LOCATION ZYGORE OR+WA
Established Series
Rev. GLG/JGM/KMS
02/2025
ZYGORE SERIES
Landscape--northwestern Middle Cascade glaciated mountains
Landform--mountain slopes, canyon side slopes, broad ridgetops, ridges, glacial-valley walls
Slope--5 to 90 percent
Parent material--colluvium and till derived from basalt and andesite 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 loam, forested
Oi--0 to 8 cm; slightly decomposed needles, twigs, leaves, and cones
A1--8 to 23 cm; gravelly 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 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
Bw--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
BC--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
C--94 to 150 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--6 to 8 degrees C
Hue--10YR, 7.5YR
Fine-earth texture--loam, silt loam
Clay content--8 to 18 percent
Thickness of umbric epipedon--25 to 50 cm
Properties of layers meeting andic subgroup criteria
*1/3-bar bulk density--0.70 to 1.0 g/cm3
*Phosphate retention--50 to 100 percent
*Ammonium oxalate Al plus 1/2 Fe--1 to 2 percent
*Volcanic glass content in 0.02 to 2.0-mm fraction--5 to 20 percent
*Thickness--18 to 50 cm
Oi horizon
*Thickness--0 to 8 cm
A horizons
*Value--2 to 3 moist, 4 or 5 dry
*Chroma--2 or 3 moist or dry
*Total fragment content--15 to 35 percent
*Gravel content--5 to 30 percent
*Cobble content--0 to 20 percent
*Reaction--pH 5.1 to 6.0
*Thickness--18 to 50 cm
Bw horizon
*Value--3 or 4 moist, 4 to 6 dry
*Chroma--2 or 3 moist or dry
*Total fragment content--35 to 60 percent
*Gravel content--10 to 30 percent
*Cobble content--5 to 35 percent
*Stone content--0 to 5 percent
*Reaction--pH 5.1 to 6.5
*Thickness--15 to 45 cm
BC and C horizons
*Value--3 or 4 moist, 4 to 6 dry
*Chroma--3 to 6 moist or dry
*Total fragment content--35 to 70 percent
*Gravel content--10 to 35 percent
*Cobble content--10 to 40 percent
*Stone content--0 to 5 percent
*Reaction--pH 4.5 to 6.5
COMPETING SERIES:
Dougan--50 to 100 cm deep to lithic contact
Fernwood--50 to 100 cm deep to lithic contact
Luckyboy--50 to 100 cm deep to lithic contact
Illahee--averages greater than 18 percent clay in the particle-size control section
GEOGRAPHIC SETTING:
Elevation--450 to 1200 m
Climate--cool, wet winters; warm, dry summers
Mean annual precipitation--1700 to 2700 mm
Mean annual air temperature--5 to 7 degrees C
Frost-free period--30 to 150 days
GEOGRAPHICALLY ASSOCIATED SOILS:
Aschoff--mesic soil temperature regime; located on mountain slopes and colluvial aprons
Bull Run--mesic soil temperature regime and contains less than 15 percent rock fragments; located on hillslopes in mountain valleys
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage class--well drained
Saturation in normal years--none
Flooding--none
Ponding--none
Saturated hydraulic conductivity (Ksat)--moderately high or 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, western swordfern, redwood-sorrel, forbs
DISTRIBUTION AND EXTENT: Cascade Mountains in northwestern Oregon and southwestern Washington; MLRA 3; moderate extent
SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Multnomah County, Oregon; 1977
REMARKS:
Diagnostic horizons and other features in this pedon
*Particle-size control section--zone from 33 to 108 cm
*Umbric epipedon--zone from 8 to 56 cm
*Andic subgroup feature--zone from 8 to 33 cm
*Volcanic glass--zone from 8 to 33 cm
09/2023--laboratory data for geographically associated soils supports andic subgroup criteria in the epipedon. All mineral horizons fall short of andic soil property criteria.
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.
National Cooperative Soil Survey
U.S.A.