LOCATION SISTERS OR

Established Series
Rev. WMF/TDT
06/2011

SISTERS SERIES

The Sisters series consists of deep and very deep, well drained soils on volcanic uplands. They formed in ash over colluvium or residuum. Slopes are 0 to 50 percent. The mean annual precipitation is about 25 inches and the mean annual temperature is about 44 degrees F.

TAXONOMIC CLASS: Ashy over loamy, glassy over mixed, superactive, frigid Humic Vitrixerands

TYPICAL PEDON: Sisters ashy loamy sand - woodland, on a 1 percent slopes at 4500 feet elevation. (When described (11/5/87), the soil was dry to 35 inches. Colors are for moist soil unless otherwise noted)

Oi--0 to 2 inches; slightly decomposed litter of ponderosa pine needles.

A1--2 to 4 inches; very dark brown (10YR 2/2) ashy loamy sand, dark yellowish brown (10YR 4/4) dry; weak fine granular structure; loose, nonsticky and nonplastic; common very fine and fine roots; many very fine interstitial pores; 5 percent gravel; 20 percent sand-size pumiceous ash (0.5 - 2.0 millimeters); neutral (pH 7.0); clear wavy boundary.

A2--4 to 13 inches; dark brown (10YR 3/3) ashy loamy sand, yellowish brown (10YR 5/4) dry; weak fine granular structure; loose, nonsticky and nonplastic; common fine and coarse and many medium roots; many very fine interstitial pores; 10 percent gravel; 40 percent sand-size pumiceous ash (0.5 - 2.0 millimeters); neutral (pH 7.0); gradual wavy boundary. (Combined thickness of the A horizon is 10 to 15 inches)

Bw--13 to 25 inches; dark yellowish brown (10YR 3/4) ashy loamy sand, yellowish brown (10YR 5/4) dry; single grain; loose, nonsticky and nonplastic; common fine, medium, and coarse roots; many very fine interstitial pores; 5 percent gravel; 40 percent sand-size pumiceous ash (0.5 - 2.0 millimeters); neutral (pH 7.0); gradual wavy boundary. (10 to 20 inches thick)

2Ab--25 to 37 inches; dark brown (7.5YR 3/4) sandy loam, brown (7.5YR 5/4) dry; weak fine subangular blocky structure; slightly hard, very friable, nonsticky and nonplastic; common fine and medium roots; many very fine interstitial pores; 10 percent gravel; 10 percent sand-size pumiceous ash (0.5 - 2.0 millimeters); neutral (pH 7.0); clear wavy boundary. (7 to 15 inches thick)

2Bwb1--37 to 49 inches; dark reddish brown (5YR 3/3) clay loam, brown (7.5YR 5/4) dry; weak coarse subangular blocky structure parting to weak fine platy; hard, firm, slightly sticky and slightly plastic; few fine roots; many fine and medium vesicular and tubular pores; 10 percent gravel; 10 percent sand-size pumiceous ash (0.5 - 2.0 millimeters); neutral (pH 7.2); gradual wavy boundary.

2Bwb2--49 to 62 inches; dark brown (7.5YR 3/4) loam, brown (7.5YR 5/4) dry; weak coarse subangular blocky structure; slightly hard, friable, nonsticky and nonplastic; few fine roots; many fine, medium, and coarse vesicular and tubular pores; 10 percent gravel; 10 percent sand-size pumiceous ash (0.5 - 2.0 millimeters); neutral (pH 7.2).

TYPE LOCATION: Deschutes County, Oregon; 2000 feet south and 300 feet east of the northwest corner of section 14, T.17 S, R. 10 E (Latitude 44 degrees, 6 minutes, 14 seconds N, Longitude 121 degrees, 29 minutes, 58 seconds W)

RANGE IN CHARACTERISTICS: These soils are usually moist they are dry in all parts of the soil moisture control section for 60 to 90 consecutive days after the summer solstice. The mean annual soil temperature is 42 to 47 degrees F. The mollic epipedon is 10 to 17 inches thick. Depth to the buried loamy material is 20 to 35 inches. Depth to bedrock is 40 to more than 60 inches. Reaction is neutral to slightly alkaline. The ash mantle (A and Bw horizons) contains 60 to 80 percent glass and glass-coated aggregate, phosphate retention is 40 to 70 percent, acid oxalate extractable aluminum plus one-half the acid oxalate extractable iron is 0.40 to 1.0 percent, and the 15-bar water content on dried and undried samples is 2 to 10 percent.

The A horizon has value of 2 or 3 moist and 4 or 5 dry and chroma of 2 or 3 moist and 3 or 4 dry. It contains 0 to 25 percent gravel and 20 to 50 percent sand-size pumiceous ash (0.5 - 2.0 millimeters). Field estimated clay content is 2 to 10 percent.

The Bw or AC horizon has hue of 7.5YR and 10YR, value of 2 through 7 moist and 2 through 8 dry and chroma of 2 through 6 moist and dry. The fine-earth texture is ashy loamy sand or ashy sand with 0 to 30 percent gravel, 0 to 25 percent paragravel and 20 to 50 percent sand-size pumiceous ash (0.5 - 2.0 millimeters). Field estimated clay content is 2 to 10 percent.

The 2Ab and 2Bwb horizon has a hue of 5YR, 7.5YR, or 10YR. value is 3 or 4 moist, 5 or 6 dry and chroma of 3 or 4 moist and dry. It is sandy loam, loam, clay loam or gravelly clay loam. It contains 0 to 25 percent gravel, 10 to 30 percent clay, and 5 to 20 percent sand-size pumiceous ash (0.5 - 2.0 millimeters).

COMPETING SERIES: These are the Barnellcreek, and Molson series. Barnellcreek soils have densic contacts of dense till at depths of 40 to 60 inches. Molson soils are not influenced by coarse and very coarse sand-size pumiceous ash and do not have ashy and sandy textures in the particle-size control section.

GEOGRAPHIC SETTING: The Sisters soils are on volcanic uplands at elevations of 3,200 to 5,000 feet. Slopes are 0 to 50 percent. These soils formed in ash over colluvium or residuum from volcanic rocks. The climate is characterized by cold, wet winters and hot, dry summers. The mean annual precipitation is typically 16 to 30 inches but can range to 14 inches. The mean annual temperature is 40 to 47 degrees F. The frost-free period is 30 to 90 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Fremkle, Fryrear, Henkle, Shroyton, Wanoga, and Yapoah soils. The Fremkle, Fryrear, Henkle, and Wanoga soils are on volcanic uplands and are less than 40 inches to bedrock. Shroyton soils are on volcanic uplands and have a cryic temperature regime. Yapoah soils are on volcanic uplands and are ashy-skeletal.

DRAINAGE AND PERMEABILITY: Well drained; rapid over moderately slow permeability.

USE AND VEGETATION: These soils are used for timber production, wildlife habitat, watershed, and recreation. Potential native vegetation is ponderosa pine, antelope bitterbrush, greenleaf manzanita, and Idaho fescue.

DISTRIBUTION AND EXTENT: Foot slopes and plateaus of the eastern slopes of the Cascade Mountains of central Oregon; MLRA 6. The series is not extensive.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon

SERIES ESTABLISHED: Deschutes County (Upper Deschutes River Area), Oregon, 1992.

REMARKS: Diagnostic horizons and features in this pedon are:

mollic epipedon - 2 to 13 inches (A1 and A2 horizon)

buried cambic horizon - the zone from 37 inches to more than 62 inches (2Bwb1, 2Bwb2 horizons)

andic soil properties - Based on laboratory data form the associated Wanoga Series. Ash mantle is from Mt. Mazama.

National Cooperative Soil Survey
U.S.A.