LOCATION TERMO CAEstablished Series
TAXONOMIC CLASS: Very-fine, smectitic, mesic Xerertic Natrargids
TYPICAL PEDON: Termo silty clay - Rangeland, on a 1 percent slope under a cover of Wyoming big sagebrush and greasewood at an elevation of about 5,300 feet. (When described April 10, 1980, the soil was moist throughout. Colors are for dry soil unless otherwise noted.)
A--0 to 2 inches; light brownish gray (10YR 6/2) silty clay, dark grayish brown (10YR 4/2) moist; moderate thin and medium platy structure; hard, very friable, sticky and plastic; common very fine and fine roots; many very fine and common fine interstitial pores; mildly alkaline (pH 7.6); abrupt smooth boundary. (2 to 5 inches thick)
BA--2 to 5 inches; light brownish gray (10YR 6/2) clay, dark grayish brown (10YR 4/2) moist; moderate very fine and fine angular blocky structure; hard, friable, sticky and plastic; common very fine and fine roots; many very fine and fine tubular and interstitial pores; SAR is 12; mildly alkaline (pH 7.6); clear wavy boundary. (2 to 5 inches thick)
Btn1--5 to 12 inches; pale brown (10YR 6/3) clay, dark brown (10YR 4/3) moist; weak fine prismatic structure parting to moderate fine and medium angular blocky; very hard, friable, very sticky and very plastic; common very fine and fine few medium roots; common very fine and fine and few fine tubular pores; few thin and moderately thick clay films on peds and in pores; few pressure faces; SAR is 14; mildly alkaline (pH 7.6); clear wavy boundary.
Btn2--12 to 18 inches; pale brown (10YR 6/2) clay; dark brown (10YR 4/3) moist; weak fine and medium prismatic structure parting to moderate medium and coarse angular blocky; very hard, friable, very sticky and very plastic; common very fine, fine and medium and few coarse roots; common very fine and few fine pores; common moderately thick clay films on peds and in pores; SAR is 19; mildly alkaline (pH 7.8); gradual smooth boundary. (The combined thickness of the Btn horizons is 10 to 15 inches).
BCtn1--18 to 26 inches; pale brown (10YR 6/3) clay, dark brown (10YR 4/3) moist; weak fine and medium prismatic structure parting to moderate medium and coarse angular blocky; hard, very friable, sticky and plastic; common very fine and fine and few medium roots; common very fine and few fine pores; few thin clay films on peds and in pores; SAR is 22; moderately alkaline (pH 8.4); gradual smooth boundary.
BCtn2--26 to 38 inches; grayish brown (10YR 5/2) clay, very dark grayish brown (10YR 3/2) moist; weak fine and medium prismatic structure parting to moderate medium and coarse angular blocky; hard, very friable, sticky and plastic; few very fine and few fine roots; common very fine and few fine tubular pores; few thin clay films on peds and in pores; SAR is 19; moderately alkaline (pH 8.4); clear wavy boundary. (The combined thickness of the BCtn horizons is 16 to 22 inches).
C--38 to 51 inches; light brownish gray (10YR 6/2) silty clay, dark grayish brown (10YR 4/2) moist; weak medium subangular blocky structure; hard, very friable, sticky and plastic; common very fine, few fine and medium roots; few very fine and fine pores; SAR is 17; moderately alkaline (pH 8.4); gradual wavy boundary. (5 to 14 inches thick)
Cy1--51 to 60 inches; light brownish gray (2.5Y 6/2) silty clay, dark grayish brown (2.5Y 4/2); weak medium and coarse angular blocky structure; hard, friable, very sticky and plastic; few very fine roots; few very fine pores; SAR is 17; few fine and medium soft masses and crystals of gypsum; slightly effervescent, lime is disseminated; moderately alkaline (pH 8.4); clear wavy boundary. (9 to 31 inches thick)
Cy2--60 to 65 inches; white (5Y 8/2) loam, pale yellow (5Y 8/3) moist; massive; hard, friable, slightly sticky and slightly plastic; common medium and large soft masses of gypsum and crystals 1 to 8 mm across; SAR is 19; slightly effervescent, lime is disseminated; moderately alkaline (pH 8.4).
TYPE LOCATION: About 2.2 miles north of Ravendale on the dirt road east of the landing strip at Ravendale; 1,900 feet east and 500 feet north of the southwest corner of Section 2, T. 34 N., R. 14 E.
RANGE IN CHARACTERISTICS: The thickness of the solum ranges from 20 to 47 inches. Depth to gypsum ranges from 26 to 60 inches. The organic carbon content of the upper 16 inches ranges from 0.8 to 1.5 percent. The mean annual soil temperature ranges from 48 to 52 degrees F. The mean January soil temperature varies from 60 to 63 degrees F. The mean July soil temperature exceeds 41 degrees F from April 1 to December 1 (245 days). The soil moisture control section is moist throughout from about December 1 to about May 1. It is dry throughout from June 15 to November 15. (150 days)
The A horizon is 10YR 5/2, 5/3, 6/2 or 6/3. Moist color is 10YR 3/2, 3/3, 4/2 or 4/3. After mixing, the upper 7 inches has a dry value greater than 5.5. Reaction is neutral or mildly alkaline. Structure is weak or moderate, thin, medium or thick platy or is weak or moderate fine or medium subangular blocky. Clay content ranges from 50 to 55 percent.
The BA horizon is 10YR 6/2, 7/3 or 7.5YR 5/4. Moist color is 10YR 3/2, 3/3, 4/2, 4/3; 7.5YR 3/4 or 4/4. Reaction is mildly or moderately alkaline.
The Btn horizon is 10YR 6/2, 6/3, 6/4 or 7.5YR 6/4. Moist color is 10YR 4/2, 4/3, 4/4; 7.5YR 3/4 or 4/4. Texture is clay with a weighted average of 60 to 65 percent clay and less than 5 percent sand. Reaction is mildly or moderately alkaline. SAR ranges from 14 to 25. Few to common pressure faces occur in this horizon.
The C and Cy horizons are 10YR 5/4, 6/2, 6/4; 2.5Y 6/2, 6/4, or 5Y 8/2. Moist color is 10YR 3/4, 4/2, 4/4; 2.5Y 4/2, 4/4 or 5Y 8/3. Clay content ranges from 50 to 60 percent in the C horizon to 20 to 45 percent in the Cy horizon. Reaction is mildly or moderately alkaline. Few or common fine to large soft bodies and crystals of gypsum occur in the lower part of the horizon.
COMPETING SERIES: There are no other soils in this family. Catnip soils are similar. Catnip soils are 20 to 40 inches deep to bedrock and are frigid.
GEOGRAPHIC SETTING: Termo soils are in nearly level lake basins and on lake terraces. Slopes are 0 to 2 percent. These soils formed in old lake basin alluvium weathered dominantly from basalt, andesite and tuff. Elevation is 4,400 to 5,400 feet. The climate is semiarid with warm, dry summers and cold, moist winters. The mean annual precipitation varies from 8 to 10 inches. The mean annual temperature is about 45 degrees F, mean January temperature is about 26 degrees F, and mean July temperature is about 64 degrees F. Frost-free period is 60 to 90 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Ravendale (T), Saddlerock (T) and Yobe soils. Ravendale soils have cracks more than 1 cm wide that extend from the surface to over 20 inches that open and close every year. Saddlerock soils have mollic epipedon and are poorly drained. Yobe soils are fine-silty and are poorly drained.
DRAINED AND PERMEABILITY: Moderately well drained; very slow runoff; very slow permeability. These soils are subject to common flooding for brief to long periods from December to May.
USE AND VEGETATION: Termo soils are used for rangeland. Vegetation is Wyoming big sagebrush, greasewood, and saltgrass.
DISTRIBUTION AND EXTENT: Northeastern California. These soils are moderately extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES PROPOSED: Lassen County, California; 1959. The name is from the nearby village of Termo.
REMARKS: This revision changes the classification from fine, montmorillonitic, mesic Xerollic Paleargids to very fine, mixed mesic Xerollic Natrargids. Characterization sample #S81CA-035-0071-1 through 9.
Diagnostic horizons and features recognized in the pedon are:
Ochric epipedon--The zone from the surface of the soil to a depth of 5 inches (A, BA horizons).
Natric Horizon--The zone from about 5 to 18 inches (Btn1, Btn2 horizons).
Very Fine family--The particle size control section (5 to 18 inches) weighted average clay content is 65 percent.