51 38—Llaorock-Rubble land-Rock outcrop complex, 60 to 90 percent north slopes

38—Llaorock-Rubble land-Rock outcrop complex, 60 to 90 percent north slopes

 Map Unit Setting

General location: Steep side slopes, mainly of the caldera rim

Major land resource area (MLRA): 3

Elevation: 6,000 to 8,000 feet

Average annual precipitation: 50 to 70 inches

Average annual air temperature: 38 to 42 degrees F

Frost-free period: 0 to 50 days

 Map Unit Composition

 Llaorock and similar soils: 50 percent

Rubble land: 30 percent

Rock outcrop: 15 percent

Minor components: 5 percent

 Characteristics of the Llaorock and Similar Soils

 Setting

 Landform: Stratovolcano

Geomorphic position: Steep side slopes of mountains, ridges, and the caldera rim

Parent material: Ash mixed with residuum and colluvium derived from andesite

 Properties and qualities

 Slope: 60 to 80 percent; northwest to northeast aspects

Percentage of surface covered with stones and boulders: 7 percent

Restrictive features: None within a depth of 60 inches

Drainage class: Somewhat excessively drained

Permeability: Rapid

Flooding: Not present

Water table: Not present

Ponding: Not present

Available water capacity: About 9 inches

 Interpretive groups

 Ecological site: Forestland—(003XY706OR) Tsuga mertensiana/Luzula glabrata var. hitchcockii

 Typical profile

 Oi—0 to 1 inch; slightly decomposed plant material

A—1 inch to 7 inches; gravelly ashy sandy loam

AB—7 to 14 inches; very stony ashy sandy loam

Bw1—14 to 24 inches; extremely stony medial sandy loam

Bw2—24 to 61 inches; extremely stony medial sandy loam

 Characteristics of the Rubble Land

 Landform: Talus slope

Geomorphic position: Talus on side slopes of mountains, ridges, and the caldera rim

Parent material: Colluvium derived from andesite

Slope: 60 to 90 percent

 Characteristics of the Rock Outcrop

 Landform: Stratovolcano

Geomorphic position: Rock outcroppings on side slopes of mountains, ridges, and the caldera rim

Parent material: Andesite

Slope: 60 to 90 percent

 Characteristics of the Minor Components

 Timbercrater soils

 Percentage of map unit: 5 percent

Landform: Ashfall

Geomorphic position: Pumice and ashfall deposits on side slopes of mountains, ridges, and the caldera rim

 Major Features and Properties Affecting Management

 Llaorock soil

 • Rock fragments on surface

• Steep and unstable slopes

• Rock fragments in soil profile

• Water erosion

 Rubble land

 • Steep and unstable slopes

• Rock fragments

• Lack of soil material

 Rock outcrop

• Lack of soil material

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