LOCATION PIRAPEAK                NV

Established Series
Rev. EWB-TM-JVC-JBF
12/2019

PIRAPEAK SERIES

The Pirapeak series consists of very deep, somewhat excessively drained soils that formed in colluvium derived from granitic rocks. Pirapeak soils are on mountains. Slopes are 30 to 75 percent. The mean annual precipitation is about 700 mm and the mean annual temperature is about 3 degrees C.

TAXONOMIC CLASS: Sandy-skeletal, mixed Xeric Haplocryepts

TYPICAL PEDON: Pirapeak extremely bouldery coarse sandy loam--forestland. (Colors are for dry soil unless otherwise noted.) The mineral soil surface is covered with approximately 20 percent gravel, 20 percent cobbles, 20 percent stones, and 20 percent boulders.

Oi--0 to 3 cm; slightly decomposed plant material composed of conifer needle duff; abrupt wavy boundary. (3 to 8 cm thick)

A1--3 to 5 cm; grayish brown (10YR 5/2) extremely bouldery coarse sandy loam, dark brown (10YR 3/3) moist; weak fine subangular blocky structure; soft, very friable, slightly sticky and nonplastic; common very fine roots; common very fine tubular and interstitial pores; 45 percent gravel, 10 percent cobbles, 15 percent stones, and 15 percent boulders; slightly acid (pH 6.2); abrupt smooth boundary. (3 to 8 cm thick)

A2--5 to 15 cm; light brownish gray (10YR 6/2) extremely cobbly coarse sandy loam, brown (10YR 4/3) moist; weak fine subangular blocky structure; soft, very friable, slightly sticky and nonplastic; common very fine and fine roots; common very fine tubular and interstitial pores; 25 percent gravel, 25 percent cobbles, and 10 percent stones; slightly acid (pH 6.2); abrupt wavy boundary. (0 to 10 cm thick)

E1--15 to 43 cm; light gray (10YR 7/2) very cobbly coarse sandy loam, brown (10YR 5/3) moist; weak fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; many very fine through medium, few coarse roots; common very fine tubular and interstitial pores; 25 percent gravel, 25 percent cobbles, and 5 percent stones; slightly acid (pH 6.4); clear wavy boundary. (15 to 30 cm thick)

E2--43 to 71 cm; light gray (10YR 7/2) extremely cobbly loamy coarse sand, brown (10YR 5/3) moist; weak fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; many very fine and fine, common medium, few coarse roots; many very fine and fine interstitial pores; 30 percent gravel, 35 percent cobbles, and 5 percent stones; neutral (pH 6.6); clear wavy boundary. (0 to 38 cm thick)

C1--71 to 104 cm; light brownish gray (10YR 6/2) extremely stony loamy coarse sand, brown (10YR 5/3) moist; massive; soft, very friable, nonsticky and nonplastic; many very fine, few fine and medium roots; many very fine and fine interstitial pores; 20 percent gravel, 25 percent cobbles, and 35 percent stones; neutral (pH 6.8); clear irregular boundary. (13 to 38 cm thick)

C2--104 to 155 cm; pale brown (10YR 6/3) extremely cobbly loamy coarse sand, brown (10YR 5/3) moist; massive; soft, very friable, nonsticky and nonplastic; common very fine roots; many very fine and fine interstitial pores; 30 percent gravel, 35 percent cobbles, and 10 percent stones; slightly acid (pH 6.4).

TYPE LOCATION: White Pine County, Nevada; in Great Basin National Park about 0.67 of a mile east of Johnson Lake; USGS Wheeler Peak 7.5 minute topographic quadrangle; latitude 38 degrees 56 minutes 37 seconds N latitude and longitude 114 degrees 17 minutes 16 seconds W; UTM Zone 11 38.94361111e, 4314018n, WGS84 Decimal Degrees 38.9436111 latitude, -114.2877778 longitude.

RANGE IN CHARACTERISTICS:
Soil moisture - Usually moist in the moisture control section; dry in all parts at least 45 consecutive days following the summer solstice (July and August), but intermittently moist in the upper part for 10 to 20 days cumulative due to convection storms between July and September; snow covered from November through April; upper part is saturated for about 15 to 20 consecutive days during snowmelt in April and/or May; Xeric soil moisture regime.
Mean annual soil temperature - 3 to 5 degrees C.
Mean summer soil temperature - 7 to 8 degrees C.
Ochric epipedon thickness - 30 to 76 cm; includes the Oi, A1, A2 (when present), E1, and E2 (when present) horizons.
Depth to top of albic horizon - 3 to 18 cm measured from the mineral soil surface at the top of the A1 horizon.
Depth to base of cambic horizon - 25 to 46 cm measured from the mineral soil surface at the top of the A1 horizon.
Reaction - Slightly acid or neutral.

Particle-size control section - Clay content: Averages 3 to 10 percent.
Rock fragments: Averages 65 to 85 percent, dominantly cobbles and stones, with the less than 3 inch fraction dominated by fine pebbles. Lithology of fragments is granitic rocks.

A1 horizon and A2 horizon (when present)
Value: 5 or 6 dry, 3 or 4 moist. Value of 5 dry and 3 moist occurs only in A1 horizons
Chroma: 2 or 3, dry or moist.
Clay content: 12 to 18 percent.

E1 horizon
Value: 6 or 7 dry.
Chroma: 2 or 3, dry or moist.
Clay content: 12 to 18 percent.

E2 and C horizons
Value: 6 or 7 dry.
Chroma: 2 or 3, dry or moist.
Clay content: 3 to 10 percent.
Rock fragments: 65 to 85 percent, mainly cobbles and stones.
Other features: The E2 horizon constitutes part of the albic horizon.

COMPETING SERIES: These are the Pikaden , Struggle, and Underdown series.
Pikaden soils do not have albic horizons and have fragmental material between 63 and 125 cm.
Struggle soils do not have albic horizons and have moderately acid or strongly acid A horizons.
Underdown soils are moderately deep to paralithic contacts.

GEOGRAPHIC SETTING: Pirapeak soils are on mountains. They typically occur on backslope positions. These soils formed in colluvium derived from granitic rocks. Slopes are 30 to 75 percent. Elevations range from 2,800 to 3,510 meters. The climate is humid with cold wet winters and cool dry summers. The mean annual precipitation is 600 to 950 mm, the mean annual temperature is 1.5 to 4 degrees C., and the frost-free period is 30 to 50 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Ceebee and Strawbcrek soils.
Ceebee soils have argillic horizons composed of lamellae.
Strawbcrek soils are loamy-skeletal and have horizons with lamellae.

DRAINAGE AND PERMEABILITY: Somewhat excessively drained; medium surface runoff; moderately rapid permeability; high saturated hydraulic conductivity in the upper part over rapid permeability; very high saturated hydraulic conductivity in the lower part.

USE AND VEGETATION: Pirapeak soils are used for recreation, watershed, and wildlife habitat. The potential native vegetation is mainly a forest canopy of Engelmann's spruce and limber pine with a sparse understory of bluegrass sp., muttongrass, and common juniper. This site is correlated to Ecological Site F28AY083NV, Engelmann's spruce-mountain gooseberry-mountain brome and needlegrass.

DISTRIBUTION AND EXTENT: Eastern Nevada. These soils are not extensive. MLRA 28A.

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

SERIES ESTABLISHED: White Pine County, Great Basin National Park, Nevada, 2009. The name comes from a nearby ridge.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Organic soil material - The zone from the soil surface to 3 cm (Oi horizon).
Ochric epipedon - The zone from the soil surface to 71 cm (Oi, A1, A2, E1, and E2 horizons).
Albic horizon - The zone from 15 to 71 cm (E1 and E2 horizons).
Cambic horizon - The zone from 15 to 43 cm (E1 horizon).
Particle-size control section - The zone from 28 to 103 cm (lower part of the E1 horizon, E2 and C1 horizons).

The revision of December 2006 updated the taxonomic class from Xeric Eutrocryepts based on the tenth edition of the Keys to Soil Taxonomy, 2006.

The revision of March 2001 updated the taxonomic classification from Typic Cryorthents, adjusts all horizon depths for the Oi horizon as the soil surface, and verified the presence of both albic and cambic horizons.

---

National Cooperative Soil Survey
U.S.A.