LOCATION RIVERPOINT IDEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, mesic Ultic Argixerolls
TYPICAL PEDON: Riverpoint loam -- on a 3 percent convex southwest-facing slope at 3,080 feet elevation in pastureland. When described on August 25, 1997, the soil was dry throughout. (Colors are for air-dry soil unless otherwise noted.)
A--0 to 6 inches; brown (10YR 5/3) loam, dark brown (10YR 3/3) moist; moderate thin and medium platy structure; slightly hard, very friable, slightly sticky and slightly plastic; many very fine and fine, few medium roots; common very fine and fine, few medium irregular pores; 10 percent gravel; moderately acid (pH 6.0); clear smooth boundary. (3 to 10 inches thick)
AB--6 to 11 inches; brown (10YR 5/3) loam, dark brown (10YR 3/3) moist; moderate fine and medium subangular blocky structure; hard, friable, slightly sticky and slightly plastic; common very fine and fine, few medium roots; common very fine and fine, few medium tubular pores; 10 percent gravel; moderately acid (pH 5.8); clear smooth boundary. (0 to 6 inches thick)
Bt1--11 to 14 inches; pale brown (10YR 6/3) clay loam, brown (10YR 4/3) moist; moderate fine and medium subangular blocky structure; hard, firm, moderately sticky and moderately plastic; common very fine and fine roots; common very fine and fine, few medium tubular pores; many faint clay films on faces of peds and in pores; 10 percent gravel; moderately acid (pH 5.7); clear wavy boundary. (0 to 5 inches thick)
Bt2--14 to 19 inches; light yellowish brown (10YR 6/4) very gravelly clay loam, dark yellowish brown (10YR 4/4) moist; moderate fine and medium subangular and angular blocky structure; hard, firm, moderately sticky and moderately plastic; common very fine and fine roots; common very fine and fine, few medium tubular pores; many distinct clay films on faces of peds and in pores; 35 percent gravel, 5 percent cobbles; 10 percent pararock fragments; moderately acid (pH 5.8); gradual smooth boundary. (5 to 30 inches thick)
2Bt3--19 to 31 inches; light yellowish brown (10YR 6/4) very gravelly coarse sandy loam, yellowish brown (10YR 5/4) moist; weak fine subangular blocky structure; slightly hard, friable, nonsticky and nonplastic; few very fine and fine roots; few very fine and fine tubular and irregular pores; common distinct clay films in pores and bridging sand grains; 50 percent gravel, 5 percent cobbles; 10 percent pararock fragments; moderately acid (pH 6.0); gradual smooth boundary. (0 to 20 inches thick)
2CBt--31 to 41 inches; light yellowish brown (10YR 6/4) very gravelly coarse sandy loam, yellowish brown (10YR 5/4) moist; massive; slightly hard, very friable, nonsticky and nonplastic; few very fine and fine roots; few very fine and fine tubular and irregular pores; common faint clay films in pores and bridging sand grains; 50 percent gravel, 5 percent cobbles; 10 percent pararock fragments; slightly acid (pH 6.1); clear wavy boundary. (0 to 10 inches thick)
2C--41 to 60 inches; brownish yellow (10YR 6/6) extremely gravelly loamy coarse sand, dark yellowish brown (10YR 4/6) moist; single grain; loose, nonsticky and nonplastic; 60 percent gravel, 5 percent cobbles; 10 percent pararock fragments; slightly acid (pH 6.2).
TYPE LOCATION: Boise County, Idaho; about 1 mile northwest of Garden Valley; 100 feet north of the center of section 22, T.9 N., R.4 E.; USGS Garden Valley Quadrangle; Latitude - 44 degrees, 06 minutes, 00 seconds N. and Longitude - 115 degrees, 58 minutes, 04 seconds W.; NAD 83.
RANGE IN CHARACTERISTICS:
Thickness of mollic epipedon - 10 to 15 inches
Depth to base of argillic horizon - 25 to 40 inches
Depth to lithologic discontinuity - 15 to 40 inches
Depth to bedrock - 60 inches or more
Base saturation - 50 to 75 percent in some part between 10 and 30 inches
Particle-size control section - 18 to 27 percent clay; 35 to 60 percent rock fragments
Reaction - moderately acid or slightly acid
Moisture control section - dry 60 to 90 consecutive days following the summer solstice
Average annual soil temperature - 47 to 50 degrees F.
O horizons occur in some pedons
A horizon
Hue - 7.5YR or 10YR
Chroma - 2 or 3 dry or moist
Rock fragments - 0 to 15 percent gravel, 0 to 5 percent cobbles and stones
Bt1 horizon (when present)
Hue - 7.5YR or 10YR
Value - 5 or 6 dry, 3 or 4 moist
Chroma - 3 or 4 dry or moist
Texture - L or CL
Clay content - 22 to 30 percent
Rock fragments - 10 to 25 percent gravel, 0 to 5 percent cobbles, 0 to 5 percent stones and 0 to 35 percent total
Bt2 horizon
Hue - 7.5YR or 10YR
Value - 5 or 6 dry, 3 or 4 moist
Texture - L or CL
Clay content - 22 to 30 percent
Rock fragments - 25 to 40 gravel, 0 to 15 percent cobbles, 0 to 15 percent stones and 35 to 60 percent total
Pararock fragments - 0 to 15 percent
2Bt3 horizon (when present)
Hue - 7.5YR or 10YR
Value - 6 or 7 dry, 4 or 5 moist
Chroma - 4 through 6 dry or moist
Texture - SL, COSL or SCL
Clay content - 10 to 22 percent
Rock fragments - 25 to 50 gravel, 5 to 20 percent cobbles, 0 to 20 percent stones and 50 to 75 percent total
Pararock fragments - 0 to 15 percent
2C horizon
Hue - 7.5YR or 10YR
Value - 6 or 7 dry, 4 or 5 moist
Chroma - 4 through 6 dry or moist
Texture - SL, COSL, LS or LCOS
Clay content - 2 to 12 percent
Rock fragments - 35 to 60 percent gravel, 5 to 35 percent cobbles, 0 to 25 percent stones and 60 to 85 percent total
Pararock fragments - 0 to 25 percent
COMPETING SERIES: These are the Balake , Beezee, Bluesprin, Fordice, Hunsinger, Jebe , Jellico , Keuterville, Legall , Nashmead, Sauter , Shanks (T), Sienna and Tekoa series. Balake and Keuterville soils have an argillic horizon to a depth of 60 inches or more. In addition, Keuterville soils are dry for 45 to 60 consecutive days. Beezee soils have a mollic epipedon 15 to 20 inches thick and a mean annual soil temperature of 50 to 53 degrees F. Bluesprin, Jellico Shanks and Sienna soils have a lithic contact at 20 to 40 inches. Fordice soils do not have an activity class designated, but have greater than 40 percent rock fragments throughout the solum and a mean annual soil temperature of 52 to 57 degrees F. Hunsinger soils are 40 to 60 inches deep to a weathered basalt paralithic contact. Jebe soils have an argillic horizon to a depth of 40 to 60 inches or more and are dry 45 to 60 consecutive days. Legall soils have a mollic epipedon 15 to 20 inches thick, a mean annual soil temperature of 50 to 53 degrees F. and an argillic horizon to a depth of 60 inches or more. Nashmead soils are dry more than 90 days and have a mean annual soil temperature of 54 to 59 degrees F. Sauter have an argillic horizon to a depth of 40 to 60 inches or more and a mollic epipedon 15 to 20 inches thick. Tekoa soils are moderately deep to a paralithic contact.
GEOGRAPHIC SETTING: Riverpoint soils are gently sloping to moderately steep on shoulders and risers of relict lakebed terraces and convex areas of fan remnants at elevations of 2,950 to 3,900 feet. These soils formed in alluvium from igneous rocks (dominantly granodiorite) mixed with lacustrine sediments in the upper part. Slopes range from 2 to 25 percent. Average annual precipitation is 20 to 26 inches. Average annual temperature is 45 to 48 degrees F. Frost-free period is 90 to 120 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Hellake and Stardust soils. These soils are fine-loamy and occur on less convex geomorphic positions.
DRAINAGE AND PERMEABILITY: Well drained; slow to rapid runoff; moderately slow permeability.
USE AND VEGETATION: Riverpoint soils are used mainly for irrigated hayland/pasture and woodland grazing. Some areas are used for homesites. Native vegetation is ponderosa pine and common snowberry.
DISTRIBUTION AND EXTENT: West-central Idaho. MLRA 44. Riverpoint soils are of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Boise County Area, Idaho, Parts of Ada and Boise Counties, 2005.
REMARKS: Diagnostic horizons and features recognized in this pedon:
Mollic epipedon - zone from 0 to 11 inches (A1 and AB horizons)
Argillic horizon - zone from 11 to 31 inches (Bt1, Bt2 and 2Bt3 horizons)
Particle-size control section - zone from 11 to 31 inches
Soil moisture regime - xeric