LOCATION LARRUPIN WAEstablished Series
TAXONOMIC CLASS: Ashy over loamy-skeletal, amorphic over isotic, frigid Typic Vitrixerands
TYPICAL PEDON: Larrupin ashy loamy sand on a southwest facing, 53 percent convex slope under a coniferous forest at 2,350 feet elevation. (Colors are for moist soil unless otherwise stated. All textures are apparent field textures).
Oi--0 to 2 inches; slightly decomposed needles, twigs, moss. (1 to 2 inches thick)
Oa--2 to 7 inches; black (7.5YR 2/1) highly decomposed organic matter, few fine, medium and coarse roots.
A--7 to 13 inches; brown (10YR 4/3) loamy sand, (65 percent volcanic ash), pale brown (10YR 6/3) dry; weak fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; many fine, few medium roots; 10 percent subrounded and rounded pebbles; slightly acid (pH 6.4); clear wavy boundary. (0 to 9 inches thick)
Bw--13 to 31 inches; dark yellowish brown (10YR 3/4) gravelly ashy sandy loam (30 percent volcanic ash) light yellowish brown (10YR 6/4) dry; single grain; loose; many fine, few medium and coarse roots; 25 percent subrounded and rounded pebbles; slightly acid (pH 6.4); clear smooth boundary. (6 to 20 inches thick)
2BC--31 to 42 inches; dark yellowish brown (10YR 4/6) very gravelly sandy loam, brownish yellow (10YR 6/6) dry; weak fine and medium subangular blocky structure; soft, very friable, slightly sticky and nonplastic; few fine and medium roots; 30 percent pebbles and 10 percent cobbles; slightly acid (pH 6.4); clear irregular boundary. (5 to 17 inches thick)
2C2--42 to 67 inches; yellowish brown (10YR 5/6) very gravelly sandy loam, yellow (10YR 7/6) dry; single grain; loose; 40 percent pebbles and 10 percent cobbles; slightly acid (pH 6.2).
TYPE LOCATION: Snoqualmie Pass Area, Pierce County, Washington; approximately 150 feet north of Forest Service road number 1811, 2,600 feet east and 2,400 feet south of the northwest corner, sec. 34, T. 18 N., R. 7 E.
RANGE IN CHARACTERISTICS: The mean annual soil temperature is 44 to 47 degrees F. Depth to the 2BC horizon is 15 to 26 inches from the mineral soil surface. The soil moisture control section is dry for 45 to 60 consecutive days. The ashy surface mantle has a moist bulk density of 0.60 to 1.00 glcc, it has 30 to 60 percent glass, acid oxalate extractable aluminum plus one-half the iron is more than 2 percent and 15 bar water is 5 to 12 percent on dry samples.
The A horizon has value of 3 or 4 moist, 5 or 6 dry and chroma of 2 or 3 moist or dry. Some pedons have a variegated appearance with 10YR 6/3 and 5/6 colors. Some pedons have an E horizon.
The Bw horizon has hue of 7.5YR or 10YR, value of 3 through 5 moist, 4 through 6 dry, and chroma of 2 through 4 moist or dry. Some pedons have pockets of ash that are 10YR 6/2 and 7/2 moist. It is sandy loam or loamy sand modified by 10 to 35 percent by volume gravel. It has 2 to 10 percent field estimated clay.
The 2BC horizon has hue of 10YR or 2.5Y, value of 4 or 5 moist, 5 through 7 dry, and chroma of 4 through 6 moist or dry. It is modified by 30 to 45 percent pebbles and 5 to 15 percent cobbles by volume.
The 2C horizon has hue of 10YR or 2.5Y, value of 4 or 5 moist, 5 to 7 dry, and chroma of 2 to 6 moist and dry. It is sandy loam or loamy sand with 35 to 60 percent coarse fragments.
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Larrupin soils are on valley bottoms and mountain sideslopes at elevations of 1,700 to 2,800 feet. Slopes range from 3 to 65 percent. The Larrupin soils formed in coarse volcanic ash overlying a volcanic mudflow. The climate is marine influenced with relatively cool, dry summers and cool, wet winters. The mean annual precipitation is 60 to 90 inches. The mean January temperature is about 30 degrees F; mean July temperature is about 60 degrees F; and the mean annual temperature is about 44 degrees F. The frost-free season is 130 to 160 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Grotto, Playco, Nagrom, Pitcher and Littlejohn soils. Grotto soils are sandy-skeletal and lack any ashy mantle. Playco and Nagrom soils are cryic. Pitcher and Littlejohn soils have an ashy mantle 7 to 14 inches thick.
DRAINAGE AND PERMEABILITY: Well drained, moderate permeability, slow to medium runoff.
USE AND VEGETATION: Used for timber production, watershed, and wildlife habitat. Vegetation is Douglas-fir, western hemlock, western redcedar and red alder with an understory of vine maple, salal, red huckleberry, Oregon-grape, western swordfern, trailing blackberry, and mosses.
DISTRIBUTION AND EXTENT: Western slopes of the central Cascade Mountains adjacent to Mount Rainer; MLRA 3. Series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Snoqualamie Pass Area, Pierce County, Washington, 1987.
REMARKS: Diagnostic horizons and features recognized in this pedon are an ochric epipedon and cambic horizon.