LOCATION GRENNAN WAEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, isotic, mesic Oxyaquic Glossudalfs
TYPICAL PEDON: Grennan extremely gravelly sandy loam - forestland, on a 33 percent slope with a northerly aspect at an elevation of 1,070 feet in a western hemlock/salal-western swordfern plant association. (When described on November 4, 1993, the soil was moist throughout. Colors are for moist soil unless otherwise stated.)
Oi--0 to 1 inch; slightly decomposed needles, leaves and twigs; abrupt smooth boundary. (0.5 to 1.5 inches thick)
E--1 to 10 inches; olive brown (2.5Y 4/3) extremely gravelly sandy loam, light gray (2.5Y 7/2) dry; weak very fine and fine subangular blocky and weak very fine and fine granular structure; slightly hard, friable, slightly sticky and slightly plastic; many very fine and fine and common medium and coarse roots; many very fine and fine irregular pores; 55 percent gravel, 10 percent cobbles; moderately acid (pH 5.8); clear smooth boundary. (4 to 10 inches thick)
E/Bt1--10 to 19 inches; 80 percent light olive brown (2.5Y 5/3) pale yellow (2.5Y 7/3) dry (E) and 20 percent olive brown (2.5Y 4/3) (Bt) extremely gravelly sandy loam; weak fine, medium, and coarse subangular blocky and weak very fine and fine granular structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine, fine, medium, and coarse roots; common very fine and fine irregular pores; few faint clay films on faces of peds and lining pores; few fine distinct yellowish red (5YR 4/6) irregularly shaped masses of iron accumulation with diffuse boundaries in the matrix; 40 percent gravel, 20 percent cobbles; moderately acid (pH 6.0); clear smooth boundary.
E/Bt2--19 to 31 inches; 80 percent light olive brown (2.5Y 5/3) pale yellow (2.5Y 7/3) dry (E) and 20 percent olive brown (2.5Y 4/4) (Bt) extremely gravelly sandy clay loam; weak fine, medium, and coarse subangular blocky and weak very fine and fine granular structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine and fine and few medium and coarse roots; common very fine and fine tubular and irregular pores; few faint clay films on faces of peds and lining pores; common fine distinct yellowish red (5YR 4/6) irregularly shaped masses of iron accumulation with clear boundaries in the matrix; 30 percent gravel, 20 percent cobbles, 15 percent stones; slightly acid (pH 6.2); clear wavy boundary. (Combined thickness of the E/Bt horizon is 18 to 40 inches.)
Bt1--31 to 46 inches; olive brown (2.5Y 4/3) extremely gravelly sandy clay loam; weak fine, medium, and coarse subangular blocky structure; slightly hard, friable, moderately sticky and slightly plastic; few very fine and fine roots; few very fine and fine tubular and irregular pores; common distinct strong brown (7.5YR 5/6) dry clay films on faces of peds and lining pores; few fine distinct brown (7.5YR 4/4) irregularly shaped masses of iron accumulation with clear boundaries in the matrix; common fine distinct olive brown (2.5Y 4/3) moist and light gray (2.5Y 7/2) dry irregularly shaped iron depletions with diffuse boundaries in the matrix; 40 percent gravel, 20 percent cobbles; slightly acid (pH 6.2); clear wavy boundary.
Bt2--46 to 52 inches; olive brown (2.5Y 4/4) extremely gravelly sandy clay loam; weak fine, medium, and coarse subangular blocky structure; slightly hard, friable, moderately sticky and slightly plastic; few very fine roots; few very fine tubular and irregular pores; common distinct clay films on faces of peds and lining pores; few fine distinct strong brown (7.5YR 4/6) irregularly shaped masses of iron accumulation with clear boundaries in the matrix; few fine and medium distinct light olive brown (2.5Y 5/3) irregularly shaped iron depletions with diffuse boundaries in the matrix; 40 percent gravel, 25 percent cobbles; slightly acid (pH 6.2); clear wavy boundary.
Bt3--52 to 61 inches; olive brown (2.5Y 4/3) extremely gravelly sandy clay loam; weak fine, medium, and coarse subangular blocky structure; slightly hard, friable, moderately sticky and slightly plastic; few very fine tubular and irregular pores; common distinct clay films on faces of peds and lining pores; few fine distinct yellowish red (5YR 4/6) irregularly shaped masses of iron accumulation with clear boundaries in the matrix; common fine and medium distinct light olive brown (2.5Y 5/3) irregularly shaped iron depletions with diffuse boundaries in the matrix; 40 percent gravel, 25 percent cobbles; slightly acid (pH 6.4).
TYPE LOCATION: Clallam County, Washington, about 4 miles north of Mt. Zion, about 2,645 feet east and 1,495 feet south of the northwest corner of Section 25, T. 29 N., R. 3 W. (Latitude 47 degrees, 58 minutes, 53 seconds N., Longitude 123 degrees, 00 minutes, 17 seconds W.)
RANGE IN CHARACTERISTICS: Mean annual soil temperature is 47 to 51 degrees F. These soils are usually moist, and are dry 30 to 45 consecutive days in the soil moisture control section. The particle-size control section has 35 to 75 percent rock fragments by volume and 25 to 35 percent clay. Depth to the glossic horizon and redox features is 4 to 10 inches.
The E horizon has hue of 10YR or 2.5Y moist and dry, value of 6 or 7 dry, and chroma of 2 or 3 dry and moist.
The E/Bt horizon for the E portion has hue of 2.5Y or 5Y moist and dry, value of 4 or 5 moist, 6 or 7 dry and chroma of 2 or 3 moist and dry. The Bt portion has hue of 2.5Y or 10YR moist and dry and chroma of 3 or 4 moist. It is extremely gravelly sandy clay loam, extremely gravelly sandy clay loam, or very gravelly sandy clay loam. Texture of E and Bt material are the same. Reaction is moderately or slightly acid. Albic materials comprise 50 to 85 percent of the horizon.
The Bt horizon has hue of 2.5Y or 5Y moist and dry, value of 6 or 7 dry, 4 or 5 moist and chroma of 3 or 4 moist and 2 or 3 dry. It is extremely gravelly sandy clay loam, very gravelly sandy clay loam, or very gravelly clay loam. Reaction is slightly acid or neutral.
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Grennan soils are on low relief, dissected uplands and have slopes of 5 to 60 percent. The soils formed in residuum and colluvium from proglacial lake deposits and continental glacial till. Elevations are 700 to 1,900 feet. Average annual precipitation ranges from 30 to 40 inches. Average annual temperature is 45 to 49 degrees F. The frost-free season is 170 to 190 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Hardwick and Jimmycomelately soils. Hardwick and Jimmycomelately soils are on low relief, dissected uplands. Hardwick soils are fine textured and Jimmycomelately soils have a xeric moisture regime.
DRAINAGE AND PERMEABILITY: Somewhat poorly drained; moderately slow permeability. Grennan soils have an apparent water table in which the soil is saturated for very brief or brief periods following a storm event. Total cumulative saturation time of the soil is estimated to be less than 30 days. The soils have an apparent zone of saturation between 1.0 and 3.0 feet from November through April; 120 to 180 cumulative days.
USE AND VEGETATION: Timber production, wildlife habitat, recreation, and watershed. Native vegetation is Douglas-fir, western hemlock, western redcedar, salal, western swordfern, Oregon-grape, and red huckleberry.
DISTRIBUTION AND EXTENT: Clallam County, Washington; MLRA 1. Series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Clallam County, Washington, 2000; Olympic National Forest.
REMARKS: Diagnostic horizons and features recognized in this pedon are the following:
Ochric epipedon
Albic horizon - 1 to 10 inches (E horizon)
Glossic horizon - 10 to 31 inches (E/Bt1 and E/Bt2 subhorizons)
Argillic horizon - 19 to 61 inches (E/Bt2, Bt1, Bt2, and Bt3 subhorizons)
Oxyaquic feature - apparent water table is at its highest depth between November through April and is present for 120 to 180 cumulative days.
PSCS - 19 to 39 inches (E/Bt2 and Bt1 subhorizons)
The soils formed in relic proglacial lake deposits in a wetter environment. The presence of the albic materials and redox features in the upper horizons were not formed from present day pedogenesis.
Depth to diagnostic horizons and other features are measured from the top of the first mineral horizon. Based on the color combinations in the glossic horizon some pedons will classify as aquic subgroup and are considered taxadjuncts.