LOCATION THORNTON WAEstablished Series
TAXONOMIC CLASS: Fine-silty, magnesic, nonacid, mesic Aquic Xerorthents
TYPICAL PEDON; Thornton silt loam - on an undissected terrace under mixed conifers. (Colors are for moist soils unless otherwise indicated.)
01--2 to 1 inch; leaves, twigs, and needles.
02--1 inch to 0; decomposed plant material.
A1--0 to 2 inches; grayish brown (2.5Y 5/2) silt loam, light gray (2.5Y 7/2) dry; massive; hard; firm; slightly sticky and plastic; few fine and very fine roots; very few very irregular fine pores; medium acid (pH 5.8); abrupt smooth boundary. (0 to 3 inches thick)
C1--2 to 45 inches; white (2.5Y 8/2) silt loam, white 10YR 8/1) dry; many medium distinct light yellowish brown (10YR 6/4) mottles; very fine stratification; massive; hard, firm, slightly sticky and plastic; few very fine and fine roots; very few very fine pores; medium acid (pH 5.8); gradual irregular boundary. (12 to 50 inches thick)
C2--45 to 60 inches; light gray (5Y 7/2) silt loam, white (5Y 8/1) dry; many medium prominent brownish yellow (10YR 6/6) mottles; very fine stratification; massive; hard, firm, slightly sticky and slightly plastic; medium acid (pH 5.8).
TYPE LOCATION: Skagit County, Washington; 1 mile west of Day Creek, Washington; 500 feet south and 50 feet west of the northeast corner of sec. 25, T. 35 N., R. 5 E.
RANGE IN CHARACTERISTICS: Mean annual soil temperature ranges from 52 to 54 degrees F. Clay content in the control section is 18 to 25 percent.
The A horizon has hue of 10YR or 2.5Y, value of 4 through 6 moist, 6 or 7 dry, and chroma of 1 or 2 moist and dry.
The C horizon has hue of 10YR through 5Y, value of 6 through 8 moist and dry, and chroma of 0 to 2 moist and dry. Mottles increase in size and contrast in the lower part.
COMPETING SERIES: These are the Aloha and Kitsap series in other families. Aloha and Kitsap soils have a cambic horizon and mixed mineralogy.
GEOGRAPHIC SETTING: Thornton soils are on glacial lake terraces with 0 to 3 percent slopes. Elevation is 150 to 250 feet. These soils formed in lacustrine sediments derived from talc of local origin. The mean annual temperature is 50 to 52 degrees F., and the average annual precipitation is 50 to 60 inches. Average January temperature is about 37 degrees F. and average July temperature is about 65 degrees F. The frost-free season is 180 to 220 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Barneston, Giles, and Gilligan soils. Barneston soils are sandy- skeletal. Giles soils are medial and Gilligan soils are coarse-loamy.
DRAINAGE AND PERMEABILITY: Somewhat poorly drained; slow runoff; slow permeability.
USE AND VEGETATION: Used primarily for woodland or pasture. Native vegetation is Sitka spruce, Douglas-fir, western hemlock, western redcedar, paper birch, red alder, false lily-of-the-valley, lady fern, and western swordfern.
DISTRIBUTION AND EXTENT: Northwestern Washington. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Skagit County, Washington, l953.
REMARKS: Classification is satisfactory (3/94). Low chroma are lithic chromatic in nature and are not a result of iron reduction.
ADDITIONAL DATA: Partial laboratory data are available on this soil. National Soil Survey Lab. number 797528.