LOCATION ZYGORE                  OR+WA

Established Series
Rev. GLG/JGM/KMS
01/2017

ZYGORE SERIES

Landscape--western Cascade Mountains
Landform--mountain slopes, broad ridgetops and canyons of mountains, ridges, glacial-valley walls
Slope--5 to 90 percent
Parent material--colluvium and outwash derived from hard extrusive igneous rock mixed with volcanic ash in upper part
Mean annual precipitation--2200 mm
Mean annual air temperature--about 6 degrees C
Depth class--very deep
Drainage class--well drained
Soil moisture regime--udic
Soil temperature regime--frigid
Soil moisture subclass--typic

TAXONOMIC CLASS: Loamy-skeletal, isotic, frigid Andic Humudepts

TYPICAL PEDON: Zygore gravelly medial loam, forested

Oi--0 to 8 cm; slightly decomposed needles, twigs, leaves, and cones

A1--8 to 23 cm; gravelly medial loam, brown (7.5YR 4/2) dry, dark brown (7.5YR 3/2) moist; moderate fine and very fine granular structure; slightly hard, friable, slightly sticky and slightly plastic; weakly smeary; many very fine, fine, and medium roots; many very fine and fine irregular pores; 15 percent gravel and 5 percent cobbles; 10 percent 2- to 10-mm concretions; moderately acid (pH 5.9); clear wavy boundary

A2--23 to 33 cm; gravelly medial loam, brown (7.5YR 4/3) dry, dark brown (7.5YR 3/2) moist; moderate fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; weakly smeary; many very fine and fine roots; many very fine tubular pores; 15 percent gravel and 5 percent cobbles; 10 percent 2- to 10-mm concretions; moderately acid (pH 5.8); clear wavy boundary

2Bw--33 to 56 cm; very cobbly loam, brown (7.5YR 4/4) dry, dark brown (7.5YR 3/3) moist; moderate fine and very fine subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; common very fine roots; many very fine tubular pores; 15 percent cobbles, 15 percent gravel, and 5 percent stones; 10 percent 2- to 10-mm concretions; moderately acid (pH 6.0); gradual wavy boundary

2BC--56 to 94 cm; very cobbly loam, brown (7.5YR 5/4) dry, brown (7.5YR 4/4) moist; weak medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine roots; many very fine tubular pores; 25 percent cobbles, 15 percent gravel, and 5 percent stones; slightly acid (pH 6.2); gradual wavy boundary

2C--94 to 160 cm; extremely cobbly loam, brown (7.5YR 5/4) dry, brown (7.5YR 4/4) moist; massive; hard, friable, slightly sticky and slightly plastic; common very fine and fine roots; many very fine tubular pores; 35 percent cobbles, 25 percent gravel, and 5 percent stones; slightly acid (pH 6.2)

TYPE LOCATION: Multnomah County, Oregon, about 0.5 km north of Larch Mountain Road; in the SE1/4SW1/4SE1/4 of section 34, T. 1 N., R. 5 E.; latitude 45.5195, longitude -122.173, datum WGS 84 (coordinates estimated from PLSS details)

RANGE IN CHARACTERISTICS:
Dry days--less than 45 consecutive days in all parts following summer solstice
Mean annual soil temperature--5 to 8 degrees C
Reaction--5.1 to 6.5 throughout all mineral horizons
Thickness of umbric epipedon--25 to 50 cm (below mineral soil surface)
Thickness of andic soil properties--18 to 34 cm (below mineral soil surface)

Estimated properties of layers with andic soil properties
*1/3-bar bulk density--0.70 to 0.90 g/cm3
*Phosphate retention--greater than 85 percent
*Ammonium oxalate extractable Al + Fe--1 to 3 percent
*15-bar water retention--30 to 70 percent (undried samples), greater than 15 percent (dried samples)
*0.02- to 2.0-mm fraction--greater than 30 percent
*Volcanic glass content in 0.02- to 2.0-mm fraction--5 to 30 percent

Particle-size control section
*Clay content--8 to 18 percent
*Total fragment content--35 to 70 percent

O horizon
*Thickness--1 to 8 cm

A horizon
*Hue--10YR, 7.5YR
*Value--2 or 3 moist, 4 or 5 dry
*Chroma--2 or 3 moist or dry
*Fine-earth texture--medial loam, medial silt loam
*Clay content--10 to 18 percent
*Sand content--30 to 50 percent
*Total fragment content--15 to 35 percent
*Gravel content--5 to 20 percent
*Cobble content--0 to 20 percent
*Thickness--18 to 36 cm

2Bw horizon
*Hue--10YR, 7.5YR
*Value--3 or 4 moist, 4 to 6 dry
*Chroma--2 or 3 moist or dry
*Fine-earth texture--loam, silt loam
*Clay content--10 to 18 percent
*Sand content--30 to 50 percent
*Total fragment content--35 to 60 percent
*Gravel content--10 to 30 percent
*Cobble content--5 to 40 percent
*Stone content--0 to 5 percent
*Thickness--15 to 45 cm

2BC and 2C horizons
*Hue--10YR, 7.5YR
*Value--3 or 4 moist, 4 to 6 dry
*Chroma--3 to 6 moist or dry
*Fine-earth texture--loam, silt loam
*Clay content--10 to 18 percent
*Sand content--35 to 50 percent
*Total fragment content--35 to 70 percent
*Gravel content--10 to 30 percent
*Cobble content--10 to 40 percent
*Stone content--0 to 5 percent

COMPETING SERIES:
Cadenza--greater than 18 percent clay in particle-size control section
Dougan, Fernwood, Luckyboy--50 to 100 cm deep to lithic bedrock

GEOGRAPHIC SETTING:
Elevation--450 to 1200 m
Climate--warm, moist summers; cool, wet winters
Mean annual precipitation--1750 to 2550 mm
Mean annual air temperature--5 to 8 degrees C
Frost-free period--30 to 120 days

GEOGRAPHICALLY ASSOCIATED SOILS:
Aschoff--mesic soil temperature regime
Bull Run--mesic soil temperature regime; less than 35 percent rock fragments throughout

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage class--well drained
Saturation in normal years--none
Flooding--none
Ponding--none
Saturated hydraulic conductivity (Ksat)--moderately high

USE AND VEGETATION:
Use--timber production, recreation, wildlife habitat
Potential natural vegetation--western hemlock, Douglas-fir, grand fir, red alder, western redcedar, vine maple, red huckleberry, salal, swordfern, Oregon oxalis, forbs

DISTRIBUTION AND EXTENT: Cascade Mountains in northwestern Oregon and southwestern Washington; MLRAs 3 and 6; moderate extent

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon

SERIES ESTABLISHED: Multnomah County, Oregon; 1977

REMARKS:
Diagnostic horizons and other features recognized in this pedon
*Umbric epipedon--zone from 8 to 56 cm
*Particle-size control section--zone from 33 to 108 cm
*Andic soil properties--zone from 8 to 33 cm
*Volcanic glass--zone from 8 to 33 cm

6/1998--Additional data on andic properties needed to confirm classification of the andic subgroup or Andisol order. Classification should be similar to the mesic counterpart Aschoff series and the frigid, moderately deep Dougan series.

8/2016--Layers with andic soil properties assumed to meet criteria 2 (no ash required) in the 12th edition of Keys to Soil Taxonomy. It is also assumed that enough ash is present for those layers to meet criteria 3. Additional lab data is needed to confirm the degree of ash influence

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National Cooperative Soil Survey
U.S.A.