22 9—Castlecrest-Llaorock complex, 2 to 25 percent slopes

Soil Survey of Crater Lake National Park, Oregon

Detailed Soil Map Units

9—Castlecrest-Llaorock complex, 2 to 25 percent slopes

Map Unit Setting

General location: Mountainsides

Major land resource area (MLRA): 3

Elevation: 5,500 to 6,500 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

Castlecrest and similar soils: 60 percent

Llaorock and similar soils: 25 percent

Minor components: 15 percent

Characteristics of the Castlecrest and Similar Soils

Setting

Landform: Ashflow

Geomorphic position: Mountainsides

Parent material: Ash and pumice

Properties and qualities

Slope: 2 to 25 percent

Percentage of surface covered with stones and boulders: None

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 6.3 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 3 inches; paragravelly ashy loamy sand

Bw—3 to 19 inches; paragravelly ashy loamy sand

C1—19 to 26 inches; ashy sand

C2—26 to 38 inches; ashy coarse sand

C3—38 to 64 inches; ashy coarse sand

Characteristics of the Llaorock and Similar Soils

Setting

Landform: Stratovolcano

Geomorphic position: Side slopes of mountains and ridges

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

Properties and qualities

Slope: 2 to 25 percent

Percentage of surface covered with stones and boulders: 3 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 Minor Components

Grousehill soils

Percentage of map unit: 8 percent

Landform: Ground moraine

Geomorphic position: Glacial moraines on mountainsides and in valleys

Sunnotch soils

Percentage of map unit: 4 percent

Landform: Debris flow

Geomorphic position: Debris flows on mountainsides

Rock outcrop

Percentage of map unit: 3 percent

Landform: Lava flow

Geomorphic position: Andesitic lava flows on mountainsides

Major Soil Features and Properties Affecting Management

Castlecrest soil

• Sandy textures

• Low soil strength

• Dustiness if vegetation is removed

Llaorock soil

• Rock fragments on surface

• Rock fragments in soil profile

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