LOCATION PRAG OREstablished Series
TAXONOMIC CLASS: Fine, smectitic, frigid Pachic Palexerolls
TYPICAL PEDON: Prag cobbly loam, range. (Colors are for moist soil unless otherwise noted.)
A1--0 to 3 inches; black (10YR 2/1) cobbly loam, dark gray (10YR 4/1) dry; weak thin platy structure; slightly hard, friable, slightly sticky and slightly plastic; many very fine roots; many very fine irregular pores; 10 percent gravel and 15 percent cobbles; neutral (pH 6.6); clear smooth boundary. (3 to 6 inches thick)
A2--3 to 9 inches; black (10YR 2/1) cobbly loam, dark gray (10YR 4/1) dry; weak to moderate fine subangular blocky structure; hard, friable, slightly sticky and slightly plastic; many very fine roots; many very fine tubular pores; 10 percent gravel and 15 percent cobbles; neutral (pH 6.8); abrupt smooth boundary. (3 to 6 inches thick)
2Bt1--9 to 14 inches; very dark grayish brown (10YR 3/2) very cobbly clay, dark grayish brown (10YR 4/2) dry; moderate coarse prismatic structure parting to strong medium subangular blocky; very hard, very firm, very sticky and very plastic; few very fine roots; common very fine tubular pores; prominent discontinuous very dark brown (10YR 2/2) clay films on ped faces; 10 percent gravel, 20 percent cobbles and 10 percent stones; neutral (pH 7.2); clear smooth boundary. (5 to 8 inches thick)
2Bt2--14 to 22 inches; dark brown (10YR 3/3) cobbly clay, brown (10YR 5/3) dry; moderate coarse prismatic structure parting to strong medium subangular blocky; very hard, very firm, very sticky and very plastic; few very fine roots; few very fine tubular pores; prominent discontinuous very dark brown (10YR 2/2) clay films on faces of peds; 5 percent gravel, 20 percent cobbles and 5 percent stones; slightly alkaline (pH 7.4); clear smooth boundary. (6 to 10 inches thick)
2Btk--22 to 35 inches; brown (10YR 4/3) cobbly clay, brown (10YR 5/3) dry; weak medium subangular blocky structure; very hard, firm, very sticky and very plastic; few very fine roots; few very fine tubular pores; faint discontinuous clay films on ped faces; 15 percent cobbles, 10 percent gravel and 5 percent stones with coatings of lime; common light gray calcium carbonate segregations; moderately alkaline (pH 8.0); abrupt wavy boundary. (3 to 15 inches thick)
2Bk--35 to 40 inches; brown (10YR 4/3) very cobbly loam, brown (10YR 5/3) dry; massive; very hard, firm, very sticky and very plastic; 50 percent cobbles; common light gray calcium carbonate segregations; moderately alkaline (pH 8.0); abrupt wavy boundary. (0 to 8 inches thick)
3Cr--40 to 50 inches; moderately cemented sediments.
TYPE LOCATION: Jefferson County, Oregon; 50 feet east of dirt road in the SE1/4 SE1/4 NW1/4 section 3, T. 11 S., R. 16 E.
RANGE IN CHARACTERISTICS: The mean annual soil temperature is 43 to 47 degrees F. The soils are usually moist but are dry for 70 to 90 consecutive days between depths of 4 and 12 inches within the 3-month period following the summer solstice. Depth to moderately cemented sediments is 20 to 40 inches. The content of angular rock fragments is 10 to 35 percent. It is neutral to moderately alkaline. The mollic epipedon is 20 to 30 inches thick. Depth to secondary carbonates is 20 to 30 inches.
The A horizon has value of 2 or 3 moist, 4 or 5 dry, chroma of 1 or 2 dry and moist. It is silt loam or loam with 10 to 15 percent cobbles, 5 to 10 percent gravel and 18 to 27 percent clay. It has weak to moderate platy, granular or subangular blocky structure.
The 2Bt horizon has value of 4 or 5 dry and 3 or 4 moist, and chroma of 2 or 3 dry and moist. It is clay with 40 to 60 percent clay with an increase in clay content of 15 percent or more (absolute) within a vertical distance of 1 inch at the upper boundary. It has 0 to 10 percent stones, 15 to 20 percent cobbles and 5 to 10 percent gravel. It has moderate coarse or medium prismatic and strong medium or fine subangular or angular blocky structure.
COMPETING SERIES: These are the Goring, Greentimber, Letavaria, Maughen and Skullgulch series. All of the series are very deep.
GEOGRAPHIC SETTING: Prag soils are on hills and mountains at elevations of 3,500 to 4,500 feet. Slopes are 2 to 70 percent. These soils formed in colluvium and residuum from sediments, tuffs, rhyolites and basalts. The upper part has some influence of ash. The mean winter temperature is 28 to 32 degrees F., mean summer temperature is 58 to 62 degrees F., and mean annual temperature is 42 to 45 degrees F. The mean annual precipitation is 13 to 16 inches. The frost-free period is 30 to 100 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Boardtree, Ginser, Hankins, Tub and Yawkey soils. Boardtree, Hankins, and Yawkey soils are in an association at the higher elevations mostly on north slopes. Boardtree soils are ashy in the upper part of the profile. Hankins soils lack an abrupt textural change. Yawkey soils have more than 35 percent coarse fragments in the control section. Ginser soils lack argillic horizons and have more than 35 percent coarse fragments as a weighted average in the control section. Tub soils have a mean annual soil temperature of greater than 47 degrees F., and occur at slightly lower elevations or on south-facing slopes.
DRAINAGE AND PERMEABILITY: Well-drained; medium to rapid runoff; slow permeability.
USE AND VEGETATION: The soils are used for range, wildlife and water supply purpose. Native plants are bunchgrasses, brush and juniper. Ecological sites include JD Clayey South 12-16 inch PZ (R010XB045OR) and JD North 12-16 inch PZ (R010XB070OR).
DISTRIBUTION AND EXTENT: East-central Oregon; MLRA 10. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Jefferson County (Trout Creek-Shaniko Area), Oregon, 1970.
REMARKS: Diagnostic horizons and other features:
Mollic epipedon (pachic) - 0 to 22 inches
Argillic horizon - 9 to 35 inches
Paralithic contact - 40 inches
PSCS 9 to 29 inches
Xeric moisture regime