LOCATION THORNLAKE OR
Established Series
Rev. GJW-MPK-JVC-JBF
06/2011
THORNLAKE SERIES
The Thornlake series consists of very deep, well drained soils that formed in lacustrine deposits derived from volcanic ash. Thornlake soils are on lakebeds. Slopes are 0 to 5 percent. The mean annual precipitation is about 230 mm and the mean annual temperature is about 7 degrees C.
TAXONOMIC CLASS: Ashy, glassy, frigid Sodic Xeric Haplocambids
TYPICAL PEDON: Thornlake ashy silt loam--on a nearly level lakebed at an elevation of about 1,310 meters--rangeland. (Colors are for dry soil unless otherwise noted. When described on December 7, 1994, the soil was dry throughout.)
A--0 to 18 cm; light brownish gray (10YR 6/2) ashy silt loam, dark grayish brown (10YR 4/2) moist; weak fine subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; many very fine and fine roots; common very fine and fine vesicular pores; moderately alkaline (pH 8.2); clear wavy boundary. (5 to 18 cm thick)
Bn--18 to 64 cm; very pale brown (10YR 7/4) ashy silt loam, yellowish brown (10YR 5/4) moist; moderate fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common fine and few medium roots; common very fine and fine vesicular pores; slightly effervescent; moderately alkaline (pH 8.3); clear smooth boundary. (15 to 48 cm thick)
Bkn--64 to 145 cm; light brownish gray (10YR 6/2) ashy sandy loam, dark grayish brown (10YR 4/2) moist; massive; slightly hard, friable, nonsticky and nonplastic; few fine and medium roots; few fine tubular pores; secondary carbonates are finely disseminated in the matrix; violently effervescent; strongly alkaline (pH 8.6); abrupt smooth boundary. (30 to 127 cm thick)
C--145 to 155 cm; light brownish gray (10YR 6/2) ashy loamy sand, dark grayish brown (10YR 4/2) moist; single grain; loose, nonsticky and nonplastic; few medium roots; few fine tubular pores; strongly effervescent; strongly alkaline (pH 8.6);
TYPE LOCATION: Lake County, Oregon; in Christmas Lake Valley about 6 miles east of the town of Christmas Valley; approximately 3,700 feet north and 1,550 feet west of the southeast corner of section 10, T.27 S., R. 18 E.; USGS Fandango Canyon 7.5 minute topographic quadrangle; latitude 43 degrees 14 minutes 52 seconds N and longitude 120 degrees 34 minutes 12 seconds W; NAD 83.
RANGE IN CHARACTERISTICS:
Soil moisture: Usually moist in the moisture control section in winter and spring, dry in summer and fall; aridic moisture regime that borders on xeric.
Mean annual soil temperature: 7 to 8 degrees C.
Depth to base of cambic horizon: 25 to 66 cm.
Depth to identifiable secondary carbonates: 25 to 66 cm.
Depth to bedrock: More than 150 cm.
Volcanic glass content: 30 to 60 percent in coarse silt through fine sand fractions.
Reaction: Moderately alkaline to very strongly alkaline.
Other features: Some pedons have horizons with weakly cemented pararock fragments between 100 and 150 cm.
Particle-size control section - Clay content: 15 to 25 percent.
A horizon
Value: 5 through 7 dry, 3 through 5 moist.
Chroma: 2 or 3, dry or moist.
Bn horizon
Value: 6 or 7 dry, 4 or 5 moist.
Chroma: 2 through 4, dry or moist.
Texture: Ashy loam or ashy silt loam.
Salinity (EC): 1 or 2 mmhos/cm.
Sodicity (SAR): 13 to 30.
Bkn and C horizons
Value: 6 or 7 dry, 4 or 5 moist.
Chroma: 2 or 3, dry or moist.
Texture: Ashy sandy loam, ashy loam, ashy silt loam, or ashy loamy sand.
Clay content: 5 to 25 percent.
Salinity (EC): 2 to 8 mmhos/cm.
Sodicity (SAR): 13 to 80.
Calcium carbonate equivalent: 1 to 9 percent.
COMPETING SERIES: These are the
Abert and
Tonor series.
Abert soils have surface horizons with over 30 percent visible sand-size pumiceous ash grains and have neutral reaction in the A horizons.
Tonor soils have horizons influenced by diatom grains.
GEOGRAPHIC SETTING: Thornlake soils are on lakebeds. These soils formed in lacustrine deposits derived from volcanic ash. The source of the volcanic ash is ancestral Mt. Mazama. Slopes are 0 to 5 percent. Elevations range from 1,300 to 1,345 meters. The climate is semiarid and characterized by cool, moist winters and warm, dry summers. The mean annual precipitation is 200 to 250 mm, the mean annual temperature is 6 to 7 degrees C, and the frost-free period is 50 to 80 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing
Abert soil and the
Horning and
Salhouse soils. Horning and Salhouse soils have ashy sandy textures in the particle-size control section and occur on stable dunes.
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Well drained; very low or low surface runoff; moderately high saturated hydraulic conductivity.
USE AND VEGETATION: Thornlake soils are used for livestock grazing, irrigated cropland, and wildlife habitat. Alfalfa hay is the main crop. The potential native vegetation in rangeland is black greasewood, basin big sagebrush, green rabbitbrush, gray rabbitbrush, creeping wildrye, and inland saltgrass.
DISTRIBUTION AND EXTENT: South-central Oregon. These soils are moderately extensive. MLRA 23.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California.
SERIES ESTABLISHED: Lake County (Northern Part), Oregon, 2006.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - The zone from the soil surface to 18 cm (A horizon).
Cambic horizon - The zone from 18 to 64 cm (Bn horizon).
Sodic subgroup feature - The zone from 18 to 145 cm (Bn and Bkn horizons).
Identifiable secondary carbonates - The zone from 64 to 155 cm (Bkn and Ck horizons).
Particle-size control section and ashy substitute class with glassy mineralogy - The zone from 25 to 100 cm (parts of the Bn and Bkn horizons).
ADDITIONAL DATA: Three pedons are reference sampled for the Soil Survey Laboratory (SSL), Lincoln, NE, as soil survey sample numbers S96OR-037-001, S96OR-037-002, and S96OR-037-003. Selected data are available. Volcanic glass content on other pedons (SJS99-55, MPK98-8, and GW99NL-3) determined locally by optical grain count with a petrographic microscope.
National Cooperative Soil Survey
U.S.A.