LOCATION CRATER LAKE OREstablished Series
TAXONOMIC CLASS: Ashy, amorphic, mesic Typic Vitrixerands
TYPICAL PEDON: Crater Lake fine sandy loam, forested. (Colors are for moist soil unless otherwise noted.)
Oi--1 1/2 inches to 0; loose, organic litter of undecomposed twigs, needles and leaves and partially decomposed organic matter.
A--0 to 2 inches; very dark brown (10YR 2/2) fine sandy loam, grayish brown and brown (10YR 5/2 and 5/3) dry; weak very fine granular structure; soft, very friable, nonsticky and nonplastic; many very fine to medium roots; slightly acid (pH 6.1); abrupt wavy boundary. (1 to 5 inches thick)
Bw--2 to 15 inches; strong brown (7.5YR 4/6) fine sandy loam, light yellowish brown (10YR 6/4) dry; massive; soft, very friable, nonsticky and nonplastic; common very fine to medium roots; slightly acid (pH6.4); gradual smooth boundary. (2 to 25 inches thick)
C1--15 to 21 inches; yellowish brown (10YR 5/6) fine sandy loam, very pale brown (10YR 7/3) dry; massive; soft, very friable, nonsticky and nonplastic; few very fine to medium roots; slightly acid (pH 6.1); gradual smooth boundary. (5 to 10 inches thick)
C2--21 to 70 inches; variegated yellowish brown (10YR 5/4) and light grayish brown (10YR 6/2) fine sandy loam, very pale brown (10YR 8/4) dry; massive; soft, very friable, nonsticky and nonplastic; few very fine to medium roots; moderately acid (pH 5.9); gradual smooth boundary. (24 to 60 inches thick)
C3--70 to 96 inches; very pale brown (10YR 7/4) fine sandy loam, white (10YR 8/2) dry; massive; soft, very friable, nonsticky and nonplastic; moderately acid (pH 5.9).
TYPE LOCATION: Douglas County, Oregon; NE1/4NW1/4 sec. 7, T. 30 S., R. 1 E.
RANGE IN CHARACTERISTICS: The mean annual soil temperature is 47 to 52 degrees F. The soils are usually moist, but are dry in the control section for the 45 to 60 consecutive days during the summer months. Depth to bedrock is 60 inches or more. Thickness of the ash is 40 to 60 inches or more. The ash deposits overlie a variety of rocks and mixed kinds of alluvium. The particle-size control section contains over 60 percent vitric material and is estimated to have 5 to 10 percent clay. It has a moist bulk density of 0.75 to 0.90 g/cubic centimeter throughout and an estimated phosphate retention of more than 25 percent, acid oxalate extractable aluminum plus one-half iron of more than 0.4 percent, and 15-bar moisture of less than 12 percent based on an air-dried sample. The solum is 10 to 30 inches thick.
The A horizon has hue of 10YR or 7.5YR, value of 2 through 4 moist, 4 through 6 dry and chroma of 2 through 4 moist and dry.
The Bw horizon has hue of 10YR or 7.5YR, value of 3 through 5 moist, 5 through 7 dry, and chroma of 4 through 6 moist and 3 or 4 dry. It has weak prismatic or subangular blocky structure or is massive. It is sandy loam, fine sandy loam or very fine sandy loam.
The C horizon has hue of 7.5YR through 2.5Y, value of 4 through 6 moist, 6 through 8 dry, and chroma of 3 through 6 moist and 2 through 4 dry. It is sandy loam, gravelly sandy loam, fine sandy loam or very fine sandy loam. It has 0 to 25 percent gravel and 0 to 10 percent cobbles.
COMPETING SERIES: This is the Thowson (T) series. Thowson soils are dry for 75 to 90 consecutive days after the summer solstice and have 30 to 60 percent volcanic glass in the particle-size control section.
GEOGRAPHIC SETTING: The Crater Lake soils are on plateaus and escarpments at elevations of 1,000 to 4,000 feet. Slopes range from 0 to 70 percent. The soils formed in ash. The mean annual precipitation is 40 to 60 inches. The mean annual temperature is 45 to 50 degrees F; mean January temperature is 25 to 32 degrees F; mean July temperature is 64 degrees F. The frost-free period is 100 to 160 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Acker, Alcot, Barhiskey, Coyata, Deatman, Dumont, Fives, Freezener and Vena soils. All of these soils except for Alcot lack significant amounts of ash in their profile. Alcot soils are ashy-pumiceous.
DRAINAGE AND PERMEABILITY: Well drained; moderately rapid permeability.
USE AND VEGETATION: This soil is used for timber production, water supply, and wildlife habitat. Vegetation is mostly Douglas fir, white fir, western hemlock, sugar pine, ponderosa pine, ceanothus, trailing blackberry, vine maple, cascade Oregongrape, twinflower and princes pine.
DISTRIBUTION AND EXTENT: Valleys in the west side of the central and southern Cascades of Oregon; MLRA 3, 5. The series is inextensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: South Umpqua Area, Oregon, 1974.
REMARKS: This draft reflects a change in classification from Ashy mesic Typic Vitrandepts based on the Andisol Order.
Diagnostic horizons and features:
Ochric epipedon - mollic colors only present in upper 2 inches.
Cambic horizon - 2 to 15 inches.
Particle-size control section - from 0 to 40 inches (A, Bw, C1, and upper 19 inches of C2 horizon)
ADDITIONAL DATA: Partial characterization data on one profile reported in the Soil Survey of South Umpqua Area, Oregon, 1973. Analyses by Oregon State University.