LOCATION DUMONT OREstablished Series
TAXONOMIC CLASS: Fine, kaolinitic, mesic Typic Palexerults
TYPICAL PEDON: Dumont gravelly loam, on a 25 percent east facing slope in a forested area. (Colors are for moist soil unless otherwise stated.)
Oi1--2 inches to 1 inch; loose litter of undecomposed twigs, needles, bark, and leaves.
Oi2--1 inch to 0; partially decomposed twigs, needles, bark, and leaves.
A1--0 to 4 inches; dark reddish brown (5YR 3/4) gravelly loam, reddish brown (5YR 5/4) dry; moderate fine and medium granular structure; slightly hard, friable, slightly sticky and slightly plastic; very fine to medium roots; 25 percent shot fragments; slightly acid (pH 6.4); clear wavy boundary.
A2--4 to 9 inches; dark red (2.5YR 3/4) gravelly loam, light reddish brown (5YR 6/3) dry; moderate fine and medium granular structure; slightly hard, friable, slightly sticky and slightly plastic; many very fine to coarse roots; common very fine and fine pores; 20 percent gravel; moderately acid (pH 5.8); clear wavy boundary. (Combined thickness of the A horizon is 5 to 12 inches)
BA--9 to 14 inches; dark red (2.5YR 3/6) clay loam, light reddish brown (5YR 6/4) dry; moderate to coarse granular and strong fine subangular blocky structure; hard, firm, slightly sticky and slightly plastic; common very fine to coarse roots; many very fine pores; few hard black shot and small fragments of rock; many patches of white mycelia; moderately acid (pH 5.6); clear wavy boundary. (0 to 8 inches thick)
Bt1--14 to 22 inches; dark red (2.5YR 3/6) clay loam, light reddish brown (2.5YR 6/4) dry; moderate very fine and fine subangular blocky structure; hard, firm, sticky and plastic; few very fine to medium roots; few fine and very fine pores; few fine black concretions; common faint clay films on faces of peds; few patches of white mycelia; strongly acid (pH 5.4); clear smooth boundary.
Bt2--22 to 35 inches; dark red (2.5YR 3/6) clay, reddish brown (5YR 5/4) dry; moderate medium and coarse subangular blocky structure; hard, firm, sticky and plastic; few very fine to medium roots; few fine and very fine pores; few fine concretions; few black stains; common faint clay films on faces of peds; strongly acid (pH 5.4); gradual smooth boundary.
Bt3--35 to 52 inches; dark red (2.5YR 3/6) clay, reddish brown (5YR 5/4) dry; moderate medium and coarse subangular blocky structure; very hard, firm, very sticky and very plastic; few fine and medium roots; few very fine and fine pores; few black stains; continuous distinct clay films on faces of peds and lining pores; strongly acid (pH 5.3); gradual smooth boundary.
Bt4--52 to 62 inches; dark red (2.5YR 3/6) clay, reddish brown (2.5YR 5/4) dry; strong medium and coarse subangular blocky structure; very hard, very firm, very sticky and very plastic; few very fine to medium roots; few fine and very fine pores; few soft black concretions; nearly continuous prominent clay films on faces of peds and lining pores; very strongly acid (pH 5.0); clear wavy boundary. (Combined thickness of the Bt horizon is 40 to 60 inches)
BCt1--62 to 83 inches; yellowish red (5YR 4/6) clay loam, reddish brown (5YR 5/4) dry; massive; hard, friable, sticky and plastic; few very fine pores; prominent (2.5YR 4/4) clay films in pores and on some fracture faces; very strongly acid (pH 4.7); gradual wavy boundary.
BCt2--83 to 96 inches; variegated loam, yellowish red (5YR 4/6) crushed, reddish yellow (5YR 6/6) dry; massive; slightly hard, friable, slightly sticky and slightly plastic; many very fine pores; few faint clay films in pores and distinct on some fractures; very strongly acid (pH 4.7); gradual wavy boundary. (Combined thickness of the BCt horizon is 15 to 57 inches)
C--96 to 103 inches; variegated loam, reddish brown (5YR 4/4) crushed, light reddish brown (5YR 6/4) dry; massive; slightly hard, friable, slightly sticky and slightly plastic; many very fine pores; very strongly acid (pH 4.7).
TYPE LOCATION: Douglas County, Oregon; about 1 mile north of South Umpqua Falls; 1,050 feet west and 125 feet south of the northeast corner of sec. 10, T. 29 S., R. 1 E.
RANGE IN CHARACTERISTICS: The soils are usually moist but are dry in the control section for the 45 to 60 consecutive days following the summer solstice. The mean annual soil temperature is 47 to 54 degrees F. Depth to bedrock is greater than 60 inches. Solum thickness is 40 to greater than 60 inches.
The A horizon has hue of 10YR, 7.5YR, 5YR or 2.5YR, value of 2 or 3 moist, 3 through 5 dry in the upper few inches, and 5 or 6 in the lower part, and chroma of 2 through 4 moist and dry. It has 15 to 35 percent gravel.
The Bt horizon has hue of 2.5YR, 5YR, or 7.5YR, value of 3 or 4 moist, 3 through 6 dry and chroma of 4 through 6 moist and 4 through 7 dry. It is clay or silty clay with an average of 40 to 50 percent clay. It has 0 to 10 percent gravel. It is very strongly to moderately acid.
The BCt and C horizons have variegated color. It is loam or clay loam. The underlying rocks are dominantly reddish colored. It has 0 to 10 percent gravel. It has a base saturation (sum) of 20 to 35 percent.
COMPETING SERIES: This is the Pollard series. Pollard soils are dry for 60 to 90 consecutive days.
GEOGRAPHIC SETTING: Dumont soils are on side slopes, plateaus, and broad ridgetops of mountains. Elevations are 400 to 4,000 feet. Slopes are 0 to 60 percent. The soils formed in colluvium and residuum weathered from metasedimentary or extrusive igneous rocks. The climate is characterized by hot, dry summers and warm, wet winters. The mean annual precipitation is typically 35 to 60 inches but in areas of high winter rainfall of Curry County, Oregon, may range to 100 inches. Snow falls during the winter. The mean annual temperature is 45 to 54 degrees F. The mean January temperature is 25 to 32 degrees F. The frost-free period is 100 to 200 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Acker, Coyata, and Norling series. All of these soils occur on broad ridgetops or side slopes of mountains. Acker soils are fine-loamy. Coyata soils have bedrock at 20 t0 40 inches and are loamy-skeletal. Norling soils have a paralithic contact at depths of 20 to 40 inches.
DRAINAGE AND PERMEABILITY: Well drained; moderately slow permeability.
USE AND VEGETATION: These soils are used for timber production and wildlife habitat. Vegetation is Douglas fir, white fir, western hemlock, sugar pine and ponderosa pine with an understory of dogwood, chinkapin, Pacific madrone, snowberry, cascade Oregongrape, beargrass, and whipplevine. In high rainfall areas of Curry County, areas of natural vegetation includes tanoak and canyon live oak.
DISTRIBUTION AND EXTENT: West side of central and southern Cascade Mountains and Klamath Mountains province in south western Oregon; MLRA 5. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: South Umpqua Area, Douglas County, Oregon, 1974.
REMARKS: Diagnostic horizons and features recognized in this pedon include:
Ochric epipedon
Argillic horizon - the zone from a depth of 14 to 96 inches (Bt1, Bt2, Bt3, Bt4, Bt4, BCt1, and BCt2 horizons)
Particle-size control section - the zone from a depth of 14 to 34 inches (Bt1 and upper 12 inches of the Bt2 horizon)
Pale feature - the zone from 0 to 60 inches having no decrease in clay by 20 percent
The classification was changed from Haploxerults to Palexerults in 1994.
ADDITIONAL DATA: Characterization data on 2 profiles (S59 OREG-10-1 and 10-2) reported in the Riverside Soil Survey Laboratory Report for Soils from South Umpqua Area, Douglas County, Oregon, May 1965.