Detailed Soil Map Units
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21—Donegan very gravelly ashy sandy loam, 30 to 65 percent south slopes
Map Unit Setting
General location: Mountainsides in the southwestern corner of the park
Major land resource area (MLRA): 5
Elevation: 4,000 to 5,100 feet
Average annual precipitation: 40 to 50 inches
Average annual air temperature: 41 to 45 degrees F
Frost-free period: 30 to 70 days
Map Unit Composition
Donegan and similar soils:
90 percent
Minor components: 10 percent
Characteristics of the Donegan and Similar Soils
Setting
Landform: Mountains
Geomorphic position: Side slopes
Parent material: Ash mixed with colluvium derived from andesite
Properties and qualities
Slope: 30 to 65 percent
Percentage of surface covered with stones and boulders: 15 percent
Restrictive feature: Bedrock (paralithic) at a depth of 20 to 40 inches
Drainage class: Well drained
Permeability: Moderately slow
Flooding: Not present
Water table: Not present
Ponding: Not present
Available water capacity: About 6.3 inches
Interpretive groups
Ecological site: Forestland—(005XY700OR) Psuedotsuga menziesii/Mahonia nervosa/Chimaphila umbellata
Typical profile
Oi—0 to 1 inch; slightly decomposed plant material
A—1 inch to 5 inches; very gravelly ashy sandy loam
Bw1—5 to 14 inches; very gravelly loam
Bw2—14 to 30 inches; extremely gravelly loam
Bw3—30 to 39 inches; extremely gravelly loam
Cr—39 to 43 inches; weathered bedrock
Characteristics of the Minor Components
Rock outcrop
Percentage of map unit: 10 percent
Landform: Lava flow
Geomorphic position: Andesitic lava flows on mountainsides
Major Soil Features and Properties Affecting Management
Donegan soil
• Steep and unstable slopes
• Rock fragments on surface
Crater Lake National Park, Oregon 43
• Rock fragments in soil profile
• Water erosion
