LOCATION ROCKBOTTOM MIEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, frigid Oxyaquic Hapludalfs
TYPICAL PEDON: Rockbottom stony silt loam - on a 3 percent slope in a forested area. (Colors are for moist soil unless otherwise stated.)
A--0 to 6 inches; very dark grayish brown (10YR 3/2) stony silt loam, light brownish gray (10YR 6/2) dry; moderate medium subangular blocky structure; friable; many fine to coarse roots; about 30 percent stones; medium acid; gradual wavy boundary. (4 to 7 inches thick)
A/B--6 to 10 inches; very dark gray (10YR 3/1), light brownish gray (10YR 6/2) dry (A) and dark grayish brown (10YR 4/2) (B) stony silt loam; A part is 75 percent of horizon; moderate medium subangular blocky structure; friable; many fine and medium roots; about 30 percent stones; medium acid; clear wavy boundary. (2 to 5 inches thick)
Bt--10 to 17 inches; brown (10YR 4/3) silty clay loam; medium fine subangular blocky structure; firm; common fine and medium roots; common distinct dark yellowish brown (10YR 4/4) clay films on faces of peds; about 5 percent cobbles; medium acid; gradual wavy boundary. (4 to 10 inches thick)
2Bt--17 to 29 inches; brown (10YR 4/3) extremely cobbly sandy clay loam; few fine prominent reddish brown (5YR 4/4) mottles in the lower part; weak coarse granular structure; friable; few fine and medium roots; few fine distinct dark yellowish brown (10YR 4/4) clay films on faces of peds; about 30 percent gravel and 50 percent cobbles; medium acid; clear smooth boundary. (5 to 15 inches thick)
3C1--29 to 38 inches; pale brown (10YR 6/3) very cobbly fine sandy loam; massive; friable; about 20 percent gravel and 15 percent cobbles; neutral; clear smooth boundary.
3C2--38 to 60 inches; pale brown (10YR 6/3) very gravelly fine sandy loam; massive; friable; about 35 percent gravel and 15 percent cobbles; neutral.
TYPE LOCATION: Chippewa County, Michigan on Sugar Island, 1255 feet east and 2760 feet south of the northwest corner of sec. 12, T. 47 N., R. 1 E.
RANGE IN CHARACTERISTICS: Solum thickness ranges from 20 to 40 inches. Volume of stones ranges from 15 to 35 percent in the A horizon and from 0 to 5 percent throughout the rest of the soil. Gravel content ranges from 0 to 5 percent in the A, A/B and Bt horizons and from 20 to 40 percent in the 2Bt and 3C horizons. Cobble content ranges from 0 to 10 percent in the upper finer textured layers and from 15 to 50 percent in the lower coarser-textured materials. Stony and very stony surface phases are recognized. Reaction ranges from strongly acid to neutral in the upper finer textured materials and from slightly acid to mildly alkaline in the coarser textured lower materials.
The A horizon has hue of 7.5YR or 10YR, value of 2 or 3, and chroma of 1 or 2. It is stony silt loam,stony loam or stony fine sandy loam. The A part of the A/B horizon has colors and textures similar to the A horizon. The B part of the A/B has hue of 5YR to 10YR, value of 4 or 5, and chroma of 2 to 4. It is silt loam or loam.
The Bt horizon has hue of 5YR to 10YR, value of 4 or 5, and chroma of 3 or 4. It is silty clay loam or clay loam. The 2Bt has colors similar to the Bt horizon. It is the very gravelly, extremely gravelly, very cobbly, or extremely cobbly analogues of sandy clay loam.
The C horizons have hue of 2.5YR to 10YR, value of 4 to 6, and chroma of 3 or 4. They are very gravelly, extremely gravelly, very cobbly, or extremely cobbly analogues of fine sandy loam or sandy loam.
COMPETING SERIES: These are the Abreu, Grizzly, Krakow (T), Macmeal, Mocmont, Pactola, Rockoa, Rumblecreek, Tecolote, Trapps, Vanocker, Wahatoya, and Yourame series in the same family and the similar Posen soils. The Abreu, Grizzly, Macmeal, Mocmont, Pactola, Rockoa, Rumblecreek, Tecolote, Trapps, Vanocker, Wahatoya and Yourame series are substantially drier in the soil moisture control section for the 120 days following the summer solstice. The Krakow soils have thinner and less acid sola and have rock fragments dominated by flagstones and channers. Posen soils do not have an argillic horizon.
GEOGRAPHIC SETTING: Rockbottom soils are on lake plains and the margins of lake plains and moraines. They formed in lacustrine deposits underlain by loamy-skeletal glacial till. Slopes range from 0 to 35 percent. The mean annual precipitation ranges from 28 to 35 inches, and the mean annual temperature ranges from 41 to 45 degrees F.
DRAINAGE AND PERMEABILITY: Moderately well drained and well drained. Surface runoff is slow or medium depending on slope. Permeability is moderately slow in the solum and moderate in the substratum.
USE AND VEGETATION: Most areas are wooded with quaking aspen, red maple, balsam fir, paper birch, sugar maple, white spruce and yellow birch being the primary species.
DISTRIBUTION AND EXTENT: Eastern Upper Peninsula of Michigan. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: St. Paul, Minnesota
SERIES PROPOSED: Chippewa County, Michigan, 1988. The source of the name is a creek on Sugar Island.
REMARKS: Classification changed to agree with ST Issue #17 on 2Sept 94 by CLG. Diagnostic horizons and features recognized in this pedon are: ochric epipedon - the zone from the surface to 10 inches (A and A/B horizons); argillic horizon - the zone from 10 to 29 inches (Bt and 2Bt horizons).