LOCATION CLACKAMAS               OR

Established Series
Rev. AON/JGM/EED
01/2020

CLACKAMAS SERIES

Landscape--Willamette Valley
Landform--stream terraces
Slope--0 to 3 percent
Parent material--alluvium
Mean annual precipitation--about 1300 mm
Mean annual air temperature--about 11 degrees C
Depth class--very deep
Drainage class--somewhat poorly drained
Soil moisture regime--aquic
Soil temperature regime--mesic
Soil moisture subclass--typic

TAXONOMIC CLASS: Fine-loamy, mixed, superactive, mesic Typic Argiaquolls

TYPICAL PEDON: Clackamas gravelly loam under grass

Ap--0 to 15 cm; gravelly loam, dark grayish brown (10YR 4/2) dry, very dark brown (10YR 2/2) moist; moderate medium and fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; many very fine roots; many very fine and fine irregular pores; moderately acid (pH 5.6); abrupt smooth boundary

AB--15 to 38 cm; gravelly loam, dark grayish brown (10YR 4/2) dry, very dark grayish brown (10YR 3/2) moist; moderate medium subangular blocky structure; hard, friable, slightly sticky and slightly plastic; many roots; many very fine and fine tubular pores; 5 percent fine faint black (10YR 2/1) masses of manganese and 5 percent medium prominent reddish brown (5YR 4/4) masses of oxidized iron on surfaces along pores; moderately acid (pH 5.8); clear smooth boundary

Btg--38 to 61 cm; gravelly clay loam, grayish brown (10YR 5/2) dry, very dark gray (10YR 3/1) moist; moderate medium subangular blocky structure; hard, friable, sticky and plastic; many roots; many very fine and fine pores; 2 percent clay films on all faces of peds, 5 percent clay films on surfaces along pores and on rock fragments, and 4 percent organic stains on all faces of peds; 20 percent fine prominent dark reddish brown (2.5YR 3/4) masses of oxidized iron on surfaces along pores; 16 percent gravel and 2 percent cobbles; moderately acid (pH 5.6); abrupt smooth boundary

2Cg--61 to 150 cm; extremely gravelly clay loam, pale brown (10YR 6/3) dry, dark brown (10YR 3/3) moist; massive; very hard, firm, slightly sticky and slightly plastic; few pores; 10 percent medium distinct grayish brown (10YR 5/2) iron depletions in matrix surrounding redoximorphic concentrations and 20 percent medium distinct strong brown (7.5YR 5/6) masses of oxidized iron on surfaces along pores; 70 percent gravel and 10 percent cobbles; strongly acid (pH 5.4)

TYPE LOCATION: Marion County, Oregon, about 0.5 km west of Wirth Lake; about 15 m east of paved road in the NE1/4SE1/4 of section 1, T. 8 S., R. 3 W.; latitude 44.9050713, longitude -122.9935571, datum WGS 84 (coordinates estimated from PLSS details)

RANGE IN CHARACTERISTICS:
Mean annual soil temperature--about 11 to 13 degrees C
Moisture control section--seasonal high water table within 15 to 46 cm of the soil surface during the growing season
Thickness of mollic epipedon--30 to 65 cm
Depth to top of argillic horizon--15 to 46 cm
Depth to aquic conditions--15 to 46 cm
Depth to lithologic discontinuity--50 to 90 cm

Particle-size control section
*Clay content--27 to 35 percent
*Total rock fragment content--5 to 35 percent

Ap horizon
Hue--10YR, 2.5Y
Value--2 or 3 moist, 4 or 5 dry
Chroma--2 or 3 moist or dry
Fine-earth texture--loam, silt loam
Clay content--18 to 27 percent
Sand content--20 to 50 percent
Total rock fragment content--0 to 30 percent
Gravel content--0 to 30 percent
Cobble content--0 to 5 percent
Reaction--5.6 to 6.5
Thickness--13 to 30 cm

AB horizon
Hue--10YR, 2.5Y
Value--2 or 3 moist, 4 or 5 dry
Chroma--2 or 3 moist or dry
Fine-earth texture--loam to silt loam
Clay content--18 to 27 percent
Sand content--20 to 50 percent
Total rock fragment content--0 to 30 percent
Gravel content--0 to 30 percent
Cobble content--0 to 5 percent
Reaction--5.6 to 6.5
Thickness--0 to 33 cm

Btg horizon
Hue--10YR, 2.5Y, 5Y
Value--3 or 4 moist, 5 or 6 dry
Chroma--1 or 2 moist or dry
Fine-earth texture--clay loam, silty clay loam
Clay content--27 to 35 percent
Sand content--15 to 45 percent
Total rock fragment content--5 to 35 percent
Gravel content--5 to 30 percent
Cobble content--0 to 5 percent
Reaction--5.6 to 6.5
Thickness--20 to 38 cm

2Cg horizon
Hue--10YR, 2.5Y, 5Y
Value--3 or 4 moist, 5 or 6 dry
Chroma--1 or 2 moist or dry
Fine-earth texture--clay loam, silty clay loam, loam, silt loam
Clay content--25 to 35 percent
Sand content--15 to 45 percent
Total rock fragment content--55 to 80 percent
Gravel content--50 to 70 percent
Cobble content--5 to 10 percent
Reaction--5.1 to 6.0

COMPETING SERIES:
Barry--18 to 25 percent clay in particle-size control section; 0 to 15 percent coarse fragments in series control section
Brookston--free calcium carbonates; 0 to 11 percent coarse fragments in series control section
Cordova--free calcium carbonates; no coarse fragments in particle-size control section
Forestcity--argillic horizon at a depth of more than 60 cm; less than 10 percent coarse fragments in particle-size control section
Hamel--free calcium carbonates; 2 to 6 percent coarse fragments in particle-size control section
Jameston--free calcium carbonates; 30 to 35 percent clay in particle-size control section
Millgrove--free calcium carbonates; 10 to 40 percent coarse fragments in series control section
Navan--free calcium carbonates; no coarse fragments in particle-size control section
Navunon--100 to 150 cm or more (deep, very deep) to a lithic contact (limestone)
Nosoni--mollic epipedon 60 to 120 cm thick; more than 50 percent sand
Radioville, Rensselaer--free calcium carbonates; 0 to 5 percent gravel in particle-size control section
Tallmadge--free calcium carbonates; 100 to 150 cm (deep) to a lithic contact (limestone, dolostone)
Westland--less than 25 percent clay below argillic horizon; chroma of less than 1 and neutral hue throughout

GEOGRAPHIC SETTING:
Elevation--55 to 215 m
Climate--warm, dry summers; cool, moist winters
Mean annual precipitation--1000 to 1500 mm
Mean annual air temperature--about 10 to 12 degrees C
Mean January air temperature--about 4 degrees C
Mean July air temperature--about 19 degrees C
Frost-free period--165 to 210 days

GEOGRAPHICALLY ASSOCIATED SOILS:
Courtney--poorly drained; fine textural class; in depressions of stream terraces
Salem--sandy-skeletal material within a depth of 100 cm; in similar positions
Coburg--moderately well drained; fine textural class; in similar positions

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage class--somewhat poorly drained
Saturation in normal years--apparent water table at a depth of 15 to 46 cm
Flooding--none
Ponding--none
Saturated hydraulic conductivity--moderately low

USE AND VEGETATION:
Use--production of small grain, commodity crops, pasture, and hay
Potential natural vegetation--Douglas-fir, California hazel, brackenfern, grasses

DISTRIBUTION AND EXTENT: Tributary valleys of the Willamette Valley area in western Oregon; MLRA 2; moderate extent

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

SERIES ESTABLISHED: Soil survey of Clackamas County, Oregon; 1921

REMARKS:
Diagnostic horizons and other features in this pedon
*Particle-size control section--zone from 38 to 61 cm
*Mollic epipedon--zone from the surface to a depth of 61 cm
*Argillic horizon--zone from 38 to 61 cm
*Aquic conditions--zone from 38 to 150 cm
*Depth to lithologic discontinuity--61 cm

The Clackamas soils are on the Winkle geomorphic surface in the Willamette Valley of Oregon.

8/2017--This official series description was updated according to SSR01 Technical Note 11--Content and Format of Official Series Descriptions (revised 12/2015). Most of the changes were in formatting; no major technical changes were made.

ADDITIONAL DATA:
Characterization data--soil survey sample numbers 01OR047003, S2001OR043003, and S2005OR047002; National Soil Survey Laboratory

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National Cooperative Soil Survey
U.S.A.