LOCATION LAPHAM                  OR

Established Series
Rev. RJK-GLG-JVC-JBF
04/2011

LAPHAM SERIES

The Lapham series consists of very deep, somewhat excessively drained soils that formed in volcanic ash over lacustrine deposits derived from volcanic rocks. Lapham soils are on lake terraces. Slopes are 0 to 30 percent. The mean annual precipitation is about 230 mm and the mean annual temperature is about 7 degrees C.

TAXONOMIC CLASS: Ashy over loamy-skeletal, glassy over isotic, frigid Vitritorrandic Haploxerolls

TYPICAL PEDON: Lapham gravelly ashy sandy loam--on a 1 percent slope under basin big sagebrush at about 1,352 meter elevation--rangeland. (Colors are for dry soil unless otherwise noted.)

A1--0 to 5 cm; grayish brown (10YR 5/2) gravelly ashy sandy loam, very dark brown (10YR 2/2) moist; weak fine granular structure; soft, very friable, nonsticky and nonplastic; many fine and very fine and common medium roots; many very fine interstitial and few fine tubular pores; 30 percent very pale brown (10YR 7/3) medium to very coarse sand-size pumiceous ash grains; 15 percent gravel; slightly acid (pH 6.1); clear wavy boundary. (5 to 15 cm thick)

A2--5 to 41 cm; grayish brown (10YR 5/2) gravelly ashy sandy loam, very dark brown (10YR 2/2) moist; weak fine and medium subangular blocky structure; soft, very friable, nonsticky and nonplastic; many very fine, many fine, and common medium roots; common very fine and fine tubular pores; 20 percent very pale brown (10YR 7/3) medium to very coarse sand-size pumiceous ash grains; 15 percent gravel; neutral (pH 6.6); gradual wavy boundary. (25 to 50 cm thick)

2Bw--41 to 51 cm; brown (10YR 5/3) extremely gravelly ashy loam, dark brown (10YR 3/3) moist; moderate medium and fine subangular blocky structure; slightly hard, friable, slightly sticky and nonplastic; few very fine and few fine roots; common very fine and fine tubular pores; 15 percent very pale brown (10YR 7/3) medium to very coarse sand-size pumiceous ash grains; 10 percent cobbles and 50 percent gravel; neutral (pH 6.8); gradual wavy boundary. (10 to 25 cm thick)

2C--51 to 152 cm; pale brown (10YR 6/3) extremely gravelly ashy sandy loam, brown (10YR 4/3) moist; massive; soft, very friable, slightly sticky and nonplastic; few very fine and few fine roots; common very fine and fine tubular pores; 15 percent cobbles and 65 percent gravel; neutral (pH 7.2).

TYPE LOCATION: Lake County, Oregon; about 6 miles south of the community of Fort Rock near a gravel pit west of the county road; approximately 925 feet west and 910 feet north of the southeast corner of section 33, T. 26 S., R. 14 E.; USGS Fort Rock 7.5 minute topographic quadrangle; latitude 43 degrees 16 minutes 01 second N and longitude 121 degrees 03 minutes 28 seconds W; NAD 83.

RANGE IN CHARACTERISTICS:
Soil moisture: Usually moist in winter and early spring; aridic soil moisture regime that borders on xeric.
Mean annual soil temperature: 7 to 8degrees C.
Mollic epipedon thickness: 30 to 56 cm.
Depth to buried horizon and strongly contrasting materials: 40 to 66 cm.
Vitrandic intergrade properties: Volcanic glass content: 30 to 50 percent in coarse silt through fine sand fractions of the upper part and 10 to 25 percent in the lower part; Oxalate extractable aluminum plus one-half oxalate extractable iron: 0.2 to 0.4 percent.
Other features: The soil contains a relatively high percentage of dark colored minerals or rock fragments especially in the lower part.

Particle-size control section - Clay content: 5 to 15 percent in the upper part and averages 6 to 16 percent in the lower part.
Rock fragments: 15 to 35 percent in the upper part and 60 to 85 percent in the lower part, mainly gravel. Lithology of fragments are volcanic rocks such as basalt and tuff-breccia.

A1 horizon
Value: 2 or 3 moist.
Chroma: 2 or 3, dry or moist.
Organic matter content: 2 or 3 percent.
Reaction: Slightly acid or neutral.
Other features: Visible grains of medium to very coarse sand-size pumiceous ash ranges from 15 to 30 percent by volume.

A2 horizon
Value: 2 or 3 moist.
Chroma: 2 or 3, dry or moist.
Texture: Gravelly ashy sandy loam or gravelly ashy loamy sand.
Rock fragments: 15 to 35 percent gravel.
Organic matter content: 1 or 2 percent.
Reaction: Slightly acid or neutral.
Other features: Visible grains of medium to very coarse sand-size pumiceous ash ranges from 15 to 30 percent by volume.

2Bw horizon
Value: 5 or 6 dry, 3 or 4 moist.
Chroma: 2 or 3, dry or moist.
Clay content: 10 to 20 percent.
Rock fragments: 60 to 85 percent total; 50 to 75 percent gravel, 0 to 15 percent cobbles.
Other features: Visible grains of medium to very coarse sand-size pumiceous ash ranges from 10 to 20 percent by volume; Some pedons have cambic horizons when horizon thickness is 6 inches or more.

2C horizon
Value: 6 or 7 dry, 4 or 5 moist.
Chroma: 2 or 3, dry or moist.
Clay content: 5 to 15 percent.
Rock fragments: 60 to 85 percent total; 45 to 70 percent gravel, 0 to 20 percent cobbles.
Other features: Visible grains of medium to very coarse sand-size pumiceous ash ranges from 0 to 20 percent by volume and decreases with depth.

COMPETING SERIES: There are currently no other series in this family.

GEOGRAPHIC SETTING: Lapham soils are on lake terraces. These soils formed in volcanic ash over lacustrine deposits derived from volcanic rocks such as basalt and tuff-breccia. Slopes are 0 to 30 percent. Elevations range from 1,310 to 1,460 meters. The climate is semiarid and characterized by cold, moist winters and warm, dry summers. The mean annual precipitation is 200 to 280 mm. The mean annual temperature is 6 to 7 degrees C., The frost-free period is 50 to 90 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Bonnick, Fort Rock, and Kunceider soils. Bonnick soils are ashy, have sandy textures, and have mollic epipedons. Fort Rock soils are ashy over sandy or sandy-skeletal and have mollic epipedons. Kunceider soils are shallow to lithic contacts.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Somewhat excessively drained; low surface runoff; high saturated hydraulic conductivity.

USE AND VEGETATION: Lapham soils are used mainly for rangeland. A few areas are used for irrigated cropland. The vegetation in rangeland is mainly bluebunch wheatgrass, basin big sagebrush, Idaho fescue, and scattered western juniper.

DISTRIBUTION AND EXTENT: South-central Oregon. These soils are not extensive with about 8,500 acres of the series mapped to date. MLRA 23.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California.

SERIES ESTABLISHED: Lake County (Northern Part), Oregon, 2006. The name is from a reservoir.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - The zone from the soil surface to 41 cm (A1 and A2 horizons).
Vitrandic intergrade feature - The zone from the soil surface to 41 cm (A1 and A2 horizons).
Major lithologic discontinuity - The abrupt change to loamy-skeletal material at 41 cm (2Bwb and 2C horizons).
Particle-size control section - The zone from 25 to 100 cm (2Bwb horizon and parts of the A2 and 2C horizons).

The mineralogy classes are estimated based on the properties of similar soils in the area.

---

National Cooperative Soil Survey
U.S.A.