LOCATION GEORGOTTE ORTentative Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, mesic Xeric Haplohumults
TYPICAL PEDON: Georgotte silt loam, on a south-facing, convex, 35 percent slopes at an elevation of 1230 feet. (Colors are for moist soil unless otherwise noted)
A--0 to 9 inches; dark brown (7.5YR 3/2) broken face silt loam, brown (7.5YR 5/3) broken face, dry; strong medium granular structure parting to strong fine granular; very friable, slightly hard, nonsticky, nonplastic; common fine, medium, and coarse and many very fine roots; 10 percent fine spherical iron-manganese concretions; 10 percent subrounded 2- to 20-millimeter gabbro gravel; strongly acid (pH 5.5); clear smooth boundary.
BA--9 to 16 inches; dark brown (7.5YR 3/4) broken face clay loam, brown (7.5YR 5/4) broken face, dry; moderate medium subangular blocky structure; friable, moderately hard, moderately sticky, moderately plastic; common fine, medium, and coarse roots and many very fine roots; common fine, medium, and coarse tubular and many very fine tubular pores; 5 percent fine spherical iron-manganese concretions; 5 percent subrounded 2- to 20-millimeter gabbro gravel; strongly acid (pH 5.3); clear smooth boundary.
Bt1--16 to 24 inches; dark brown (7.5YR 3/4) broken face silty clay loam, brown (7.5YR 5/4) broken face, dry; moderate medium subangular blocky structure parting to moderate fine subangular blocky; friable, moderately hard, moderately sticky, moderately plastic; common very fine, fine, medium, and coarse roots; common fine, medium, and coarse tubular and many very fine tubular pores; 40 percent distinct reddish brown (5YR 4/4), dry, clay films on all faces of peds and 40 percent distinct reddish brown (5YR 4/4), dry, clay films on surfaces along pores; 1 percent fine spherical iron-manganese concretions; 2 percent subrounded 2- to 5-millimeter gabbro gravel; 10 percent angular 2- to 75-millimeter moderately cemented mudstone paragravel; strongly acid (pH 5.3); clear wavy boundary. (8 to 16 inches thick)
Bt2--24 to 42 inches; reddish brown (5YR 4/4) broken face silty clay loam, yellowish red (5YR 5/6) broken face, dry; moderate medium subangular blocky structure; friable, very hard, moderately sticky, moderately plastic; few fine and common very fine and medium roots; common very fine, fine, and medium tubular pores; 40 percent distinct reddish brown (5YR 4/4), dry, clay films on all faces of peds and 40 percent distinct reddish brown (5YR 4/4), dry, clay films on surfaces along pores; 5 percent prominent black (10YR 2/1)moist, manganese coatings on ped faces; 2 percent subrounded 2- to 5-millimeter gabbro gravel; 10 percent angular 2- to 75-millimeter moderately cemented mudstone paragravel; strongly acid (pH 5.2); gradual wavy boundary.
BCt--42 to 60 inches; yellowish brown (10YR 5/4) broken face silt loam, brownish yellow (10YR 6/6) broken face, dry; weak coarse subangular blocky structure; friable, hard, slightly sticky, slightly plastic; few fine and medium and common very fine roots; common very fine and fine tubular and few medium tubular pores; 60 percent prominent clay films on all faces of peds and 60 percent prominent clay films on surfaces along pores; 5 percent prominent black (10YR 2/1)moist, manganese coatings on ped faces; 2 percent subrounded 2- to 5-millimeter gabbro gravel; 10 percent angular 2- to 75-millimeter moderately cemented mudstone paragravel; strongly acid (pH 5.2);.
TYPE LOCATION: Yamhill County, Oregon; in the northwest of the northwest of the northeast of section 4, T. 4 S., R. 5 W. Willamette Meridian. (Latitude 45 degrees, 15 minutes, 30 seconds N., Longitude 123 degrees, 18 minutes, 05 seconds W. NAD 27). Fairdale, Oregon USGA topographic quadrangle.
RANGE IN CHARACTERISTICS: The mean annual soil temperature ranges from 52 to 55 degrees F. The soils are usually moist but are dry for 45 to 60 consecutive days in all parts between depths of 4 and 12 inches following the summer solstice. The particle-size control section is 25 to 35 percent clay. The hard fragments are gabbro and the parafragments are mudstone. Reaction is strongly acid to moderately acid.
The A horizon has hue of 7.5YR or 5YR, value of 2 or 3 moist, 4 or 5 dry, and chroma of 2 or 3 moist and 3 or 4 dry. It is silt loam with 18 to 25 percent clay. It has 2 to 15 percent gravel, 0 to 10 percent cobbles, and 0 to 5 percent stones. It has 1 to 20 percent Fe/Mn concretions.
The BA or AB horizon has hue of 7.5YR or 5YR, value of 3 or 4 moist, 4 or 5 dry, and chroma of 3 to 6 moist and 4 to 6 dry. It is silt loam, clay loam, or silty clay loam with 25 to 32 percent clay. It has 1 to 25 percent gravel, 0 to 10 percent cobbles, and 0 to 5 percent stones. It has 0 to 10 percent paragravel that are moderately to weakly cemented. It has 1 to 15 percent Fe/Mn concretions.
The Bt horizon has hue of 10YR, 7.5YR, 5YR, or 2.5YR, value of 3 or 4 moist, 4 or 5 dry, and chroma of 4 to 6 moist and dry. It is silt loam, clay loam, or silty clay loam with 25 to 35 percent clay. It has 2 to 25 percent gravel, 0 to 20 percent cobbles, and 0 to 5 percent stones. It has 0 to 25 percent paragravel and 0 to 5 percent paracobbles that are moderately to weakly cemented. It has 1 to 5 percent Fe/Mn concretions.
The BCt horizon has hue of 10YR, 7.5YR, 5YR, or 2.5YR, value of 4 or 5 moist, 4 or 6 dry, and chroma of 4 to 6 moist and 6 to 8 dry. It is silt loam, clay loam, or silty clay loam with 25 to 40 percent clay. It has 2 to 30 percent gravel, 0 to 25 percent cobbles, and 0 to 5 percent stones. It has 0 to 35 percent paragravel and 0 to 5 percent paracobbles that are moderately to weakly cemented.
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Georgotte soils are on summits and side slopes of mountains at elevations of 300 to 2000 feet. Slopes range from 2 to 90 percent. The soils formed from colluvium from mudstone of the Yamhill Formation and gabbro. The climate is characterized by warm, wet winters and hot, dry summers. The average annual precipitation is 45 to 70 inches. The average annual temperature is 50 to 53 degrees F., average January temperature is 39 degrees F., and average July temperature is 65 degrees F. The frost-free period is 160 to 200 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Dixonville, Gellatly, Goodin, and Melbourne soils. The Goodin and Melbourne soils are fine; in addition Goodin soils are 20 to 40 inches to soft mudstone. They occur in areas dominated by the mudstones of the Yamhill Formation. The Dixonville and Gellatly soils are fine; in addition Dixonville soils are 20 to 40 inches to soft gabbro. They occur in areas dominated by gabbro.
DRAINAGE AND PERMEABILITY: Well drained; moderate permeability.
USE AND VEGETATION: Georgotte soils are used for forestland, wildlife habitat, recreation, and pasture. Vegetation is dominated by an overstory of Douglas fir and bigleaf maple with an understory of Cascade Oregon grape, salal, creambush oceanspray, western swordfern, baldhip rose, red huckleberry, pathfinder, common snowberry, broad-leafed starflower, and California hazel.
DISTRIBUTION AND EXTENT: Northwest Oregon. Georgotte soils are on mountains along the western margin of the Willamette Valley, Oregon. MLRA 2. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon.
SERIES PROPOSED: Yamhill County, Oregon 2004. The name is in recognition of a distinguished Oregon soil scientist.
REMARKS: The diagnostic horizons and features recognized in this pedon include:
Ochric epipedon from a depth of 0 to 9 inches (A horizon).
Argillic horizon from a depth of 16 to 60 inches (Bt1, Bt2, and BCt horizons).
Particle-size control section from a depth of 16 to 36 inches (Bt1 and Bt2 horizons).
ADDITIONAL DATA; Characterization data from NSSL Lincoln, NE for four pedons with User Pedon ID #s 04OR071006, 04OR071007, 04OR071008, and 04OR071009.