LOCATION HORSEFLAT WAEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, mesic Lithic Argixerolls
TYPICAL PEDON: Horseflat very cobbly loam - rangeland, on a 38 percent north-facing slope at 2,000 feet elevation. (Colors are for dry soil unless otherwise stated. All textures are apparent field textures.)
A--0 to 4 inches brown (10YR 5/3) very cobbly loam, dark brown (10YR 3/3) moist; moderate fine and medium granular structure; soft, friable, nonsticky and nonplastic; many very fine roots; few very fine irregular pores; 20 percent gravel and 25 percent cobbles; slightly alkaline (pH 7.4); clear smooth boundary. (2 to 5 inches thick)
AB--4 to 9 inches; brown (10YR 5/3) very gravelly loam, dark brown (10YR 3/3) moist; moderate fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine and roots; few very fine irregular pores; 30 percent gravel and 10 percent cobbles; slightly alkaline (pH 7.4); clear wavy boundary. (4 to 8 inches thick)
Bt--9 to 16 inches; brown (10YR 5/3) extremely gravelly loam, dark brown (10YR 3/3) moist; medium subangular blocky structure; hard, firm, slightly sticky and slightly plastic; few very fine roots; few very fine tubular pores; common distinct clay films on the faces of peds; 50 percent gravel and 15 percent cobbles; slightly alkaline (pH 7.4); abrupt irregular boundary. (3 to 10 inches thick)
R--16 inches; basalt bedrock, with silica coatings over 30 percent of the surface area of the bedrock.
TYPE LOCATION: Kittitas County, Washington, about 1,200 feet south and 2,900 feet east of the northwest corner of section 31, T. 16 N., R. 23 E.; USGS Beverly topographic quadrangle; Latitude 46 degrees 50 minutes 14 seconds N. and Longitude 119 degrees 59 minutes 22 seconds W.
RANGE IN CHARACTERISTICS: The mean annual soil temperature ranges from 47 to 54 degrees F. The particle-size control section averages 23 to 33 percent clay in the fine earth fraction and 35 to 65 percent rock fragments. These soils are dry in the moisture control section for more than half of the time when soil temperature at the lithic contact is above 40 degrees F. Solum thickness and depth to bedrock ranges from 12 to 20 inches. The mollic epipedon ranges from 7 to 17 inches thick and includes all or part of the argillic. Organic matter is estimated to range from 1 to 2 percent. Reaction is neutral or slightly alkaline throughout.
The A horizon has hue of 10YR or 7.5YR, value of 4 or 5 dry, 2 or 3 moist and chroma of 2 to 4 dry, 2 or 3 moist.
The AB horizon has hue of 10 YR or 7.5YR, value of 4 to 6 dry, 2 to 4 moist and chroma of 2 to 4, dry or moist. Texture is very gravelly clay loam, very gravelly loam or very cobbly loam.
The Bt horizon has hue of 10YR or 7.5YR, value of 3 to 6 dry and the chroma is 2 to 4, dry or moist. Texture is extremely gravelly loam, extremely cobbly loam, very gravelly loam, very cobbly loam or very cobbly clay loam. It averages 35 to 85 percent rock fragments.
COMPETING SERIES: These are the
Argabak,
Bellehelen,
Brier,
Canfire,
Chinabutte,
Clovercreek,
Duco,
Gwin, Maygat (T),
Nuhelen,
Ocud,
Orhood,
Reywat,
Shepridge,
Stepmount,
Upatad, and
Windry.
Argabak soils 4 to 12 inches to a lithic contact (basalt)
Bellehelen soils 7 to 14 inches to a lithic contact (andesitic tuff); usually dry, moist in winter and spring, dry summer and fall except for 10 to 20 days cumulative between July to October due to convection storms
Brier soils 14 to 20 inches to a lithic contact (welded rhyolitic tuff); usually dry, moist in winter and spring, dry summer and fall except for 10 to 20 days cumulative between July to October due to convection storms
Canfire soils 14 to 20 inches to a lithic contact (gneiss); dry for 75 to 90 consecutive days following the summer solstice; particle-size control section has 18 to 25 percent clay and 35 to 60 percent, mainly gravel of metamorphic origin such as schist or gneiss.
Chinabutte soils dry for 75 to 90 consecutive days following the summer solstice; particle-size control section has 35 to 75 percent rock fragments of rhyolitic or andisitic origin
Clovercreek soils dry for 60 to 80 consecutive days following the summer solstice
Duco soils have fractured bedrock of andesitic or rhyolitic origin with illuvial clay, do not have secondary silica coats over 30 percent of the surface area of the bedrock, do not have transitional AB horizons, and do not have more than 35 percent rock fragments in the upper part of the argillic horizon
Gwin soils dry for 60 to 75 consecutive days following the summer solstice
Maygat soils not able to compete; not in OSD database
Nuhelen soild 7 to 14 inches to a lithic contact (welded tuff); 15 to 30 percent volcanic glass throughout
Orcud soils 7 to 14 inches to a lithic contact (andesite or rhyolite); particle-size control section had 15 to 25 percent clay and 60 to 80 percent rock fragments, mainly gravel, rhyolitic or andesitic origin; bedrock does not have secondary silica coatings
Orhood soils does not have secondary silica coatings in bedrock fractures; mean annual soil temperature is above 41 degrees F. between March 15 to December; 5 to 10 percent stones throughout
Reywat soils have identifiable secondary carbonates in the lower part of the Bt horizon, on the surface of the lithic contact, or in cracks within the bedrock; dry for 60 to 80 consecutive days following the summer solstice
Shepridge soils 10 to 20 inches to a lithic contact (quartzite); particle-size control section has 18 to 27 percent clay and 50 to 80 percent rock fragments (dominantly gravel) or quartzite origin; dry for more than 60 consecutive days following the summer solstice
Stepmount soils 10 to 20 inches to lithic contact (andesite); 9 to 18 inches to secondary calcium carbonates (Btk horizon); dry for more than 60 consecutive days following the summer solstice
Upatad soils 5 to 15 percent silica concretions and lime coatings on rock fragments in the 2Btk horizon; mildly to moderately alkaline throughout
Windry soils dry for 90 to 100 consecutive days following the summer solstice
GEOGRAPHIC SETTING: Horseflat soils are on plateaus, ridges, hillslopes and canyon walls. Slopes are 0 to 65 percent. Elevation is 250 to 3,300 feet. The mean annual precipitation is 9 to 14 inches. The average January temperature is about 25 degrees F. and the average July temperature is 69 degrees F. The average annual temperature is 46 to 52 degrees F. The frost-free season is 120 to 180 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Argabak, Benwy, Grinrod, Norod, Ralls, Ralock, Vantage, Winblow, and Zen soils. Argabak soils are on ridges and benches and are 4 to 12 inches to bedrock. Benwy soils are on old alluvial fans and Ralls and Ralock soils are on hillslopes and both are fine-loamy and greater than 40 inches deep. Grinrod soils are on foot slopes and side slopes and Norod and Zen soils are on hillslopes and both are 20 to 40 inches to bedrock. Vantage soils are on plateaus and ridgetops and are clayey-skeletal and 12 to 20 inches to bedrock. Winblow soils are moderately deep and ashy and are on mounds.
DRAINAGE AND PERMEABILITY: Well drained, slow to very rapid runoff; moderately slow permeability.
USE AND VEGETATION: These soils are used mainly for livestock grazing and wildlife habitat. Native vegetation is Sandberg bluegrass, bluebunch wheatgrass, rock eriogonum, and Wyoming big sagebrush.
DISTRIBUTION AND EXTENT: Central Washington. MLRA 8. Series is of small extent
MLRA OFFICE RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Kittitas County, Washington, Yakima Training Center, 1994.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon the zone from 0 to 16 inches
Argillic horizon the zone from 9 to 16 inches
Lithic contact the zone beginning at 16 inches
Particle-size control section - the zone from 9 to 16 inches (argillic horizon)
Aridic soil moisture regime