LOCATION DONNER UTEstablished Series
TAXONOMIC CLASS: Fine, smectitic, frigid Ultic Argixerolls
TYPICAL PEDON: Donner cobbly loam, rangeland. (Colors are for moist soils unless otherwise noted.)
A11--0 to 2 inches; very dark brown (10YR 2/2) cobbly loam, dark grayish brown (10YR 4/2) dry; weak medium platy structure that parts to weak medium granular; slightly hard, friable, slightly sticky and nonplastic; common fine and very fine, few medium roots; common fine and few medium pores; 10 percent gravel; and 15 percent cobbles; slightly acid (pH 6.2); abrupt smooth boundary. (2 to 10 inches thick)
A12--2 to 6 inches; very dark brown (10YR 2/2) loam, dark grayish brown (10YR 4/2) dry; weak medium subangular blocky structure that parts to weak medium granular; slightly hard, friable, slightly sticky and nonplastic; common fine and very fine, few medium roots; common fine pores; 1 percent gravel ; medium acid (pH 6.0); clear smooth boundary. (0 to 10 inches thick)
B21t--6 to 10 inches; very dark brown (10YR 2/2) clay loam, dark grayish brown (10YR 4/2) dry; weak medium subangular blocky structure that parts to moderate coarse granular; hard, firm, sticky and plastic; common fine, very fine, and few medium roots; common fine pores; 20 percent gravel; slightly acid (pH 6.2); abrupt wavy boundary. (2 to 16 inches thick)
B22t--10 to 15 inches; dark brown (10YR 3/3) heavy clay loam, brown (10YR 4/3) dry; weak coarse prismatic structure that parts to moderate coarse subangular blocky; extremely hard, very firm, sticky and plastic; few very fine, medium roots; few fine pores; common thin and few moderately thick clay films on faces of peds; 5 percent gravel; slightly acid (pH 6.2); clear wavy boundary. (4 to 22 inches thick)
B23t--15 to 34 inches; dark brown (7.5YR 4/3) silty clay, brown (10YR 5/3) dry; weak coarse prismatic structure that parts to moderate coarse subangular blocky; extremely hard, extremely firm, sticky and plastic; few very fine and medium roots; few fine pores; continuous thin and common moderately thick clay films on faces of peds; 5 percent gravel; medium acid (pH 6.0); abrupt wavy boundary. (0 to 22 inches thick)
C1r--34 to 44 inches; soft, weathered andesite that has the following characteristics when crushed; dark grayish brown (10YR 4/2) clay loam, yellowish brown (10YR 5/4) dry; rock structure; hard, firm, sticky and plastic; few very fine and medium roots concentrated in crevices; slightly acid (pH 6.4); gradual wavy boundary.
C2r--44 to 60 inches; soft, weathered andesite that has the following characteristics when crushed; yellowish brown (10YR 5/4) loam, very pale brown (10YR 7/4) dry; rock structure; hard, firm, slightly sticky and nonplastic; few very fine and medium roots concentrated in crevices; moderately alkaline (pH 8.30.
TYPE LOCATION: Morgan County, Utah; about 5 1/4 miles south and 1/4 mile east of East Canyon Dam; 1,600 feet west and 2,300 feet north of the SE corner of section 3, T.1N., R.3E.
RANGE IN CHARACTERISTICS: The mollic epipedon is 10 to 19 inches thick. Base saturation is less than 75 percent in part or all of the upper 30 inches. The combined thickness of the A1 and B2t horizons is 23 to 40 inches. The mean annual soil temperature at depth of 20 inches ranges from 39 to 45 degrees F. The mean annual summer temperature ranges from 60 to 66 degrees F. The soils are usually moist but are dry for 50 to 85 consecutive days during the later part of the summer. Rock fragments consist of pebbles and cobbles and range from 10 to 40 percent in the A1 horizon and from 0 to 20 percent in the B2t horizon.
The A1 horizon has value of 3 or 4 dry, 2 or 3 moist, and chroma of 2 or 3 moist. It ranges from loam to gravelly or cobbly loam. This horizon is medium or slightly acid and ranges from 6 to 15 inches thick.
The B2t horizon has hue of 10YR or 7.5YR, value of 4 through 6dry, 2 through 4 moist, and chroma of 2 through 4 dry and moist. It ranges from heavy clay loam to clay or silty clay and has 35 to 45 percent clay. This horizon has weak or moderate , medium or coarse prismatic to weak through strong, fine through coarse subangular blocky structure that parts to moderate coarse granular in some subhorizons. The B2t horizon has few to continuous, thin or moderately thick clay films. It is medium acid to slightly acid and ranges from 10 to 25 inches thick.
Soft weathered tuffaceous sandstone or andesite occurs at depths of 20 to 40 inches.
COMPETING SERIES: These are the Bertag, Booth, Dumecq, Lamonex, Manila, Marsden, Ostler, Rands and Rob Roy series. All of these soils except Bertag and Lamonex have more than 75 percent base saturation throughout the upper 30 inches. Bertag soils have mollic epipedons 20 to 38 inches thick. Dumecq soils have chroma of 1.5 or less in the A1 horizon. Lamonex soils have a lithic contact at depths of 20 to 40 inches. Manila, Marssden, Ostler and Rande soils are more than 40 inches deep to bedrock. Rob Roy soils are mildly or moderately alkaline and have a lithic contact at depths of 20 to 40 inches.
GEOGRAPHIC SETTING: Donner soils are at elevations of 5,660 to 7,200 feet. They occur on mountain slopes and on foot slopes.Slopes range from 10 to 50 percent. These soils formed in residuum and local alluvium form tuffaceous sandstone and andesite. The climate is moist subhumid and the average annual precipitation ranges from 18 to 25 inches. The mean annual temperature is 41 to 43 degrees F. The mean summer temperature is 59 to 63 degrees F. The frost free season ranges from 70 to 90 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Bertag soils and the Croydon, Hawkins, Henefer, Manila, Richville, Yeates Hollow soils. Croydon soils have summer soil temperature of less than 59 degrees F. Hawkins soils lack argillic horizons, crack to the surface in late summer and are more than 60 inches to soft rock. Henefer soils have mollic epipedons more than 20 inches thick. Manila soils are more than 50 inches to soft rock. Richville soils lack mollic epipedons and argillic horizons and have less than 35 percent clay in the control section. Yeates Hollow soils have more than 35 percent rock fragments and are 40 to more than 60 inches to bedrock.
DRAINAGE AND PERMEABILITY: Well drained; medium runoff; slow permeability.
USE AND VEGETATION: These soils are used for range, wildlife habitat and watershed. The present native vegetation is big sagebrush, bluebunch wheatgrass, oak, serviceberry, cheat grass, balsamroot, basin wildrye, bitterbrush and snowberry.
DISTRIBUTION AND EXTENT: Northern Utah. The series is inextensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Morgan Area, Morgan County, Utah, 1974.