LOCATION OLGA NDEstablished Series
TAXONOMIC CLASS: Fine, smectitic, frigid Alfic Vertic Argiudolls
TYPICAL PEDON: Olga silty clay loam - on a southeast-facing convex slope of 15 percent under mixed hardwoods and grass. (Colors are for dry soil unless otherwise stated. Where described, the soil was moist throughout)
Oi--1 to 0 inches; partly decomposed organic matter consisting of tree leaves, matted grass, and roots. (0 to 3 inches thick)
A--0 to 3 inches; very dark gray and gray (10YR 3/1 and 5/1) silty clay loam, black (10YR 2/1) moist; strong fine subangular blocky structure parting to moderate fine granular; very hard, friable, sticky and plastic; many roots; many fine pores; slightly acid; clear smooth boundary. (2 to 7 inches thick)
E--3 to 11 inches; gray (10YR 5/1) silty clay loam, very dark gray (10YR 3/1) moist, crushed; strong very fine subangular blocky structure; extremely hard, firm, sticky and plastic; many fine and common coarse roots; light gray (10YR 7/1) coatings on faces of peds; medium acid; diffuse wavy boundary. (4 to 11 inches thick)
Bt1--11 to 19 inches; light brownish gray and grayish brown (2.5Y 6/2 and 5/2) silty clay, dark grayish brown (2.5Y 4/2) moist, crushed; strong medium prismatic structure parting to strong coarse subangular blocky; extremely hard, very firm, sticky and plastic; common fine, medium and coarse roots; common fine and medium pores; very dark brown (10YR 2/2) moist coatings on vertical faces of peds; few small pebbles; medium acid; gradual smooth boundary.
Bt2--19 to 31 inches; light brownish gray (2.5Y 6/2) silty clay, dark grayish brown (2.5Y 4/2) moist; strong medium prismatic structure parting to strong coarse angular blocky; extremely hard, very firm, sticky and plastic; common medium and coarse roots; common medium pores; common thin clay films on faces of peds and pores; few pebbles; strongly acid; gradual smooth boundary.
Bt3--31 to 42 inches; grayish brown (2.5Y 5/2) silty clay, olive brown (2.5Y 4/4) moist; strong medium prismatic structure parting to strong medium and coarse angular blocky; extremely hard, very firm, sticky and plastic; few fine and coarse roots; common fine pores; common fine clay films on surfaces of peds and pores; strongly acid; gradual smooth boundary. (Combined Bt horizons 14 to 38 inches thick)
C--42 to 60 inches; light brownish gray (2.5Y 6/2) silty clay, dark grayish brown (2.5Y 4/2) moist; massive; extremely hard, very firm, sticky and plastic; few fine roots; few pebbles of shale fragments and granite; medium acid.
TYPE LOCATION: Pembina County, North Dakota; about 2 miles south and 1/2 mile west of Concrete; 2100 feet east and 160 feet north of the southwest corner, sec. 31, T. 161 N., R. 56 W.
RANGE IN CHARACTERISTICS: The solum contains 1 to 5 percent by volume of coarse fragments and a few large stones. The mollic epipedon ranges from 7 to 16 inches in thickness.
The A horizon has 10YR hue, value of 3 to 5 and 2 moist, and chroma of 1. It typically is clay loam or silty clay loam, but included is clay and silty clay. It ranges from neutral to medium acid.
The E horizon has 10YR or 2.5Y hue, value of 4 to 6 and 2 to 4 moist, and chroma of 1 or 2. It is clay loam, silt loam or silty clay loam. It has uncoated silt or sand grains on the faces of peds, which have value of 6 or 7. The E horizon ranges from slightly acid to strongly acid.
The Bt horizon has 2.5Y or 5Y hue, value of 5 or 6 and 3 to 5 moist, and chroma of 1 to 4. It is clay or silty clay averaging between 45 and 60 percent clay. It has moderate or strong grades of structure. The Bt horizon ranges from medium to very strongly acid.
The C horizon has hue of 2.5Y or 5Y, value of 5 to 7 and 4 to 6 moist, and chroma of 2 to 4. It is clay loam, silty clay or clay. It is very strongly acid to slightly acid. Some pedons have many shale fragments or shale bedrock within depths of 40 to 60 inches. Chroma of 1 is allowed in the C horizons of those pedons. A few pedons are neutral or slightly alkaline below depths of 40 inches.
COMPETING SERIES: This is the Rolette series in the same family. Rolette soils range from neutral to slightly alkaline in the Bt horizon. In addition, they do not have coarse fragments.
GEOGRAPHIC SETTING: Olga soils are on gently sloping to steep sides of valleys and have slope gradients of 3 to 35 percent. The soils formed in clayey colluvium from shale bedrock. The mean annual air temperature ranges from 37 to 39 F, and the mean annual precipitation from 15 to 20 inches. Most of the moisture falls in the spring and summer.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Rolette soils and the Barnes, Bottineau, Brantford, Buse, Kelvin, Rolla, Vang, Walsh and Waukon soils. Rolette and Rolla soils are on nearby glacial lake plains. Rolla soils do not have a mollic epipedon or coarse fragments, and are very fine. Barnes and Buse soils are on nearby till plains which were under grass. Both soils are fine-loamy. Bottineau, Kelvin and Waukon soils are on nearby glacial till plains. Bottineau and Waukon soils are fine-loamy. Kelvin and Waukon soils do not have a mollic epipedon. Brantford, Vang and Walsh soils are on nearby delta and outwash areas. Brantford and Vang soils are fine-loamy over sandy or sandy-skeletal. Walsh soils are fine-loamy.
DRAINAGE AND PERMEABILITY: Well drained. Runoff is medium to very high depending on slope. Permeability is slow.
USE AND VEGETATION: Used for pasture; some are cropped to small grain, hay, and pasture. Native vegetation is oak, birch, elm, aspen, sumac, buckbrush, poison-ivy, Canada wildrye, Virginia wildrye.
DISTRIBUTION AND EXTENT: Northeastern North Dakota along the western edge of glacial Lake Agassiz, along the plateau escarpment locally known as the Pembina Mountains. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: St. Paul, Minnesota
SERIES ESTABLISHED: Pembina County, North Dakota, 1972.
REMARKS: Diagnostic horizons and features recognized in this pedon are: mollic epipedon - the zone from the surface of the soil to a depth of 11 inches (A and E horizons); argillic horizon - the zone from 11 to 42 inches (Bt1, Bt2, and Bt3 horizons).