71 58—Timbercrater-Llaorock complex, dry, 30 to 60 percent south slopes

58—Timbercrater-Llaorock complex, dry, 30 to 60 percent south slopes

 Map Unit Setting

 General location: Side slopes of mountains and ridges in the southeastern part of the park

Major land resource area (MLRA): 3

Elevation: 5,000 to 6,500 feet

Average annual precipitation: 40 to 60 inches

Average annual air temperature: 38 to 42 degrees F

Frost-free period: 0 to 50 days

 Map Unit Composition

 Timbercrater and similar soils: 50 percent

Llaorock and similar soils: 35 percent

Minor components: 15 percent

 Characteristics of the Timbercrater and Similar Soils

 Setting

 Landform: Mountain

Geomorphic position: Side slopes of mountains and buttes

Parent material: Ash and pumice

 Properties and qualities

 Slope: 30 to 60 percent; northeast to northwest aspects

Percentage of surface covered with stones and boulders: None

Restrictive features: None within a depth of 60 inches

Drainage class: Excessively drained

Crater Lake National Park, Oregon 77

Permeability: Very rapid

Flooding: Not present

Water table: Not present

Ponding: Not present

Available water capacity: About 8.1 inches

 Interpretive groups

Ecological site: Forestland—(003XY704OR) Abies/Arctostaphylos nevadensis/Carex inops

 Typical profile

 Oi—0 to 2 inches; slightly decomposed plant material

A—2 to 5 inches; paragravelly ashy loamy sand

Bw—5 to 16 inches; very paragravelly ashy loamy sand

C1—16 to 20 inches; extremely paragravelly ashy sand

C2—20 to 62 inches; extremely paragravelly ashy sand

 Characteristics of the Llaorock and Similar Soils

 Setting

 Landform: Lava flow

Geomorphic position: Side slopes of mountains and buttes

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

 Properties and qualities

 Slope: 30 to 60 percent; northeast to northwest aspects

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—(003XY704OR) Abies/Arctostaphylos nevadensis/Carex inops

 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

 Castlecrest soils

 Percentage of map unit: 10 percent

Landform: Ashflow

Geomorphic position: Ashfall and ashflow material on mountainsides

 Rock outcrop

 Percentage of map unit: 5 percent

Landform: Lava flow

Geomorphic position: Andesite lava flows on mountainsides

 Major Soil Features and Properties Affecting Management

 Timbercrater soil

 • High pumice content

• Water erosion

• Very rapid permeability

 Llaorock soil

 • Rock fragments on surface

• Rock fragments in soil profile

• Water erosion

 

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