LOCATION PERGRIN CO
Established Series
Rev. JR/GB/KLS
08/2022
PERGRIN SERIES
The Pergrin series consists of moderately deep, well drained soils that formed in colluvium and residuum derived mainly from granite, igneous volcanic materials, and sandstone. This soil is on mountain backslopes and ridges. Slope ranges from 10 to 60 percent. Mean annual precipitation is 640 mm and the mean annual air temperature is 3 degrees C.
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive Ustic Haplocryepts
TYPICAL PEDON: Pergrin gravelly sandy loam, on a northeast aspect of 10 percent slope, lodgepole pine at 2875 meters. (Colors are for dry soil unless otherwise noted.)
Oe--0 to 3 cm; intermediately decomposed coniferous leaf litter.
E--3 to 26 cm; light gray (10YR 7/2) gravelly sandy loam, brown (10YR 4/3) moist; single grain; loose, nonsticky, nonplastic; common fine roots; 20 percent pebbles, 5 percent cobble; slightly acid; clear smooth boundary. (15 to 30 cm thick)
Bw--26 to 46 cm; light yellowish brown (10YR 6/4) very gravelly sandy loam, yellowish brown (10YR 5/6) moist; single grain; loose, nonsticky, nonplastic; few fine roots; 35 percent pebbles, 5 percent cobble; slightly acid; clear smooth boundary. (20 to 35 cm thick)
C--46 to 61 cm; light yellowish brown (10YR 6/4) very gravelly loamy sand, dark yellowish brown (10YR 4/6) moist; single grain; loose, nonsticky, nonplastic; few fine roots; 40 percent pebbles, 5 percent cobble; neutral; abrupt irregular boundary. (15 to 35 cm thick)
Cr--61 to 81 cm; weathering granite grus.
R--81 cm; hard granite.
TYPE LOCATION: Saguache County, Colorado; NW 1/4 SW 1/4, Sec. 20, T. 48 N., R. 8 E. U.S.G.S. Poncha Pass quad.; Lat. 38 degrees, 23 minutes, 48 seconds to 24 minutes, 01 second N.; and Long. 106 degrees, 6 minutes, 46 seconds to 7 minutes, 03 seconds W.
RANGE IN CHARACTERISTICS:
Mean annual soil temperature--2 to 3 degrees C
Mean summer soil temperatures--4 to 6 degrees C
Soil moisture--dry in some part less than one-half the time when the soil temperature is greater than 5 degrees C.
Depth to bedrock--50 to 100 cm
Solum thickness--42 to 100 cm
Soil is noncalcareous throughout.
Particle-size control section:
Clay content--6 to 18 percent
Rock fragment content--35 to 60 percent; predominantly pebble sized, but some pedons may contain up to 50 percent stones
Reaction--pH 5.6 to 7.3
E horizon
Hue--10YR or 7.5YR
Value--6 or 7 dry, 4 through 6 moist
Chroma--2 or 3
Bw horizon
Hue--10YR or 7.5YR
Value--5 through 7 dry, 4 or 5 moist
Chroma--2 through 6
Texture--sandy loam or loam
C horizon
Hue--10YR or 7.5YR
Value--5 or 6 dry, 4 or 5 moist
Chroma--2 through 6
Texture--loamy sand, sandy loam or loam
COMPETING SERIES: These are the
Alpinepeak (ID),
Blackleed (MT),
Ellena (MT),
Elve (MT),
Evaro (MT),
Firada (MT), Frindle (AK),
Garlet (MT),
Gromes (NM),
Hiore (MT), Hughes (AK),
Ketchum (ID),
Longhike (NV),
Losee (UT), Murial (NV),
Nambe (NM),
Poso (ID),
Rubick (MT),
Scout (UT),
Shadow (MT),
Storm (CO),
Taglake (WY),
Targhee (ID), and
Yankeefork (ID) series.
Alpinepeak,
Blackleed,
Elve,
Evaro,
Garlet,
Hiore,
Gromes,
Ketchum,
Losee,
Nambe,
Poso,
Rubick,
Scout,
Shadow,
Storm, and
Taglake soils lack bedrock above 100 cm.
Ellena soils have rock fragments in the particle-size control section that are mostly cobbles.
Firada soil has a consistent k horizon above the bedrock. Frindle soil has a thin mantle of volcanic ash. Hughes soils lack bedrock above 100 cm, but have a 2C horizon of very stony silt loam at 25 to 50 cm.
Longhike soils are dry in all parts of the soil moisture control section for 45 or more consecutive days from late July to October. (Zeric moisture regime.)
Murial soils are 50 to 100 cm deep over calcareous siltstone.
Targhee soils are usually moist when the soil temperature at 50 cm is greater than 5 degrees C.
Yankeefork soils lack bedrock above 100 cm and also have sandy-skeletal materials in the C horizon at 71 to 150 cm.
GEOGRAPHIC SETTING:
Landform--mountain backslopes and ridges
Elevation--2750 to 3525 meters
Slope--10 to 60 percent
Parent material--residuum or colluvium derived dominantly from granite or igneous volcanic materials, and sandstone
Mean annual precipitation--510 to 760 cm
Mean annual air temperature--1 to 3 degrees C
GEOGRAPHICALLY ASSOCIATED SOILS: None listed
DRAINAGE AND PERMEABILITY: Well drained; medium to rapid runoff; moderately rapid permeability
USE AND VEGETATION: This soil is used for timber production, wildlife habitat, recreation, watershed, and summer range. Vegetation is lodgepole pine, subalpine fir, Engelmann spruce, seral aspen, kinnikinnick, common juniper, and scattered grasses and forbs.
DISTRIBUTION AND EXTENT: Pergrin soil is moderately extensive in the mountains of western Colorado; MLRA 48A
SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Rio Grande National Forest (West Part); Saguache County, Colorado
REMARKS: This series name was formerly called Peregrine.
Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon and albic horizon--3 to 26 cm (E horizon)
Cambic horizon--26 to 46 cm (Bw horizon)
Lithic contact--81 cm to bedrock (R horizon)
Pergrin soils have a cryic temperature regime and a udic soil moisture regime bordering on ustic.
Converted to metric, updated formatting, and O horizons were updated to start at zero. 8/2022
National Cooperative Soil Survey
U.S.A.