LOCATION SWIFTON MTEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive Typic Palecryalfs
TYPICAL PEDON: Swifton gravelly loam - forested (Colors are for dry soil unless otherwise noted.)
0i--0 to 1 inch; undecomposed needles and matted dark colored organic material.
E1--1 to 4 inches; light gray (10YR 7/2) gravelly sandy loam, grayish brown (10YR 5/2) moist; weak very thin platy structure; soft, very friable, nonsticky, nonplastic; many medium and fine roots; common fine and few medium tubular pores; 20 percent gravel; very strongly acid (pH 4.5); clear irregular boundary. (2 to 15 inches thick)
E2--4 to 16 inches; pale brown (10YR 6/3) gravelly loam, brown (10YR 4/3) moist; weak fine and very fine blocky structure; slightly hard, very friable, nonsticky, nonplastic; many medium and fine roots; few fine tubular pores; 20 percent gravel; very strongly acid (pH 4.5); clear smooth boundary. (O to 15 inches thick)
E3--16 to 23 inches; light gray (10YR 7/2), pale brown (10YR 6/3) crushed, gravelly loam, dark grayish brown (10YR 4/2) moist; weak medium and fine blocky structure; hard, friable, slightly sticky, slightly plastic; common fine and medium roots; few fine tubular pores; 20 percent gravel; very strongly acid (pH 4.5); clear smooth boundary. (5 to 10 inches thick)
E/B--23 to 38 inches; light gray (10YR 7/2) and grayish brown (10YR 5/2) gravelly sandy clay loam, dark grayish brown (10YR 4/2) and brown (10YR 4/3) moist; (about 40 percent of the mass is in a very fine mixed color pattern having skeletans of light gray clean silt and sand about 1 mm thick on outer walls of peds); moderate medium blocky structure; hard, friable, slightly sticky, slightly plastic; common fine and medium roots; common fine tubular pores; 25 percent gravel; strongly acid (pH 5.5); gradual smooth boundary. (5 to 20 inches thick)
B/E--38 to 53 inches; light gray (10YR 7/2) gravelly sandy clay loam, dark grayish brown (10YR 4/2) moist- the E horizon material dominates the color but there are common medium distinct mottles of yellowish brown (10YR 5/4) and skeletans of light gray clean silt and sand about 1 mm thick on outer walls of peds; moderate medium blocky structure; very hard, friable, moderately sticky, moderately plastic; few fine roots; few fine and large tubular pores; 30 percent gravel; moderately acid (pH 6.0); clear smooth boundary. (O to 15 inches thick)
Bt--53 to 73 inches; yellowish brown (10YR 5/4) sandy clay loam, dark grayish brown (10YR 4/2) moist; moderate medium and fine blocky structure; very hard, friable, moderately sticky, moderately plastic; few fine roots; few fine and large tubular pores; 40 percent coarse fragments; distinct clay film on coarse fragments, in pores, and along root channels; slightly alkaline (pH 7.5).
TYPE LOCATION: Glacier County, Montana; west side of State Highway No. 49, 1.5 miles north of East Glacier; 1,400 feet south and 1,600 feet west of NE corner of section 12, T.31N., R.13W.
RANGE IN CHARACTERISTICS: Coarse fragments in the upper 3 or 4 feet range from very few up to 35 percent, mostly pebble and cobble size but with some stones. A higher percentage of coarse material is common below 4 feet and in some pedons there is shale or sandstone bedrock below 5 feet. The mean annual soil temperature ranges from 44 to 46 degrees F. and average winter soil temperature ranges from 31 to 33 degrees F. under a heavy blanket of snow. There is a thin (l to 3 inches thick) Al horizon between the forest litter and the A2 horizon in some pedons. The A2 horizon may be uniformly light gray to depths 15 or 20 inches but more commonly has a subhorizon that is stronger in chroma and lower in value. This stronger chroma may continue into the B2t horizon but commonly grays out again above the B2t horizon. The B2t horizon occurs at depths ranging from 24 to 60 inches below the surface and has clay content ranging from 25 to 35 percent. It is usually 2 to 3 feet thick and grades into the C horizon material which is lighter in color and contains less clay.
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Swifton soils are on rolling, hllly, and steep glacial till deposits in and adjacent to the Rocky Mountains. The elevation ranges from 4,600 to 6,500 feet. The soils formed in loam and clay loam materials from argillite, quartzite, sandstone, and limestone rocks. Probable range in precipitation is 20 to 35 inches, with about half falling as snow. Mean annual air temperature ranges from 38 to 42 degrees F. and mean summer temperature from 46 to 50 degrees
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Loberg, Michelson, Mord and Nettleton series. Loberg, Mord and Nettleton soils have more than 35 percent clay in the B2t horizon. Michelson soils lack an AB horizon and have a Cca horizon.
DRAINAGE AND PERMEABILITY: Well-drained; moderately permeable.
USE AND VEGETATION: Many of the timbered areas have been logged. Forest grazing and watershed are the main uses with limited timber production. The main tree species are lodgepole pine, Douglas fir, and Englemann spruce. Subalpine fir, limber pine and aspen are also common.
DISTRIBUTION AND EXTENT: Swifton soils are moderately extensive, occurring along the eastern Rocky Mountain front in western Montana.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Glacier County (Blackfeet Reservation-Cut Bank Area), Montana, 1969.