Detailed Soil Map Units
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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
