LOCATION UMPA CA+NV
Established Series
Rev. JHR/GMK/TDC/ET
01/2023
UMPA SERIES
The Umpa series consists of moderately deep, well-drained soils that formed in material weathered from andesite. Umpa soils are on uplands and have slopes of 5 to 75 percent. The mean annual precipitation is about 40 inches and the mean annual temperature is about 40 degrees F.
TAXONOMIC CLASS: Loamy-skeletal, isotic, frigid Andic Dystroxerepts
TYPICAL PEDON: Umpa series - on a south facing convex slope of 40 percent under a cover of mixed conifers at 7,400 feet elevation. (Colors are for dry soil unless otherwise noted). When described October 16, 1968, the soil was moist to 10 inches and dry below.
Oi--0 to 2 inches; fir litter and duff.
A--2 to 5 inches; dark grayish brown (10YR 4/2) very stony sandy loam, very dark brown (10YR 2/2) moist; weak fine granular structure; soft, very friable, nonsticky and nonplastic; common very fine and fine roots; many very fine interstitial pores; 10 percent stones and boulders and 25 percent pebbles; moderately acid (pH 6.0); abrupt smooth boundary. (2 to 4 inches thick)
AB--5 to 13 inches; pale brown (10YR 6/3) gravelly sandy loam, brown (10YR 4/3) moist; weak fine granular structure; soft, very friable, nonsticky and nonplastic; many very fine, fine and medium, common coarse roots; many very fine and fine interstitial pores; 30 percent pebbles; moderately acid (pH 6.0); clear smooth boundary. (4 to 7 inches thick)
BA--13 to 32 inches; very pale brown (10YR 7/3) very gravelly sandy loam, brown (10YR 4/3) moist; massive; soft, very friable, nonsticky and nonplastic; many very fine, fine, medium and coarse roots; many very fine and fine interstitial pores; 50 percent pebbles and 10 percent stones; moderately acid (pH 5.8); clear wavy boundary. (9 to 19 inches thick)
Bw--32 to 42 inches; light gray (10YR 7/1) very gravelly sandy loam, gray (5YR 5/1) and reddish gray (5YR 5/2) moist; weak medium subangular blocky structure; hard, friable, slightly sticky and slightly plastic; common fine and medium roots; common very fine and fine tubular and interstitial pores; few thin clay films in pores and coat sand grains and pebbles; 50 percent pebbles and 10 percent stones; strongly acid (pH 5.5); clear wavy boundary. (5 to 10 inches thick)
R--42 to 60 inches; hard, fractured andesite.
TYPE LOCATION: Placer County, California; road cut on north side of logging road, 3 miles north of Tahoe City; 400 feet west and 100 feet north of south 1/4 corner, sec. 19, T. 16 N., R. 17 E.
RANGE IN CHARACTERISTICS:
Depth to bedrock: ranges from 20 to 40 inches from the mineral surface
Soil Moisture: usually moist between depths of 15 and 40 inches and are dry in all parts from about late July until early October
Soil temperature: The mean annual soil temperature is 40 to 44 degrees F, and the mean summer soil temperature is 50 to 54 degrees F.
Texture of the fine earth: sandy loam or loam
Rock fragments: average more than 35 percent, and range from 30 to 75 percent in individual horizons, mainly gravel but include some cobbles, stones and boulders
Base saturation: 25 to 50 percent
Bulk density is 0.80 to 0.95 gm/cc.
0i horizons are 1 to 3 inches thick.
The A horizon:
Hue: 10YR or 7.5YR
Value: 3 through 5 dry, 2 through 4 moist
Chroma: 2 through 4 dry, 2 through 4; the darker colors are in the surface 3 to 6 inches and do not qualify for an Umbric epipedon
Organic matter: 3 to 6 percent
Reaction: moderately to strongly acid.
The Bw horizon:
Hue: 10YR, 7.5YR or 5YR
Value: 6 or 7 dry, 5 or 6 moist
It has 1 to 3 percent more clay than the A horizon.
Reaction: moderately to very strongly acid.
COMPETING SERIES: These are the
Bertolotti,
Cliffdell,
Deroux,
Littlejohn,
Mountaineer,
Pheeney,
Pitcher,
Roxer and
Scotties soils. Bertolotti, Cliffdell, Pitcher and Roxer soils have bedrock deeper than 60 inches. Deroux soils are formed in sandstone and volcanic ash with 60 percent volcanic ash in the A horizon, and have a mean annual soil temperature of 45 to 47 degrees F. with a frost free period of 145 to 170 days. In the Littlejohn soils, the moisture control section is dry for 45 to 60 consecutive days. Mountaineer soils are 20 to 40 inches deep to compact glacial till. Pheeney soils have an umbric epipedon. Scotties soils are 40 inches or deeper to sandstone bedrock.
GEOGRAPHIC SETTING: The Umpa soils are on gently convex sloping to very steep mountains at elevations of 6,400 to 9,000 feet. They formed in material weathered from coarse textured recent andesitic flows and are often in the vicinity of cinder cones. Stones and boulders are common on the surface. The climate is humid and has mean annual precipitation of about 35 to 55 inches most of which falls as snow. Average annual temperature is 40 degrees F, mean January temperature is 25 degrees F, and the mean July temperature is 60 degrees F. The average frost-free season is 25 to 80 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Jorge,
Tahoma and
Waca soils. Jorge and Tahoma soils have argillic horizons. Waca soils have bulk densities less than 0.95 gm/cc.
DRAINAGE AND PERMEABILITY: Well-drained; medium to rapid runoff; moderately rapid permeability.
USE AND VEGETATION: Timber and watershed; native vegetation is mixed conifers and shrubs with principal species being red fir, white fir, Jeffrey pine, western white pine, prostrate ceanothus, snowbrush, greenleaf manzanita, and mountain whitethorn.
DISTRIBUTION AND EXTENT: The higher elevations of the Sierra Nevada Mountains of California. The soils of this series are of moderate extent. MLRA 22A
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Placer County, Tahoe Basin Area, California, 1970.
REMARKS: The Umpa soils were formerly classified as members of the loamy-skeletal, mixed family of Typic Cryochrepts. Minerology is influenced but not dominated by pyroclastic material. The profile was sampled and determinations were made for particle size distribution, organic carbon, 15 bar water, pH, base saturation, and cation exchange capabity. Correlation sample no. was 69CA-31-7.
National Cooperative Soil Survey
U.S.A.