LOCATION MARCOLA OREstablished Series
TAXONOMIC CLASS: Clayey-skeletal, mixed, superactive, mesic Pachic Ultic Argixerolls
TYPICAL PEDON: Marcola cobbly silty clay loam, cultivated. (Colors are for moist soil unless otherwise noted.)
Ap--0 to 9 inches; very dark brown (10YR 2/2) cobbly silty clay loam, dark grayish brown (10YR 4/2) dry; moderate fine and very fine subangular blocky and moderate fine granular structure; very hard, friable, sticky and plastic; many very fine roots; many very fine tubular and irregular pores; 10 percent gravel and 20 percent cobbles; slightly acid (pH 6.4); abrupt smooth boundary. (5 to 9 inches thick)
AB--9 to 15 inches; very dark brown (10YR 2/2) cobbly silty clay loam, very dark gray (10YR 3/2) dry; moderate medium and fine subangular blocky structure; very hard, friable, sticky and plastic; many very fine roots; many very fine tubular pores; 15 percent gravel and 15 percent cobbles; slightly acid (pH 6.4); clear smooth boundary. (5 to 10 inches thick)
Bt1--15 to 23 inches; dark brown (10YR 3/3) very cobbly clay, dark grayish brown (10YR 4/2) dry; moderate fine subangular blocky structure; very hard, firm, very sticky and very plastic; common very fine roots; many very fine tubular pores; few thin clay films; 20 percent gravel and 35 percent cobbles; neutral (pH 6.6); clear wavy boundary. (6 to 18 inches thick)
Bt2--23 to 33 inches; dark brown (10YR 4/3); extremely cobbly clay, dark grayish brown (10YR 4/2) dry; moderate fine subangular blocky structure; extremely hard, firm, very sticky and very plastic; few very fine roots; many very fine tubular pores; common moderately thick clay films and bridges; 30 percent gravel and 45 percent cobbles; neutral (pH 6.6); clear wavy boundary. (8 to 12 inches thick)
Bt3--33 to 60 inches; multicolored dark grayish brown (10YR 4/2), dark brown (10YR 4/3), and yellowish brown (10YR 5/4) extremely cobbly clay, light brownish gray (10YR 6/2) dry; common distinct light gray (10YR 7/1) and yellowish brown (10YR 5/8) mottles; massive; extremely hard, very firm, very sticky and very plastic; few very fine roots; common very fine tubular pores; common moderately thick clay films in pores; 30 percent gravel and 40 percent cobbles; neutral (pH 6.8).
TYPE LOCATION: Lane County, Oregon; east of Hill Road in the SW1/4 SE1/4 of section 8, T. 17 S., R. 2 W.
RANGE IN CHARACTERISTICS: The mean annual soil temperature ranges from 52 to 56 degrees F. The soil is usually moist but is dry in all parts between 4 and 12 inches for 50 to 60 consecutive days during the summer in most years.
The A horizon has chroma of 1 or 2. It is cobbly or gravelly silty clay loam with 25 to 35 percent coarse fragments.
The B horizon has hue of 7.5 or 10YR, value of 3 or 4 moist, 4 through 6 dry, and chroma of 2 through 4. Dry value of 6 and chroma of 4 occur below 20 inches. It is very gravelly, very cobbly, or extremely cobbly clay. It averages 40 to 50 percent clay, 15 to 40 percent gravel and 20 to 45 percent cobbles.
COMPETING SERIES: These are the Dixonville and Skookum series. Dixonville soils have less than 35 percent rock fragments in the particle-size control section and have bedrock at a depth of 20 to 40 inches. Skookum soils have montmorillonitic mineralogy and are 20 to 40 inches deep to bedrock.
GEOGRAPHIC SETTING. Marcola soils generally are on gently sloping fans at the mouths of steep canyons around the margins of valleys at elevations ranging from 400 to 1,200 feet. Slopes range from 2 to 7 percent. The soils formed in alluvium and colluvium weathered from mixed sedimentary and volcanic rock sources. The climate is subhumid with warm dry summers and cool moist winters. The mean annual precipitation is 40 to 60 inches. The mean January temperature is 38 degrees F., the mean July temperature is 67 degrees F., and the mean annual temperature is 50 to 54 degrees F. The frost-free season is 165 to 210 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Abiqua, Hazelair, McAlpin, Philomath, Waldo and the competing Dixonville soils. Abiqua, McAlpin, and Waldo soils are on adjacent flood plains. Hazelair and Philomath soils are on adjacent uplands. Abiqua, McAlpin, and Waldo soils do not have an argillic horizon, have less than 35 percent rock fragments, and are well, moderately well, and poorly drained respectively. Hazelair soils are 20 to 40 inches deep to a paralithic contact, and contain less than 35 percent rock fragments. Philomath soils are less than 20 inches deep to a paralithic contact.
DRAINAGE AND PERMEABILITY: Moderately well drained; medium runoff; slow permeability.
USE AND VEGETATION: These soils are used mainly for pasture, with some hay, grain, row crops, orchards, timber, and Christmas trees. Native vegetation is Douglas-fir, Oregon white oak, poison-oak, wild rose, forbs, grasses, and other shrubs.
DISTRIBUTION AND EXTENT: Margins of the Willamette Valley and possibly other interior valleys of western Oregon. The series is of limited extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Lane County Area, Oregon, 1981.