LOCATION BLACKSPOT IDEstablished Series
The Blackspot series consists of shallow, well drained soils that
formed in mixed colluvium over calcareous quartzite residuum.
Blackspot soils are on mountainsides and have slopes of 30 to 60
percent. Permeability is moderately. The average annual precipitation
is about 14 inches, and the average annual air temperature is about 41
degrees F.
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, frigid, shallow Haplic Durixerolls
Durixerolls.
TYPICAL PEDON: Blackspot very gravelly loam on a 45 percent slope at
an elevation of 5,500 feet in rangeland. When described on July 16,
1983, the soil was dry throughout. (Colors are for dry soil unless
otherwise noted.)
A1--0 to 1 inches; grayish brown (10YR 5/2) very gravelly loam,
very dark grayish brown (10YR 3/2) moist; weak fine granular structure;
soft, very friable, slightly sticky and slightly plastic; many very
fine, fine, and medium roots; many very fine and fine tubular pores;
about 35 percent pebbles; slight effervescence (10 percent calcium
carbonate); mildly alkaline (pH 7.8); clear wavy boundary (0 to 3
inches thick)
A2--1 to 7 inches; brown (10YR 5/3) very gravelly loam, dark brown
(10YR 3/3) moist; moderate fine granular structure; soft, friable,
slightly sticky and slightly plastic; common very fine and fine roots;
common very fine and fine tubular pores; about 5 percent cobbles and 40
percent pebbles; strong effervescence (15 percent calcium carbonate);
moderately alkaline (pH 8.0); gradual wavy boundary. (4 to 9 inches
thick)
Bk--7 to 11 inches; pale brown (10YR 6/3) very gravelly loam, brown
(10YR 4/3) moist; weak fine and medium subangular blocky structure;
slightly hard, friable, slightly sticky and slightly plastic; common
very fine and fine roots; common very fine and fine tubular pores;
about 5 percent cobbles and 45 percent pebbles; violent effervescence
(30 percent calcium carbonate); moderately alkaline (pH 8.2); clear
wavy boundary. (3 to 8 inches thick)
Bqk--11 to 14 inches; pale brown (10YR 6/3) very gravelly loam,
brown (10YR 4/3) moist; moderate fine and medium subangular blocky
structure; slightly hard, friable, slightly sticky and slightly
plastic; few very fine and fine roots; few fine tubular pores; about 5
percent cobbles and 50 percent pebbles, including 10 percent duripan
fragments; violent effervescence (35 percent calcium carbonate);
strongly alkaline (pH 8.6); abrupt wavy boundary. (0 to 4 inches
thick)
2Bqkm--14 to 19 inches; white indurated duripan, very pale brown
(10YR 7/3) moist; massive; few fine roots matted on top of duripan;
about 10 percent cobbles and 60 percent pebbles cemented in place;
violent effervescence (25 to 40 percent calcium carbonate); strongly
alkaline (pH 8.8); abrupt broken boundary. (3 to 10 inches thick)
2R--19 inches; fractured calcareous quartzite bedrock with 2Bqkm
material in fractures.
TYPE LOCATION: Blaine County, Idaho about 8 miles south and 3 miles
east of Gannett; 400 feet west and 1200 feet south of the northeast
corner of section 18, T. 2 S., R. 18 E.
RANGE IN CHARACTERISTICS:
Average annual soil temperature - 42 to 45 degrees F.
Thickness of mollic epipedon - 7 to 10 inches
Depth to indurated duripan - 13 to 17 inches
Depth to bedrock - 19 to 22 inches
A horizon
Hue- 10YR or 2.5Y
Value- 4 or 5 dry, 2 or 3 moist
Chroma- 2 or 3, dry or moist
Reaction - mildly to moderately alkaline
Bk horizon
Hue- 10YR or 2.5Y
Value- 6 or 7 dry, 4 or 5 moist
Chroma- 2 or 3 dry or moist
Rock fragments - 5 to 15 percent cobbles, 40 to 50 percent pebbles
Clay content - 10 to 18 percent
Texture - GRV-L, GRX-L, GRX-SL
Reaction - moderately alkaline to strongly alkaline
Effervescence - strong to violent
2Bqkm horizon
Value- 7 or 8 dry, 6 or 7 moist
Chroma- 2 or 3 dry or moist
Rock fragments - 5 to 10 percent cobbles, 50 to 60 percent pebbles
Laminar capping - continuous; 1 to 3 mm thick
Duripan - indurated
COMPETING SERIES: There are no other series recognized in the same
family. The Loza soils lack bedrock below the duripan.
GEOGRAPHIC SETTING: Blackspot soils are on mountainsides. Slopes
range from 30 to 60 percent. Elevation ranges from 4,700 to 6,000
feet. The soils formed from colluvium over calcareous quartzite
residuum. The average annual precipitation is 12 to 16 inches, most of
which falls as snow and early spring rain. The average annual air
temperature is 40 to 44 degrees F. The frost-free season is 60 to 90
days.
GEOGRAPHICALLY ASSOCIATED SOILS: The are the Elksel, Friedman,
Furshur, Peeveywell, Prudy, and Winridge soils. Elksel soils are
clayey-skeletal in the control section. Furshur soils have more than
35 percent clay in the control section and are 10 to 20 deep to a
duripan. Friedman have Pachic epipedons. Peevywell soils are
moderately deep to a duripan and have more than 35 percent clay in the
control section. Prudy soils are deep to a duripan. Winridge soils
are moderately deep and have more than 35 percent clay in the control
section. Povey soils occur on the same landscape. Elksel, Furshur,
Peevywell, and Winridge soils occur on mountain sides formed from
tertiary volcanics. Prudy soils occur on similiar landscapes on north
and east-facing slopes.
DRAINAGE AND PERMEABILITY: Well drained; rapid to very rapid runoff;
and moderately rapid permeability.
USE AND VEGETATION: Mainly used for rangeland. Vegetation is Black
sagebrush and Bluebunch wheatgrass.
DISTRIBUTION AND EXTENT: Blackspot soils are inextensive in south
central Idaho.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Blaine County, Idaho, 1985.
REMARKS: Mollic epipedon occurs from the soil surface to approximately
7 inches (A1 and A2 horizons)
Duripan occurs in the zone from 14 to 19 inches (Bqkm horizon)
National Cooperative Soil Survey