry; few fine distinct red (2.5YR 4/8) mottles; moderate very fine and fine subangular blocky structure; very hard, firm, sticky and very plastic; common very fine and few fine, medium and coarse roots; few very fine irregular pores; few stress surfaces; 5 percent gravel; moderately acid (pH 5.6); clear smooth boundary. (3 to 8 inches thick)
Bt1--10 to 16 inches; dark reddish brown (5YR 3/3) clay, dark
reddish gray (5YR 4/2) dry; few fine distinct yellowish red (5YR 5/8) and red (2.5YR 4/8) mottles; strong medium subangular blocky structure; very hard, firm, very sticky and very plastic; few very fine to coarse roots; few very fine tubular pores; many stress surfaces, many thin clay films in pores; 5 percent gravel; slightly acid (pH 6.2); clear smooth boundary. (4 to 7 inches thick)
Bt2--16 to 28 inches; dark reddish gray (5YR 4/2) clay, reddish
gray (5YR 5/2) dry; few fine distinct yellowish red (5YR 5/8), very dark gray (5YR 3/1) and red (2.5YR 4/8) mottles; strong medium and coarse prismatic structure; extremely hard, extremely firm, very sticky and very plastic; few medium and coarse roots; few very fine tubular pores; many stress surfaces, continuous clay films in pores; 5 percent gravel; slightly acid (pH 6.3); gradual smooth boundary. (10 to 14 inches thick)
Bt3--28 to 50 inches; dark brown (7.5YR 3/4) clay, brown (7.5YR
5/4) dry; common fine distinct yellowish red (5YR 5/6) and few fine distinct yellowish red (5YR 5/8) mottles; weak coarse angular blocky structure; extremely hard, extremely firm, very sticky and very plastic; few medium roots; few very fine tubular pores; continuous thick clay films on ped faces and in pores; 5 percent gravel; slightly acid (pH 6.3); diffuse smooth boundary. (20 to 24 inches thick)
C--50 to 60 inches; dark yellowish brown (10YR 4/4) gravelly clay loam, light yellowish brown (10YR 6/4) dry; many medium distinct yellowish red (5YR 5/6) mottles; massive; very hard, firm, sticky and plastic; 15 percent gravel; slightly acid (pH 6.4).
TYPE LOCATION: Jackson County, Oregon; about 5.5 miles northeast of Butte Falls, approximately 1,625 feet west and 2,270 feet south of the northeast corner of sec. 21, T. 34 S., R. 3 E.
RANGE IN CHARACTERISTICS: Depth to bedrock is 60 inches or more. The particle-size control section averages 40 to 55 percent clay and 0 to 5 percent gravel. The mean annual soil temperature is 49 to 54 degrees F. The profile is cracked from the surface to a depth of 21 to 30 inches from late July through late September. The mollic epipedon is 10 to 15 inches thick. The solum contains distinct or prominent mottles throughout.
The A horizon has hue of 10YR or 7.5YR, value of 2 or 3 moist, 3 or 4 dry, and chroma of 2 or 3 moist and dry.
The Bt horizon has hue of 5YR or 7.5YR, value of 3 or 4 moist, 4 or 5 dry, and chroma of 2 through 4 moist and dry.
The C horizon has hue of 5YR through 10YR, value of 4 or 5 moist, 6 or 7 dry, and chroma of 3 or 4 moist and dry. It is clay loam, gravelly clay loam or clay, with 35 to 55 percent clay and 0 to 20 percent gravel.
COMPETING SERIES: There are no competing series in this family.
GEOGRAPHIC SETTING: Terrabella soils are on alluvial flats at elevations of 1,500 to 3,500 feet. Slopes are 0 to 3 percent. The soils formed in alluvium dominantly from basic igneous rock. The mean annual temperature is about 45 to 52 degrees F. The mean annual precipitation is 25 to 45 inches. The frost-free period is 100 to 150 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Freezener, Geppert, Hukill, Medco, and McNull soils. The Freezener, Geppert, McNull, and Hukill soils are well drained. The Medco soils are moderately well drained and are moderately deep.
DRAINAGE AND PERMEABILITY: Poorly drained; ponded to slow runoff; slow permeability. The soils have rare flooding and have a water table from 6 inches above the surface to 12 inches below the surface from December through May.
USE AND VEGETATION: Terrabella soils are used for pasture, water supply, recreation, and wildlife. Native vegetation is dominantly tufted hairgrass with some sedges. There are some scattered stands of ponderosa pine and Oregon ash.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
DISTRIBUTION AND EXTENT: Southern Cascades of southwestern Oregon. The soils are of small extent.
SERIES ESTABLISHED: Jackson County Area, Oregon, 1988.
REMARKS: Diagnostic horizons and features:
Mollic epipedon - from the surface to a depth of 16 inches.
Argillic horizon - from a depth of 16 to 50 inches.
Stress surfaces are present to a depth of 28 inches (evidence of cracking).