LOCATION SPANAWAY WAEstablished Series
TAXONOMIC CLASS: Medial-skeletal over sandy or sandy-skeletal, amorphic over isotic, mesic Typic Melanoxerands
TYPICAL PEDON: Spanaway gravelly sandy loam - fern-grass prairie. (Colors are for moist soil unless otherwise stated.)
Oa--0 to 1 inch; black (10YR 2/1) well decomposed organic matter, very dark brown (10YR 2/2) dry; mostly from grass roots and moss. (0 to 1 1/2 inches thick)
A--1 to 15 inches; black (10YR 2/1) gravelly sandy loam, very dark grayish brown (10YR 3/2) dry; weak fine granular structure; soft, very friable, nonsticky and nonplastic; many fine roots; very high in organic matter content, has mellow, sooty feel; 35 percent pebbles; strongly acid (pH 5.4); clear smooth boundary. (10 to 20 inches thick)
Bw--15 to 19 inches; dark grayish brown (10YR 4/2) very gravelly sandy loam, grayish brown (10YR 5/2) dry; weak fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; common fine roots; 50 percent pebbles, 10 percent cobbles; moderately acid (pH 5.8); clear smooth boundary. (3 to 8 inches thick)
2C--19 to 61 inches; light brownish gray (10YR 6/2) dry; extremely gravelly sand; single grained; loose; few fine roots; 60 percent pebbles, 10 percent cobbles; slightly acid (pH 6.1).
TYPE LOCATION: Pierce County, Washington; 1 mile south of Spanaway, east of Pacific Avenue in the SE1/4SW1/4 sec. 33, T. 19 N., R. 3 E.
RANGE IN CHARACTERISTICS: Solum thickness ranges from 14 to 28 inches. Content of coarse fragments in the control section averages 50 to 90 percent. Mean annual soil temperature ranges from 48 to 54 degrees F. These soils are usually moist but are dry in the moisture control section for 75 to 90 consecutive days following summer solstice. The weighted average texture of the control section is very gravelly loamy sand to extremely gravelly sand. The melanic epipedon (also umbric) is 10 to 20 inches thick.
The A horizon has hue of 10YR through 5YR, value of 2 to 4 dry, and chroma of 1 or 2 moist and dry. It has weak granular or blocky structure and is medium acid or strongly acid.
The Bw horizon has value of 4 or 5 dry and 3 or 4 moist. It is very gravelly sandy loam, very gravelly loam or extremely gravelly sandy loam. It has weak fine or medium blocky structure and is strongly acid to slightly acid.
The 2C horizon has hue of 7.5YR to 2.5Y, value of 5 or 6 dry and 4 or 5 moist and chroma of 2 through 4 dry or moist. It is extremely gravelly sand or extremely gravelly loamy sand. It is massive or single grained and is slightly acid or neutral.
COMPETING SERIES: This is the Carstairs series and the similar Bonneville and Sequim series. Carstairs soils are very strongly acid in the A horizon, strongly acid in the B horizon, and are dry for less than 75 consecutive days in the moisture control section. Bonneville soils lack a cambic horizon. Sequim soils have a mollic epipedon.
GEOGRAPHIC SETTING: Spanaway soils are on glacial outwash terraces and plains at elevations of about 100 to 500 feet. Slopes are 0 to 15 percent. These soils formed in glacial outwash and volcanic ash. These soils are in a maritime climate with cool, dry summers and mild, wet winters. The average annual precipitation ranges from 35 to 65 inches. The mean annual temperature is about 51 degrees F. The frost-free season is 150 to 200 days and the growing season (28 degrees F.) is 200 to 240 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Nisqually and Spana soils. Nisqually soils are sandy. Spana soils are loamy-skeletal and have an umbric epipedon more than 20 inches thick.
DRAINAGE AND PERMEABILITY: Somewhat excessively drained; slow runoff; moderately rapid permeability.
USE AND VEGETATION: Used for woodland, pasture, cropland, homesites and wildlife habitat. Native vegetation is Douglas-fir, Oregon white oak, lodgepole pine, and red alder with an understory of salal, western brackenfern, western swordfern, scotchbroom, common snowberry, red huckleberry, Oregon-grape, rose, creambush oceanspray, Indian plum, Solomons-seal and Idaho fescue.
DISTRIBUTION AND EXTENT: Southwestern Washington. Series is of moderate extent.
MLRA OFFICE RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Pierce County, Eastern Puget Sound Basin Reconaissance, Washington, 1909.
REMARKS:
ADDITIONAL DATA: Partial laboratory data pedon 72C0076 and 04N0762.