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
