LOCATION MERSHON OR
Established Series
Rev. RTS/AON
06/2011
MERSHON SERIES
The Meshon series consists of deep, moderately well drained soils that formed in loess and old mixed alluvium. Mershon soils are on high terraces and have slopes of 0 to 30 percent. Mean annual precipitation is about 65 inches and the mean annual temperature is about 51 degrees F.
TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Aquic Humudepts
TYPICAL PEDON: Mershon silt loam, cultivated. (Colors are for moist soil unless otherwise noted.)
Ap--0 to 8 inches; very dark grayish brown (10YR 3/2) silt loam, grayish brown (10YR 5/2) dry; moderate very fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; 2 percent gravel; moderately acid (pH 5.8); clear smooth boundary. (6 to 8 inches thick)
A--8 to 15 inches; very dark grayish brown (10YR 3/2) silt loam, grayish brown (10YR 5/2) dry; moderate very fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine roots; many very fine irregular pores; 2 percent gravel; moderately acid (pH 5.8); clear wavy boundary. (4 to 8 inches thick)
BA--15 to 21 inches; brown (10YR 4/3) silt loam, pale brown (10YR 6/3) dry; moderate very fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine roots; many very fine tubular pores; 2 percent gravel; moderately acid (pH 5.8); gradual wavy boundary. (6 to 8 inches thick)
Bw1--21 to 32 inches; brown (10YR 4/3) silt loam, pale brown (10YR 6/3) dry; few fine light brownish gray (10YR 6/2) redox depletions; moderate fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; few very fine roots; many very fine tubular pores; few fine nodules; 2 percent gravel; moderately acid (pH 5.8); clear wavy boundary. (10 to 16 inches thick)
Bw2--32 to 43 inches; brown (10YR 4/3) silt loam, pale brown (10YR 6/3) dry; few distinct gray (10YR 5/1) redox depletions; moderate fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; few very fine roots; many very fine tubular pores; 2 percent gravel; moderately acid (pH 5.6); clear wavy boundary. (10 to 12 inches thick)
Bt--43 to 56 inches; brown (10YR 4/3) silt loam, pale brown (10YR 6/3) dry; few fine distinct gray (10YR 5/1) redox depletions and streaks; moderate medium and fine subangular blocky structure; hard, firm, slightly sticky and slightly plastic; few faint clay films in pores; few fine black stains; 8 percent gravel and 5 percent cobbles; strongly acid (pH 5.4); clear wavy boundary. (4 to 14 inches thick)
2C--56 to 60 inches; brown (10YR 4/3) loam, pale brown (10YR 6/3) dry; massive; very hard, very firm, slightly sticky and slightly plastic; few very fine roots; many very fine irregular pores; common fine black stains; 10 percent partially weathered gravel and 3 percent partially weathered cobbles; strongly acid (pH 5.4).
TYPE LOCATION: Multnomah County, Oregon; about 300 feet west of Little Page Road; SE1/4 NE1/4 NW1/4 section 2, T.1S., R.4E.
RANGE IN CHARACTERISTICS: The mean annual soil temperature is 51 to 53 degrees F. These soils are dry for less than 45 consecutive days in all parts between depths of 4 and 12 inches during the 4 month period following the summer solstice. The umbric epipedon is 10 to 15 inches thick. Depth to bedrock is more than 60 inches. Depth to the very hard, very firm 2C horizon is 40 to 60 inches.
The A horizon has hue of 10YR or 7.5YR, value of 4 or 5 dry , and chroma of 2 or 3 moist and dry. It is loam or silt loam and has 0 to 10 percent gravel.
The Bw and Bt horizon has hue of 10YR or 7.5YR, value of 3 or 4 moist, and chroma of 3 or 4 moist and dry. Few grey redox depletions are on surfaces of peds below depth of 20 inches. It is loam or silt loam and has 18 to 27 percent clay and less than 15 percent coarser than very fine sand. It has 0 to about 5 percent gravel above depth of 40 inches and increase below this depth.
The 2C horizon has 2 to 15 percent gravel and cobbles.
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: The Mershon soils are on high terraces at elevations of 450 to 1,300 feet. Slopes range from 0 to 30 percent. The soils formed in old mixed alluvium. The mean January temperature ranges from 33 to 35 degrees F.; the mean July temperature ranges from 66 to 68 degrees F.; and the mean annual temperature ranges from 50 to 52 degrees F. The mean annual precipitation is 60 to 70 inches. The frost free season is 165 to 200 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Cazadero soils. Cazadero soils have red clay or silty clay argillic horizons.
DRAINAGE AND PERMEABILITY: Moderately well drained; slow to rapid runoff; moderately slow permeability.
USE AND VEGETATION: Mershon soils are used mainly for berries, small grain, hay, pasture, homesites, wildlife habitat and timber production. Native vegetation is Douglas-fir, red alder, bigleaf maple, vine maple, willow, brachenfern, common snowberry, western hazel, blue elderberry, creambush oceanspray, trailing blackberry, and western red cedar.
DISTRIBUTION AND EXTENT: Multnomah County, Oregon; MLRA 3. The soil is inextensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Multnomah County, Oregon, 1977.
REMARKS: Diagnostic horizons and features include:
Umbric epipedon - from 0 to 15 inches (Ap and A horizons)
Cambic horizon - from 15 to 56 inches
Aquic feature - redox depletions from 21 to 56 inches
National Cooperative Soil Survey
U.S.A.