LOCATION OPALLAKE                OR

Tentative Series
DCR/JGM/EED
01/2018

OPALLAKE SERIES

Landscape--western Cascade Mountains
Landform--drainageways of cirque floors; drainageways of U-shaped valleys
Slope--0 to 15 percent
Parent material--alluvium and colluvium derived from andesite mixed with volcanic ash in the upper part
Mean annual precipitation--about 2600 mm
Mean annual air temperature--about 6 degrees C
Depth class--very deep
Drainage class--moderately well drained
Soil moisture regime--udic
Soil temperature regime--cryic
Soil moisture subclass--oxyaquic

TAXONOMIC CLASS: Medial over loamy-skeletal, amorphic over isotic Pachic Fulvicryands

TYPICAL PEDON: Opallake medial sandy loam on a 3-percent slope at an elevation of 1067 meters (The soil was moist when described on August 31, 2015.)

Oa--0 to 3 cm; slightly decomposed plant material; abrupt wavy boundary

A1--3 to 48 cm; medial sandy loam, dark brown (10YR 3/3) dry, very dark brown (7.5YR 2.5/2) moist; weak coarse subangular blocky structure; moderately hard, very friable, nonsticky and nonplastic; many very fine and medium and common fine, coarse, and very coarse roots; many very fine and common fine tubular pores; 3 percent gravel and 4 percent weakly cemented wood fragments; very strongly acid (pH 4.8); abrupt wavy boundary

A2--48 to 60 cm; medial loam, brown (10YR 4/3) dry, very dark grayish brown (10YR 3/2) moist; weak coarse subangular blocky structure; slightly hard, very friable, nonsticky and nonplastic; common very fine and medium and few fine roots; many very fine tubular pores; 5 percent gravel; strongly acid (pH 5.2); clear wavy boundary

A3--60 to 80 cm; gravelly medial sandy loam, brown (10YR 4/3) dry, very dark grayish brown (10YR 3/2) moist; weak medium subangular blocky structure; slightly hard, very friable, nonsticky and nonplastic; common very fine and few fine and medium roots; many very fine tubular pores; 28 percent gravel; strongly acid (pH 5.2); clear smooth boundary

2C1--80 to 102 cm; very gravelly sandy loam, brown (10YR 4/3) dry, very dark grayish brown (10YR 3/2) moist; massive; soft, very friable, nonsticky and nonplastic; few very fine roots; many very fine irregular pores; 50 percent gravel and 1 percent cobbles; strongly acid (pH 5.2); gradual smooth boundary

2C2--102 to 150 cm; extremely gravelly sandy loam, brown (10YR 4/3) dry, very dark grayish brown (10YR 3/2) moist; massive; soft, very friable, nonsticky and nonplastic; few very fine roots; many very fine irregular pores; 65 percent gravel and 3 percent cobbles; strongly acid (pH 5.4)

TYPE LOCATION: Marion County, Oregon, 8.6 km northwest of Detroit; 360 m north and 250 m east of the southwest corner of section 17, T. 9 S., R. 5 E.; latitude 44.7885700, longitude -122.2316950, datum WGS 84 (coordinates determined with a GPS)

RANGE IN CHARACTERISTICS:
Soil moisture control section--dry less than 15 consecutive days
Mean annual soil temperature--4 to 6 degrees C
Thickness of umbric epipedon--50 to 80 cm
Reaction--4.5 to 5.5 throughout all mineral horizons
Thickness of andic soil properties--50 to 80 cm

Mineral horizons with andic soil properties
*1/3-bar bulk density--0.60 to 0.90 g/cm3
*Phosphate retention--greater than 85 percent
*Ammonium oxalate extractable Al + Fe--2 to 4 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
*Melanic index--greater than 1.7

Particle-size control section (medial part)
*Clay content--10 to 18 percent
*Total fragment content--0 to 20 percent

Particle-size control section (loamy-skeletal part)
*Clay content--5 to 12 percent
*Total fragment content--35 to 75 percent

O horizon
Thickness--1 to 5 cm

A1 and A2 horizons
Hue--7.5YR, 10YR
Value--2 to 3 moist, 3 or 4 dry
Chroma--1 or 2 moist, 2 or 3 dry
Fine-earth texture--medial sandy loam, medial loam
Clay content--10 to 18 percent
Sand content--40 to 60 percent
Total fragment content--0 to 15 percent
Gravel content--0 to 15 percent
Wood larger than 20 mm--0 to 15 percent
Organic matter content--12 to 20 percent
Thickness--30 to 60 cm

A3 horizon
Value--2 or 3 moist, 3 to 5 dry
Chroma--2 or 3 moist or dry
Fine-earth texture--medial sandy loam, medial loam
Clay content--10 to 18 percent
Sand content--40 to 60 percent
Total fragment content--5 to 30 percent
Gravel content--5 to 30 percent
Cobble content--0 to 5 percent
Stone content--0 to 5 percent
Organic matter content--8 to 12 percent
Thickness--15 to 30 cm

2C horizon
Value--3 or 4 moist, 5 or 6 dry
Chroma--2 or 3 moist or dry
Fine-earth texture--sandy loam, coarse sandy loam
Clay content--5 to 12 percent
Sand content--60 to 75 percent
Total fragment content--35 to 75 percent
Gravel content--35 to 70 percent
Cobble content--0 to 15 percent
Stone content--0 to 5 percent
Organic matter content--1 to 3 percent

COMPETING SERIES: None

GEOGRAPHIC SETTING:
Elevation--1100 to 1500 m
Climate--cool, dry summers; cold, wet winters
Mean annual precipitation--2300 to 2900 mm
Mean annual air temperature--5 to 7 degrees C
Frost-free period--60 to 90 days
Continuous snow cover--December through May

GEOGRAPHICALLY ASSOCIATED SOILS:
Talapus-greater than 35 percent coarse fragments in particle-size control section; andic soil properties greater than 150 cm thick; on mountains and cirque floors
Kinzel--umbric epipedon 25 to 45 cm thick; on mountain slopes, broad ridgetops of mountains, side slopes of canyons in mountains, and colluvial aprons in U-shaped valleys
Marten--spodic horizon; in convex positions on glacially influenced structural benches and cirque floors
Thader--spodic horizon; 50 to 100 cm to lithic contact; on glacial-valley walls, mountain slopes, and ridges
Battleax--less than 6 percent organic carbon in umbric epipedon; on mountain slopes and glacial-valley walls

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage class--moderately well drained
Saturation in normal years--endosaturated below a depth of 50 to 100 cm in June and below a depth of 100 to 200 cm in July through October
Flooding--rare
Ponding--none
Saturated hydraulic conductivity (Ksat)--high in upper part, very high in lower part

USE AND VEGETATION:
Use--watershed, recreation, wildlife habitat
Potential natural vegetation--Pacific silver fir, salmonberry, mountain alder, devilsclub, youth on age, starry false lily of the valley

DISTRIBUTION AND EXTENT: Central western Cascade Mountains, Oregon; MLRA 3; small extent

SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: Portland, Oregon

SERIES PROPOSED: Willamette National Forest, Linn County, Oregon; name from Opal Lake

REMARKS:
Diagnostic horizons and other features recognized in this pedon
*Particle-size control section--zone from 3 to 103 cm
*Umbric epipedon--zone from 3 to 80 cm
*Andic soil properties--zone from 2 to 80 cm
*Volcanic glass--zone from 3 to 80 cm
*Depth to lithologic discontinuity--80 cm
*Strongly contrasting particle-size classes--medial in zone from 3 to 80 cm; loamy-skeletal in zone from 80 to 150 cm

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National Cooperative Soil Survey
U.S.A.