LOCATION JACKMAN WAEstablished Series
TAXONOMIC CLASS: Ashy-skeletal over loamy-skeletal, amorphic over magnesic Alic Haplocryands
TYPICAL PEDON: Jackman gravelly loam - on a 55 percent east-facing slope under a coniferous canopy of western hemlock and Pacific silver fir. (Colors are for moist soil unless otherwise stated. All textures are apparent field textures.)
0i--4 inches to 0; undecomposed forest litter. (4 to 15 inches thick)
Bs1--0 to 4 inches; strong brown (7.5YR 4/6) gravelly loam, reddish yellow (7.5YR 6/6) dry; weak medium subangular blocky structure; slightly hard, friable, slightly sticky, slightly plastic, and weakly smeary; many very fine roots; common very fine irregular pores; 30 percent rounded pebbles; strongly acid (pH 5.2); clear wavy boundary. (3 to 8 inches thick)
Bs2--4 to 15 inches; dark yellowish brown (10YR 4/6) very gravelly loam, brownish yellow (10YR 6/6) dry; weak medium subangular blocky structure; slightly hard, friable, slightly sticky, slightly plastic, and weakly smeary; common very fine and fine roots; common very fine irregular pores; 30 percent rounded pebbles, 10 percent cobbles; very strongly acid (pH 5.0); abrupt wavy boundary. (9 to 15 inches thick)
2C1--15 to 27 inches; olive brown (2.5Y 4/4) very gravelly loam, light yellowish brown (2.5Y 6/4) dry; weak medium subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; common very fine irregular pores; 35 percent rounded pebbles, 10 percent cobbles; strongly acid (pH 5.2); clear wavy boundary. (7 to 15 inches thick)
2C2--27 to 60 inches; olive (5Y 4/3) very gravelly sandy loam, pale olive (5Y 6/3) dry; massive; soft, very friable, nonsticky and nonplastic; common fine irregular pores; 40 percent rounded pebbles, 10 percent cobbles; very strongly acid (pH 5.0).
TYPE LOCATION: Skagit County, Washington; about 5 miles northwest of Concrete; 1,505 feet north and 2,430 feet east of the southwest corner, sec. 19, T. 36 N., R. 8 E.
RANGE IN CHARACTERISTICS: The mean annual soil temperature is 43 to 46 degrees F. Thickness of the solum is 15 to 36 inches. The weighted average of rock fragments in the particle-size control section ranges from 35 to 60 percent including 0 to 5 percent cobbles. Reaction is very strongly acid to medium acid throughout.
The Bs horizon has hue of 5YR, 7.5YR, or 10YR, value of 4 or 5 moist, 5 or 6 dry, and chroma of 4 through 6 moist and dry. It is gravelly loam or gravelly silt loam in the upper part and very gravelly loam or very gravelly silt loam in the lower part.
The 2C horizon has hue of 7.5YR, 10YR, 2.5Y, or 5Y, value of 4 through 6 moist, 6 or 7 dry, and chroma of 3 through 6 moist and dry. It is very gravelly loam, very gravelly sandy loam, or extremely gravelly loam.
COMPETING SERIES: These are the Klawatti, and Twinsi soils. Klawatti soils are 20 to 40 inches deep to a lithic contact. Twinsi soils are 20 to 40 inches deep to a paralithic contact with dense glacial till.
GEOGRAPHIC SETTING: Jackman soils are on glacially modified mountains with slopes of 30 to 65 percent. The range in elevation is 2,200 to 4,200 feet. The soils formed in volcanic ash and colluvium and slope alluvium from glacial till influenced by dunite. The average annual precipitation is 75 to 90 inches. They are in a marine climate with cool, dry summers and cold, wet winters. The average January temperature is about 30 degrees F., and the average July temperature is about 57 degrees F. The mean annual temperature is 41 to 43 degrees F. The frost-free season is 90 to 110 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Klawatti and Twinsi soil and the Crinker, Edfro, Humskel, Kindy, Potchub, and Saar soils. Crinker, and Humskel soils are moderately deep to a lithic contact. Edfro soils are 14 to 20 inches deep to a paralithic contact with dense glacial till. Kindy, Potchub, and Saar soils are 30 to 40 inches deep to a paralithic contact with dense glacial till.
DRAINAGE AND PERMEABILITY: Well drained; medium or rapid runoff; moderately rapid permeability.
USE AND VEGETATION: Used for woodland and wildlife habitat. Native vegetation consists of Pacific silver fir, western hemlock, and Alaska-cedar with an undergrowth of tall blue huckleberry, deer fern, western rattlesnake plantain, strawberryleaf raspberry, plantain, and western brackenfern.
DISTRIBUTION AND EXTENT: Twinsister Mountains area on the west slopes of the Cascade Mountains in northwestern Washington. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Skagit County Area, Washington, 1981.
REMARKS: Classification only changed 4/94 because of recent amendments to Soil Taxonomy. This draft reflects a change in classification from loamy-skeletal, serpentinitic Typic Cryorthods to loamy-skeletal, serpentinitic Alic Haplocryands. Diagnostic features recognized in this pedon are: andic soil materials from the surface to 15 inches and 45 percent dunite fragments in the particle-size control section.