LOCATION SEPARATION              OR

Tentative Series
IRD. DCR/MPR
02/2025

SEPARATION SERIES

Landscape--High Cascade glaciated mountains
Landform--glacial-valley floors, lateral moraines, glaciated mountains , lakebeds
Slope--0 to 55 percent
Parent material--volcanic ash over till mixed with volcanic ash
Mean annual precipitation--2150 mm
Mean annual air temperature--about 5 degrees C
Depth class--moderately deep to densic contact
Drainage class--well drained
Soil moisture regime--udic
Soil temperature regime--cryic
Soil moisture subclass--typic

TAXONOMIC CLASS: Medial, amorphic Typic Haplocryands

TYPICAL PEDON: Separation medial fine sandy loam on a 3-percent, forested slope at an elevation of 1183 m

Oi--0 to 2 cm; slightly decomposed plant material; abrupt smooth boundary

Oe--2 to 4 cm; moderately decomposed plant material; abrupt wavy boundary

A1--4 to 25 cm; medial fine sandy loam, brown (10YR 5/3) dry, dark brown (7.5YR 3/3) moist; weak fine subangular blocky structure; soft, very friable, nonsticky, nonplastic; common very fine through coarse roots; common very fine dendritic tubular pores; 2 percent gravel and 1 percent moderately coherent fine pumice paragravel; moderately acid (pH 5.7); clear wavy boundary

A2--25 to 48 cm; medial fine sandy loam, brown (10YR 5/3) dry, dark brown (7.5YR 3/3) moist; weak medium subangular blocky structure; soft, very friable, nonsticky, nonplastic; common very fine through coarse roots; common very fine dendritic tubular pores; 4 percent gravel and 1 percent moderately coherent fine pumice paragravel; moderately acid (pH 5.7); clear wavy boundary

2Bw1--48 to 70 cm; cobbly medial loam, pale brown (10YR 6/3) dry, brown (7.5YR 4/3) moist; weak medium subangular blocky structure; slightly hard, very friable, nonsticky, nonplastic; common very fine and medium and few fine roots; common very fine dendritic tubular pores; 7 percent gravel, 1 percent moderately coherent fine pumice paragravel, and 10 percent cobbles; moderately acid (pH 6.0); clear wavy boundary

2Bw2--70 to 90 cm; cobbly medial loam, pale brown (10YR 6/3) dry, brown (7.5YR 4/3) moist; weak coarse subangular blocky structure; slightly hard, very friable, nonsticky, nonplastic; few very fine roots; common very fine dendritic tubular pores; 7 percent gravel, 1 percent moderately coherent fine pumice paragravel, and 10 percent cobbles; slightly acid (pH 6.1); abrupt smooth boundary

2Cd--90 to 150 cm; loam, light gray (10YR 7/2) dry, brown (10YR 4/3) moist; massive; very hard, firm, nonsticky, slightly plastic; few very fine roots with horizontal spacing greater than 10 cm; few very fine dendritic tubular pores; 2 percent very pale brown (10YR 7/4), moist, noncoherent silica coats on surfaces along pores; 5 percent gravel and 5 percent cobbles; slightly acid (pH 6.2)

TYPE LOCATION: Lane County, Oregon, about 16 km east of McKenzie Bridge; 290 m west of the northeast corner of section 9, T. 16 S., R. 7 E.; latitude 44.19693, longitude -121.96418, datum WGS 84 (coordinates determined with a GPS)

RANGE IN CHARACTERISTICS:
Mean annual soil temperature--3 to 8 degrees C
Thickness of umbric epipedon--18 to 50 cm
Depth to densic contact--50 to 100 cm below the mineral soil surface
Thickness of andic soil properties--50 to 100 cm

Particle-size control section
*Ammonium oxalate extractable Al plus 1/2 Fe--2 to 6 percent
*Particles 0.02- to 2.0-mm diameter--greater than 30 percent of the fine-earth fraction
*Volcanic glass content in 0.02- to 2.0-mm fraction--30 to 60 percent
*Phosphate retention--85 to 100 percent
*15-bar water retention--at least 15 percent (dried samples)
*1/3-bar bulk density--0.6 to 1.2 g/cm3

O horizons
*Composition--slightly to moderately decomposed plant material
*Combined thickness--0 to 8 cm

A horizons
*Hue--7.5YR, 10YR
*Value--2 or 3 moist, 4 or 5 dry
*Chroma--2 or 3 moist and dry
*Fine-earth texture--medial fine sandy loam, medial loamy fine sand
*Clay content--2 to 10 percent
*Sand content--55 to 80 percent
*Total fragment content--0 to 15 percent
*Gravel content--0 to 15 percent
*Cobble content--0 to 5 percent
*Pumice paragravel content--0 to 5 percent
*Thickness--25 to 50 cm

2Bw horizons
*Hue--7.5YR, 10YR
*Value--3 or 4 moist, 5 or 6 dry
*Chroma--3 or 4 moist and dry
*Fine-earth texture--medial loam, medial fine sandy loam
*Clay content--7 to 18 percent
*Sand content--40 to 60 percent
*Total fragment content--5 to 50 percent
*Gravel content--5 to 15 percent
*Cobble content--0 to 30 percent
*Stone content--0 to 20 percent
*Pumice paragravel content--0 to 5 percent
*1/3-bar bulk density--0.9 to 1.4 g/cm3
*Reaction--pH 5.6 to 6.5
*Thickness--25 to 75 cm

2Cd horizon
*Value--3 to 5 moist, 5 to 7 dry
*Chroma--2 to 4 moist and dry
*Fine-earth texture--loam
*Clay content--7 to 18 percent
*Sand content--35 to 52 percent
*Total fragment content--5 to 35 percent
*Gravel content--0 to 30 percent
*Cobble content--0 to 15 percent
*1/3-bar bulk density--1.8 to 2.0 g/cm3
*Reaction--pH 5.6 to 6.5

COMPETING SERIES:
Cruiser--averages 20 to 30 percent clay in the particle-size control section
Keel--50 to 100 cm to lithic contact
Longbow--umbric epipedon contains more than 10 percent clay in the fine-earth fraction
Soapgrass--umbric epipedon contains more than 10 percent clay in the fine-earth fraction
Molawa--ochric epipedon
Oneonta--thickness of umbric epipedon is greater than 50 cm
Soosap--50 to 100 cm to a paralithic contact

GEOGRAPHIC SETTING:
Elevation--1150 to 2075 m
Climate--cold, wet winters; mild, dry summers
Mean annual precipitation--1800 to 2600 mm
Mean annual air temperature--2 to 7 degrees C
Frost-free period--30 to 105 days

GEOGRAPHICALLY ASSOCIATED SOILS:
Patjens--50 to 100 cm to lithic contact ; located on ice-scoured mountains and ice-scoured glacial-valley walls
Proxy--frigid soil temperature regime; located on glaciated mountains and lateral moraines

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage class--well drained
Saturation in normal years--none within profile
Flooding--none
Ponding--none
Saturated hydraulic conductivity (Ksat)--high or very high in the upper part; moderately low in densic material

USE AND VEGETATION:
Use--watershed, recreation, wildlife habitat, timber production
Potential natural vegetation--mountain hemlock, Pacific silver fir, western white pine, Douglas-fir, grand fir, thinleaf huckleberry, Pacific rhododendron, Cascade barberry, common beargrass, starry false lily of the valley, bride's bonnet; commonly supports a Pacific silver fir-grand fir/starry false Solomon's seal (CFC311) plant association (Field Guide to the Forested Plant Associations of the Westside Central Cascades of Northwest Oregon)

DISTRIBUTION AND EXTENT: High Cascade Mountains, Oregon; MLRA 3; moderate extent

SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: Bozeman, Montana

SERIES PROPOSED: Willamette National Forest, Lane County, Oregon; named for Separation Creek near the type location

REMARKS:
Diagnostic horizons and features in this pedon
*Particle-size control section--zone from 4 to 90 cm
*Umbric epipedon--zone from 4 to 48 cm
*Cambic horizon--zone from 48 to 90 cm
*Depth to densic contact--90 cm
*Densic materials--zone from 90 to 150 cm
*Andic soil properties--zone from 4 to 90 cm
*Volcanic glass--zone from 4 to 90 cm
*Lithologic discontinuity--48 cm

09/2023--all mineral horizons meet criteria #3 for andic soil properties in the 13th edition of Keys to Soil Taxonomy. All pedons have third-bar bulk density low enough to also meet criteria #2 (no ash required) throughout the umbric epipedon, and some pedons meet criteria #2 throughout the profile.

Separation soils occur in areas of till deposition. LiDAR hillshade texture is smooth to lumpy, including arcuate recessional moraines and drumlins oriented parallel to the local drainage basin. Separation soils usually occur down-basin from "rough" LiDAR areas which feature many small (10s to 100s of meters long) roche moutonnees or bedrock knobs.

ADDITIONAL DATA: Type location user pedon ID--2022OR039791

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National Cooperative Soil Survey
U.S.A.