LOCATION HEMCROSS OREstablished Series
TAXONOMIC CLASS: Medial, ferrihydritic, mesic Alic Hapludands
TYPICAL PEDON: Hemcross medial silt loam, woodland. (Colors are for moist soil unless otherwise noted.)
0i--0 inches to 2; leaves, needles, moss, roots, twigs.
A1--2 to 9 inches; dark brown (7.5YR 3/2) medial silt loam, brown (10YR 5/3) dry; moderate very fine granular structure; slightly hard, very friable, slightly sticky and nonplastic; weakly smeary; many fine and medium roots; many very fine irregular pores; 10 percent gravel; strongly acid (pH 5.2); gradual smooth boundary.
A2--9 to 19 inches; dark brown (7.5YR 3/3) medial silt loam, brown (10YR 5/3) dry; moderate fine granular and very fine subangular blocky structure; slightly hard, very friable, slightly sticky and nonplastic; weakly smeary; many fine and medium roots; many very fine irregular pores; 10 percent gravel; strongly acid (pH 5.2); clear wavy boundary. (combined A horizon is 8 to 20 inches thick)
Bw1--19 to 34 inches; brown (7.5YR 4/4) medial silt loam, light yellowish brown (10YR 6/4) dry; moderate very fine and fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; weakly smeary; common fine and medium roots; many very fine tubular pores; 5 percent gravel; very strongly acid (pH 4.6); gradual wavy boundary.
Bw2--34 to 48 inches; dark yellowish brown (10YR 4/4) medial silt loam, very pale brown (10YR 7/4) dry; moderate medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; weakly smeary; few fine roots; many very fine tubular pores; 5 percent gravel; very strongly acid (pH 4.8); clear wavy boundary. (combined Bw horizon is 24 to 49 inches thick)
2BC--48 to 62 inches; dark yellowish brown (10YR 4/4) very gravelly medial loam, very pale brown (10YR 7/4) dry; weak fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; few fine roots; many very fine tubular pores; 35 percent gravel, 10 percent cobbles; very strongly acid (pH 4.6).
TYPE LOCATION: Clatsop County, Oregon; 200 feet above a spur road west of Nettle Creek Road, SE1/4 NW1/4 section 30, T. 5 N., R. 6 W., W. M.; Sager Creek, OR USGS 7.5 minute quadrangle; NAD 1927
RANGE IN CHARACTERISTICS: The soil is usually moist but is dry for a short period of less than 45 consecutive days between depths of 4 to 12 inches in the four month period following the summer solstice in most years. The mean annual soil temperature is 47 to 55 degrees F. The particle-size control section has a clay content (field estimate) of 18 to 30 percent and a moist bulk density of 0.75 to 0.90 g/cubic centimeter. It has 5 to 20 percent total rock fragments and 0 to 30 percent pararock fragments. It has greater than 85 percent phosphate retention, 2.0 to 4.0 percent acid-oxalate extractable aluminum plus one-half iron, 2.0 to 15 cmol/kg of KCL-extractable aluminum, and 15 to 30 percent 15-bar moisture (air dried). It is weakly or moderately smeary. The umbric epipedon is 10 to 20 inches thick. The depth to bedrock is more than 60 inches. Reaction is strongly or very strongly acid.
The A horizon has hue of 5YR, 7.5YR, or 10YR, value of 2 or 3 moist, 4 or 5 dry and chroma of 2 or 3 moist, 2 to 4 dry. Texture is medial silt loam or medial loam with 15 to 25 percent clay by field estimate. It has 0 to 15 percent gravel and 0 to 20 percent paragravel. It has 8 to 12 percent organic matter.
An AB horizon is present in some pedons and has color and texture similar to the A horizon.
The Bw horizon has hue of 10YR, 7.5YR, or 5YR, value of 3 or 4 moist, 5 to 7 dry and chroma of 4 to 6 moist and dry. Texture is medial silt loam, medial loam, medial clay loam, or medial silty clay loam with 18 to 35 percent clay by field estimate. It has 0 to 30 percent gravel, 0 to 5 percent cobbles, 0 to 35 percent paragravel and 0 to 10 percent paracobbles.
The 2BC horizon, when present, has hue of 10YR or 7.5YR, value of 4 or 5 moist, 5 to 7 dry and chroma of 4 to 6 moist and dry. Texture is very gravelly medial loam with 15 to 25 percent clay content by field estimate. It has 30 to 50 percent gravel and 0 to 10 percent cobbles.
COMPETING SERIES: These are the Anunde (OR), Belle (WA), Tolke (OR), and Wadell (WA) series.
Anunde soils - have an ochric epipedon, 12 to 27 percent clay in the pscs
Belle soils - have an ochric epipedon; lack a 2BC horizon with 30 to 50 percent rounded gravel; derived from alluvium
Tolke soils - have ochric epipedons; derived from colluvium from tuffaceous sedimentary bedrock
Wadell soils - 40 to 60 inches to 2C horizon with stratified textures; derived from gravelly glacial sediments
GEOGRAPHIC SETTING: Hemcross soils occur on summits, foot slopes, and toe slopes of mountains. Elevations are 200 to 2,200 feet. Slopes are 3 to 90 percent. The soils formed in loamy colluvium and residuum derived from basalt or coarse-grained igneous rock. The climate is characterized by warm wet winters and hot moist summers. The mean annual precipitation is 60 to 120 inches. The mean annual air temperature is 45 to 53 degrees F. The frost-free period is 100 to 220 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Formader, Harslow, Kilchis, and Klistan soils. These soils occur on mountains. Formader soils are 20 to 40 inches deep to bedrock and have a strongly contrasting particle-size class (medial over loamy). Harslow soils are 20 to 40 inches deep to bedrock and have more than 35 percent rock fragments in the particle-size control section. Kilchis soils are 10 to 20 inches deep to a lithic contact. Klistan soils have more than 35 percent rock fragments in the particle-size control section.
DRAINAGE AND PERMEABILITY: Well drained; moderate permeability.
USE AND VEGETATION: These soils are used for timber production, recreation, wildlife habitat, and watersheds. Native vegetation is Douglas fir, western hemlock, red alder, vine maple, western swordfern, salal, red huckleberry, cascade Oregongrape, and western brackenfern.
DISTRIBUTION AND EXTENT: Coast Range Mountains in Oregon; MLRA 1. The soils are of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Clatsop County, Oregon, 1984.
REMARKS:Diagnostic horizons and features recognized in this pedon are:
Umbric epipedon - from the soil surface to a depth of 19 inches (A1 and A2 horizons).
Cambic horizon - from 19 to 48 inches (Bw1 and Bw2 horizons).
Particle-size control section - from 2 to 42 inches
Andic soil properties - the zone from 2 to 48 inches having andic properties and based on lab data from similar soils. Below a depth of approximately 48 inches, andic soil properties are absent primarily due to reduced organic matter and higher bulk density.
Classification revised 8/97 by adding ferrihydritic mineralogy.
Depth to diagnostic horizons and features are measured from the top of the first mineral layer.
ADDITIONAL DATA: Reference samples collected and analysis run by O.S.U. and the NSSL; when samples were collected, the soil was mapped Hembre. Lab reference sample #s 84OR007003, 91OR067008, 92OR057100, and 93OR057010, from NSSL, Lincoln, NE.