LOCATION MEDCO OREstablished Series
TAXONOMIC CLASS: Fine, smectitic, mesic Ultic Haploxerolls
TYPICAL PEDON: Medco cobbly clay loam, on an east facing concave slope of 15 percent under conifers, hardwoods, and shrubs at
2,040 feet elevation. (Colors are for moist soil unless
otherwise noted.)
A1--0 to 2 inches; very dark brown (10YR 2/2) cobbly clay
loam, dark gray (10YR 4/1) dry; weak fine and medium granular structure; slightly hard, very friable, slightly sticky and
slightly plastic; common fine and medium roots; many very fine irregular pores; 5 percent gravel and 10 percent cobbles;
neutral; abrupt smooth boundary. (2 to 5 inches thick)
A2--2 to 7 inches; very dark grayish brown (10YR 3/2) cobbly
clay loam, gray (10YR 5/1) dry; moderate fine and medium
subangular blocky structure; slightly hard, friable, sticky and plastic; common fine and medium and few coarse roots; common very fine irregular and few very fine tubular pores; 5 percent gravel
and 10 percent cobbles; neutral; clear wavy boundary. (4 to 7
inches thick)
A3--7 to 12 inches; very dark grayish brown and dark brown
(10YR 3/2, 3/3) cobbly clay loam, gray and grayish brown (10YR
5/1, 5/2) dry; few fine faint dark reddish brown (5YR 3/3)
mottles; strong fine and medium subangular blocky structure;
hard, firm, sticky and plastic; common medium, and few fine and coarse roots; common very fine irregular and tubular pores; 10 percent gravel and 10 percent cobbles; slightly acid; abrupt
smooth boundary. (4 to 7 inches thick)
2Bw1--12 to 22 inches; brown (10YR 5/3, 7.5YR 4/2) clay, pale
brown and light brownish gray (10YR 6/3, 6/2) dry; strong fine
and medium angular blocky structure; extremely hard, very firm,
very sticky and very plastic; few medium and coarse roots; few
very fine irregular pores; many prominent stress cutans; 5
percent gravel; moderately acid; gradual smooth boundary. (5 to
12 inches thick)
2Bw2--22 to 30 inches; brown (10YR 5/3) clay, very pale brown
(10YR 7/3) dry; strong medium angular blocky structure; extremely hard, very firm, very sticky and very plastic; few medium and
coarse roots; few very fine tubular pores; many prominent stress cutans; 5 percent gravel; strongly acid; abrupt irregular
boundary. (5 to 12 inches thick)
3Cr--30 inches; soft tuffaceous bedrock.
TYPE LOCATION: Jackson County, Oregon; about 2 1/2 miles east of Brownsboro; 2,255 feet east and 2,495 feet north of the southwest corner of sec. 35, T. 35 S., R. 1 E.
RANGE IN CHARACTERISTICS: The soils are usually moist but are
dry between depths of 4 and 12 inches for 80 to 110 consecutive
days in the four months that follow the summer solstice. The
mean annual soil temperature is 47 to 54 degrees F. Depth to a paralithic contact is 20 to 40 inches. Few faint mottles are in
the solum, in some pedons, above the 2B horizon. The
particle-size control section averages 50 to 60 percent clay.
The A horizon has hue of 10YR and 7.5YR, value of 2 or 3 moist
and 4 or 5 dry. Typically it is 10 to 15 inches thick. It is
clay loam, or stony or cobbly clay loam with 0 to 15 percent
gravel; 0 to 20 percent cobbles and 0 to 15 percent stones.
Commonly there is a stone line at the lower boundary of this
horizon.
The 2B horizon has hue of 7.5YR, 10YR or 2.5Y, value of 4 or 5
moist and 4 to 7 dry, and chroma of 2 to 4 moist and 2 or 3 dry.
It is clay or cobbly clay and averages 5 to 30 percent rock
fragments of which 5 to 15 percent are gravel and 0 to 15 percent
are cobbles. It is moderately or strongly acid but may range to slightly acid.
COMPETING SERIES: There are no other series in this family.
GEOGRAPHIC SETTING: The Medco series consists of moderately
deep, moderately well drained soils on hillslopes. These soils formed in colluvium and alluvium derived dominantly from tuffs, breccias, and andesite. Slopes range from 1 to 50 percent. Elevation is 1,500 to 4,000 feet. The mean annual precipitation
is 20 to 40 inches and the mean annual air temperature is 45 to
52 degrees F. The frost-free period is 100 to 160 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Carney,
McMullin,
and
McNull soils. Carney soils are clay throughout and crack to
the surface from a depth of a least 20 inches. McMullin soils
are shallow, well drained, and have loamy textures. McNull soils
are well drained, have less than 50 percent clay in the control section, and have a hue of 5YR.
DRAINAGE AND PERMEABILITY: Moderately well drained; medium to
rapid runoff; very slow permeability. A water table is present
at 0.5 to 1.5 feet from December to March.
USE AND VEGETATION: These soils are used for grazing, irrigated pasture, timber production, and wildlife habitat. Native
vegetation is Oregon white oak, ponderosa pine, shrubs, and
grasses in dry areas; and Douglas fir, ponderosa pine, shrubs,
and grasses in moist areas.
DISTRIBUTION AND EXTENT: Southwestern Oregon. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Jackson County Area, Oregon, 1988.
ADDITIONAL DATA: OSU Soil Characterization Data on 2 pedons:
(S79 Oreg. 029-4-1 thru 5) and (S73 Oreg. 15-4-1 thru 5).