LOCATION HOLDERMAN          OR

HOLDERMAN SERIES

TAXONOMIC CLASS: Medial-skeletal, amorphic Typic Haplocryands

TYPICAL PEDON: Holderman extremely cobbly loam - forested. (Colors are for moist soil unless otherwise noted.)

Oi--3 inches to 0; litter of charred and partially decomposing needles and twigs. (O to 3 inches thick)

A--0 to 5 inches; dark brown (10YR 4/3) and dark yellowish brown (10YR 4/4) extremely cobbly loam with black organic coatings and charcoal chips, light brownish gray (10YR 6/2) dry; moderate fine granular structure; slightly hard, friable, nonsticky and nonplastic; many very fine to coarse roots; many very fine and fine irregular pores; 40 percent gravel and 30 percent cobbles; strongly acid (pH 5.2); clear wavy boundary. (3 to 7 inches thick)

Bw1--5 to 13 inches; dark yellowish brown (10YR 4/4) and yellowish brown (10YR 5/6) extremely cobbly loam, light gray (10YR 7/2) dry; moderate fine granular structure; slightly hard, friable, slightly sticky and nonplastic; many very fine to coarse roots; many very fine irregular pores; 40 percent gravel and 30 percent cobbles; strongly acid (pH 5.4); gradual wavy boundary.

Bw2--13 to 21 inches; brown (7.5YR 5/4) extremely cobbly loam, very pale brown (10YR 7/3) dry; moderate fine subangular blocky and granular structure; slightly hard, friable, slightly sticky and slightly plastic; many very fine to coarse roots; many very fine and common fine irregular pores; 30 percent gravel and 30 percent cobbles; moderately acid (pH 5.6); clear wavy boundary. (Combined thickness of the Bw horizon is 10 to 22 inches)

C--21 to 32 inches; light yellowish brown (10YR 6/4) extremely cobbly loam, light gray (10YR 7/2) dry; massive; slightly hard, friable, slightly sticky and slightly plastic; many very fine and common coarse roots; many very fine and common fine irregular pores; 35 percent gravel, 30 percent cobbles, and 10 percent stones; strongly acid (pH 5.4); abrupt irregular boundary. (6 to 12 inches thick)

R--32 inches; fractured rhyolite welded tuff.

TYPE LOCATION: Lane County, Oregon; from a cutbank on a fire trail near the new Holderman Mountain Road; northwest 1/4 northwest 1/4, sec. 27, T. 23 S., R. 1 W.

RANGE IN CHARACTERISTICS: The mean annual soil temperature is 42 to 47 degrees F, and the mean summer soil temperature is less than 47 degrees F, when an O horizon is present. The soil is usually moist but it is dry in all parts between depths of 8 and 24 inches for less than 45 consecutive days during the summer. Depth to bedrock is 20 to 40 inches. The bedrock is hard and may be slightly to highly fractured. The particle-size control section is loam with 18 to 24 percent clay and 50 to 75 percent rock fragments. It has greater than 85 percent phosphate retention, acid oxalate extractable aluminum plus one-half iron of more than 2.0 percent, and 15 to 30 percent 15-bar moisture based on an air-dried sample.

The A horizon has hue of 10YR or 7.5YR, value of 2 to 4 moist, 4 or 5 dry, and chroma of 3 or 4. It is very gravelly loam or extremely cobbly loam. Moist bulk density is 0.65 to 0.90 grams per cubic centimeter. Organic matter is 5 to 10 percent.

The Bw horizon has hue of 10YR or 7.5YR, value of 4 or 5 moist, 6 or 7 dry, and chroma of 3 or 4 moist and dry. It is very gravelly or extremely cobbly loam and averages 50 to 70 percent rock fragments. Moist bulk density is 0.65 to 0.90 grams per cubic centimeter. Organic matter is 2 to 5 percent.

The C horizon has hue of 10YR or 7.5YR, value of 4 to 6 moist, 6 to 8 dry, and chroma of 2 to 4 moist and dry. It has 60 to 80 percent rock fragments.

COMPETING SERIES: These are the Divers, Highcamp, Kinzel, and Valsetz series. Divers soils are greater than 60 inches to bedrock and have less than 18 percent clay in the control section. Highcamp soils are 40 to 60 inches to bedrock and have less than 18 percent clay in the control section. Kinzel soils are greater than 60 inches to bedrock and have umbric epipedons 10 to 18 inches thick. Valsetz soils lack C horizons, range to 5YR within the solum, and average more than 24 percent clay in the cambic horizon (see Remarks).

GEOGRAPHIC SETTING: Holderman soils are on ridgetops and side slopes of mountains. Elevations are 3,200 to 4,700 feet. The soils formed in colluvium weathered from light colored dacitic, rhyolitic, and andesitic tuffs and breccias. Slopes are 5 to 75 percent. The climate is characterized by cold wet winters and cool moist summers. The mean annual precipitation is 70 to 100 inches, much of which falls as snow from November to May. The mean January temperature is 31 degrees F; mean July temperature is 56 degrees F; and the mean annual temperature is 43 degrees F. The frost-free period is 70 to 100 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Cruiser, Hummington, Keel, Winberry, and Yellowstone soils. Cruiser soils are deeper than 40 inches to bedrock and have less than 35 percent rock fragments in the particle-size control section. Hummington and Keel soils have an umbric epipedon 10 inches or more thick. Winberry and Yellowstone soils are less than 20 inches to bedrock. Extensive rock outcrops are commonly associated with Holderman soils.

DRAINAGE AND PERMEABILITY: Well drained; moderately rapid permeability.

USE AND VEGETATION: These soils are used for timber production. Vegetation is mainly Douglas fir, mountain hemlock, noble fir, Pacific silver fir, tall blue huckleberry, common beargrass, Pacific rhododendron, and widely spaced western white pine.

DISTRIBUTION AND EXTENT: Western footslopes of the Cascade Range of southern Lane County and northern Douglas County; MLRA 3. The series is of small extent.

MLRA OFFICE RESPONSIBLE: Portland, Oregon

SERIES ESTABLISHED: Lane County Area, Oregon, 1981.

REMARKS: This draft reflects a change in classification from Medial-skeletal Andic Cryochrepts based on the Andisol Order.

Diagnostic horizons and features recognized in this pedon:

Ochric epipedon - from 0 to 5 inches (A horizon)

Cambic horizon - from 5 to 21 inches (Bw1 and Bw2 horizons)

Particle-size control section - from 0 to 32 inches (A, Bw1, Bw2, and C horizons) with a weighted average of 69 percent rock fragments.

The separation of the Holderman series from the Valsetz series is not clear. More investigation is needed. The Valsetz soil, although recognized in both the Cascade and Coast Range was set up in the Coast Range which may result in more than 2.0 cmol/kg fine earth of 1N-KCl extractable aluminum.

ADDITIONAL DATA: Characterization data for two profiles from Lane County (S75OR-39-5 and S75OR-39-6) are available from the SCS Lincoln Laboratory.