LOCATION MOUNTZION WAEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, active, mesic Typic Palehumults
TYPICAL PEDON: Mountzion clay loam, 15 to 30 percent slopes. (Colors are for moist soil unless otherwise stated.)
A--0 to 5 inches; dark brown (7.5YR 3/2) clay loam, dark brown (7.5YR 4/4) dry; moderate fine granular structure; slightly hard, very friable, slightly sticky and slightly plastic; many very fine and fine roots and common medium roots; many fine irregular pores; 5 percent concretions; moderately acid (pH 5.8); clear wavy boundary. (4 to 6 inches thick)
AB--5 to 17 inches; dark brown (7.5YR 3/3 clay loam, dark brown (7.5YR 4/4) dry; moderate fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine, fine, and medium roots; common fine tubular pores; 5 percent soft basalt pebbles; moderately acid (pH 5.8); clear wavy boundary. (6 to 14 inches thick)
Bt1--17 to 35 inches; dark reddish brown (5YR 3/4) silty clay loam, reddish brown (5YR 4/4) dry; moderate fine and medium subangular blocky structure; hard, friable, sticky and plastic; common fine and medium roots and few coarse roots; common very fine and fine tubular pores; common moderately thick clay films on faces of peds and in some pores; strongly acid (pH 5.2); gradual wavy boundary. (10 to 20 inches thick)
Bt2--35 to 47 inches; dark reddish brown (5YR 3/4) silty clay loam, yellowish red (5YR 4/6) dry; moderate fine and medium subangular blocky structure; hard, friable, sticky and plastic; common fine and medium roots; common fine tubular pores; many moderately thick clay films on faces of peds and in pores; strongly acid (pH 5.2); gradual wavy boundary. (9 to 15 inches thick)
Bt3--47 to 60 inches; dark brown (7.5YR 4/4) clay loam, strong brown (7.5YR 5/6) dry; moderate fine and medium subangular blocky structure; hard, friable, slightly sticky and slightly plastic; few fine and medium roots; few fine tubular pores; few thin clay films on faces of peds; 10 percent pebbles; strongly acid (pH 5.2).
TYPE LOCATION: Skamania County, Washington, about 3 miles northeast of Stevenson; 1,300 feet south and 1,000 feet west of the northeast corner of sec. 24, T.3N., R.7E.
RANGE IN CHARACTERISTICS: The mean annual soil temperature is 49 to 54 degrees F. The particle-size control section is 28 to 35 percent clay. Depth to bedrock is 60 inches or more.
The A and AB horizons have hue of 7.5YR or 5YR, value of 2 or 3 moist, 3 or 4 dry, and chroma of 2 or 3 moist and 2 to 4 when dry. They have 0 to 10 percent pebbles and 0 to 15 percent concretions that are 2 to 5 millimeters in diameter. Reaction is strongly acid or moderately acid.
The Bt horizon has hue of 7.5YR or 5YR, value of 3 or 4 when moist and 4 or 5 when dry, and chroma of 4 to 6 when dry. It average 5 to 20 percent pebbles. The horizon is clay loam or silty clay loam. Reaction is very strongly acid or strongly acid.
COMPETING SERIES: There are no competing series. Similar series in other families are Asta, Baumgard, Buckpeak, and Centralia Olyic series. Asta and Baumgard soils have Andic soil properties in the upper part of the soil profile. Buckpeak and Centralia soils have a xeric moisture regime.
GEOGRAPHIC SETTING: The Mountzion soils are on back slopes and footslopes of mountains at elevations of 600 to 2,000 feet. Slopes are 2 to 65 percent. These soils formed in residuum and colluvium dominantly from basalt. The climate is characterized by warm, dry summers and cool, wet winter. The average annual precipitation is 60 to 90 inches. The mean January temperature is about 36 degrees F, The mean July temperature is about 62 degrees F, and the mean annual temperature is about 49 degrees F. The frost-free season is 130 to 150 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Aschoff and St. Martin soils. Aschoff soils have a skeletal cambic horizon. St. Martin soils have a fine textured cambic horizon and a mollic epipedon.
DRAINAGE AND PERMEABILITY: Well drained; slow to rapid runoff; moderate permeability.
USE AND VEGETATION: Used mainly for timber production. Some is used for hayland, pasture and homesites. Native vegetation is Douglas-fir, grand fir, red alder, western hemlock, and bigleaf maple, with an understory of vine maple, Oregongrape, western swordfern, common snowberry, red huckleberry, Pacific dogwood, western hazel, and thimbleberry.
DISTRIBUTION AND EXTENT: The west slopes of the Cascade Mountains in southwestern Washington. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Skamania County, Washington, 1988.
REMARKS: Diagnostic horizons and features recognized in this pedon are an umbric epipedon from the mineral surface to 17 inches and an argillic horizon from 17 to 60 inches or more, and does not decrease in clay content within 60 inches. These soils were correlated as very deep phase of Olyic series in the correlation of the soils of Skamania County, Washington in 1987. The Olyic series has bedrock within 60 inches of the surface and is Haplohumults. An amendment to Soil Taxonomy signed in June 1988 made the deep phase of Olyic soils Palehumults.
This draft reflects a change in classification only. CEC activity class has been added to the current classification.