LOCATION SKOOKUM OREstablished Series
TAXONOMIC CLASS: Clayey-skeletal, smectitic, mesic Pachic Ultic Argixerolls
TYPICAL PEDON: Skookum very cobbly loam in rangeland and on a 44 percent slope. (Colors are for moist soil unless otherwise
noted.)
A--0 to 3 inches; very dark brown (10YR 2/2) very cobbly
loam, dark grayish brown (10YR 4/2) dry; weak very fine and fine granular structure; soft, very friable, slightly sticky and
slightly plastic; many very fine roots; many very fine irregular pores; 15 percent gravel, 30 percent cobbles and 5 percent
stones; neutral (pH 7.2); abrupt wavy boundary. (2 to 7 inches thick)
BAt--3 to 8 inches; very dark grayish brown (10YR 3/2) very
cobbly loam, dark grayish brown (10YR 4/3) dry; moderate fine and medium subangular blocky structure; hard, firm, slightly sticky
and slightly plastic; few very fine roots; few very fine tubular pores; few thin clay films on peds and in pores; 10 percent
gravel and 25 percent cobbles; neutral (pH 7.0); clear wavy
boundary. (4 to 8 inches thick)
Bt1--8 to 16 inches; very dark grayish brown (10YR 3/2) very
cobbly clay loam, dark grayish brown (10YR 4/2) dry; moderate
fine subangular blocky structure; very hard, firm, sticky and plastic; few very fine roots; few very fine tubular pores; few
thin clay films on peds and in pores; 10 percent gravel and 45 percent cobbles; neutral (pH 6.7); gradual wavy boundary. (6 to
12 inches thick)
Bt2--16 to 22 inches; dark brown (7.5YR 3/3) very cobbly
clay, brown (7.5YR 4/2) dry; moderate fine and medium subangular blocky structure; very hard, very firm, very sticky and very
plastic; few medium roots; few very fine tubular pores; few thin
clay films on peds and in pores; 10 percent gravel and 50 percent cobbles; neutral (pH 6.7); gradual wavy boundary. (4 to 12
inches thick)
Bt3--22 to 28 inches; dark brown (7.5YR 3/4) extremely cobbly
clay, brown (7.5YR 4/2) dry; moderate fine angular blocky
structure; very hard, very firm, very sticky and very plastic;
few roots; few very fine tubular pores; few thin clay films on
peds and in pores; 40 percent cobbles and 30 percent stones;
neutral (pH 6.7); abrupt irregular boundary. (5 to 13 inches
thick)
R--28 inches; hard fractured andesite.
TYPE LOCATION: Jackson County, Oregon; about 6 miles south of Pinehurst; approximately 1,650 feet west and 40 feet north of the southeast corner of sec. 4, T. 41 S., R. 4 E.
RANGE IN CHARACTERISTICS: Depth to a lithic contact is 20 to 40 inches. The mean annual soil temperature is 47 to 54 degrees F.
The soils are usually moist but are dry between 4 and 12 inches
for 70 to 100 consecutive days during the summer months. The particle-size control section averages 40 to 80 percent rock fragments of which 5 to 10 percent are gravel, 30 to 45 percent
are cobbles and 5 to 25 percent are stones.
The A horizon has value of 2 or 3 moist and 3 or 4 dry; and
chroma of 2 or 3 moist or dry.
The Bt horizon has hue of 10YR or 7.5YR, value of 3 moist, 3 or 4 dry, chroma of 2 to 4 moist and 2 or 3 dry. It is very cobbly
clay loam, very cobbly clay or extremely cobbly clay and is 35 to
50 percent clay.
COMPETING SERIES: There are no other series.
GEOGRAPHIC SETTING: Skookum soils are on mountainsides and hills
at elevations of 2,000 to 4,800 feet. Slopes are 1 to 70
percent. The soils formed in colluvium weathered from extrusive igneous rock. The mean annual precipitation is 18 to 35 inches.
The mean annual temperature is 45 to 52 degrees F. The
frost-free period is 100 to 150 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Carney,
Geppert,
Hukill,
McMullin and
McNull soils. Carney and Hukill soils lack mollic epipedons and are non-skeletal. McNull soils are
non-skeletal and have a mollic epipedon less than 20 inches
thick. McMullin soils are shallow and non-skeletal. Geppert
soils are loamy-skeletal.
DRAINAGE AND PERMEABILITY: Well drained; medium to rapid runoff; slow permeability.
USE AND VEGETATION: The soils are used mainly for range and
wildlife habitat. Native vegetation is Oregon white oak, western juniper, ponderosa pine, wedgeleaf ceanothus, Idaho fescue, and Lemmon needlegrass.
DISTRIBUTION AND EXTENT: Western slope of the southern Cascades. The series is inextensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Jackson County Area, Oregon, 1988.