LOCATION MOKINS IDEstablished Series
TAXONOMIC CLASS: Fine, smectitic Vitrandic Haplocryalfs
TYPICAL PEDON: Mokins silt loam, forested. (Colors are for dry soil unless otherwise noted.)
Oi--0 to 1.5 inches; needles, twigs, and grass.
A-1.5 to 4 inches; brown (10YR 5/3) silt loam, very dark grayish brown (10YR 3/2) moist; moderate fine granular structure; soft, friable, slightly sticky and nonplastic; many fine and medium roots; common very fine and fine irregular pores; 5 percent gravel; neutral; (pH 6.6); abrupt wavy boundary. (0 to 4 inches thick)
B21ir--4 to 7 inches; light yellowish brown (10YR 6/4) silt loam, strong brown (7.5YR 5/6) moist; weak thick platy structure that parts to moderate medium subangular blocky; soft, friable, slightly stick and nonplastic; many fine, medium and few coarse roots; common very fine and fine irregular pores; 5 percent gravel; slightly acid (pH 6.2); clear wavy boundary. (3 to 8 inches thick)
B22ir--7 to 15 inches; very pale brown (10YR 7/4) gravelly silt loam, strong brown (7.5YR 5/6) moist; moderate and coarse subangular blocky structure; hard, friable, slightly stick and slightly plastic; common fine and medium roots; many very fine and fine irregular pores; 23 percent gravel; moderately acid (pH 6.0); abrupt wavy boundary. (8 to 12 inches thick)
Eb--15 to 21 inches; very pale brown (10YR 8/2) silt loam, light yellowish brown (10YR 6/4) moist; common faint to distinct reddish yellow (7.5YR 6/6) redox concentrations on surfaces of peds; weak medium subangular blocky structure; hard, firm, slightly sticky and slightly plastic; many fine roots; many very fine and fine tubular pores; 5 percent gravel; very strongly acid (pH 4.6); abrupt irregular boundary. (3 to 6 inches thick)
Bt1b--21 to 29 inches; reddish yellow (7.5YR 6/8) silty clay loam, strong brown (7.5YR 5/8) moist; common distinct reddish yellow (7.5YR 6/6) redox concentrations on surfaces of peds; moderate medium prismatic structure that parts to strong fine and medium angular blocky; very hard, very firm, very sticky and very plastic; few fine and medium roots; common very fine and fine tubular and vesicular pores; thick E material coatings on surfaces of peds; continuous faint yellowish red (5YR 5/8) clay films on surfaces of peds; very strongly acid (pH 4.6); clear wavy boundary. (6 to 10 inches thick)
Bt2b--29 to 50 inches; brownish yellow (10YR 6/8) silty clay, yellowish brown (10YR 5/8) moist; common prominent fine and medium reddish yellow (7.5YR 6/8) redox concentrations; moderate coarse prismatic structure (with plates in prisms) that parts to strong fine angular blocky; very hard, very firm, very sticky and very plastic; few fine and medium roots that are matted on surfaces of peds; common very fine and fine tubular and vesicular pores; continuous prominent yellowish red (5YR 4/6) clay films; thin very pale brown (10YR 8/3) E material coatings on surfaces of peds; very strongly acid (pH 4.6); diffuse wavy boundary. (16 to 22 inches thick)
Bt3b--50 to 60 inches; brownish yellow (10YR 6/8) silty clay; yellowish brown (10YR 5/8) moist; many prominent medium and coarse strong brown (7.5YR 5/8) redox concentrations; moderate coarse prismatic structure that parts to weak medium angular blocky; very hard, very firm, very sticky and very plastic; few fine and medium roots matted on surfaces of peds; common very fine and fine tubular and vesicular pores; continuous faint yellowish red (5YR 5/8) and dark reddish brown (5YR 3/3) clay films; thin patchy white (10YR 8/1) E material coatings on surfaces of peds; very strongly acid (pH 4.8).
TYPE LOCATION: Kootenai County, Idaho; 1,800 feet west of the NE corner of section 5, T. 51 N., R. 3 W.
RANGE IN CHARACTERISTICS: The soil between depths of 6 and 16 inches becomes moist in early November and stays moist until late July or early August. The thickness of the solum ranges from 40 or more than 60 inches thick. Average annual soil temperature is 43 to 45 degrees F. and average summer soil temperature is 45 to 47 degrees F. The solum is neutral to very strongly acid. It contains up to 30 percent rock fragments.
The A horizon has value of 4 or 5 dry, 3 or 4 moist and chroma of 2 or 3 dry and moist. This horizon is commonly silt loam but ranges to loam.
The Bir horizon has hue of 7.5YR or 10YR, value of 5 through 7 dry, 4 through 6 moist and chroma of 3 through 6 dry and moist. It is loam, gravelly silt loam or silt loam.
The Eb horizon has value of 7 or 8 dry, 5 or 6 moist and chroma of 2 through 4 dry and moist.
The Btb horizon has hue of 7.5YR or 10YR, value of 5 through 7 dry, 4 or 5 moist, and chroma of 6 through 8 dry and moist. Redox concentrations range from faint to prominent in hue of 7.5YR or 5YR. Clay films range from faint to prominent and have hue of 7.5YR or 5YR, value of 3 through 6 and chroma of 3 through 8. This horizon is silty clay loam or silty clay and has 35 to 50 percent clay.
COMPETING SERIES: There are no competing series. The similar Savenac series have mixed minerology.
GEOGRAPHIC SETTING: Mokins soils are on undulating to very steep glaciolacustrine terraces and terraces slopes. Elevation range form 2,200 to 2,800 feet. The soils formed in glaciolacustrine sediments mantled with volcanic ash and loess. The climate is characterized by cool, moist winters and warm, dry summers. The average annual precipitation is 25 to 30 inches. The average January temperature is 20 degrees F. and the average July temperature is 59 degrees F. The average annual temperature is 42 to 44 degrees F. The frost-free season is 80 to 100 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Chatcolet and Rubson soils. Chatcolet soils are fine-silty, and Rubson soils are coarse-silty.
DRAINAGE AND PERMEABILITY: Moderately well drained; medium to very rapid runoff; slow permeability. A seasonal perched water table above the argillic horizon is at depths of 14 inches to 30 inches for 30 to 50 days in the spring.
USE AND VEGETATION: The soils are used mainly for woodland with some areas for small grins, hay, and pasture. Native vegetation is mainly grand fir, western whitepine, western larch, Douglas-fir, lodgepole pine, ponderosa pine, myrtle pachistima, queencup beadlily, anemone, rose, and pacific trillium.
DISTRIBUTION AND EXTENT: Kootenai and Shoshone Counties, Idaho. The series is inextensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Kootenai County, Idaho, 1976.