Portland State University. Department of Geography.
Larry W. Price
Term of Graduation
Date of Publication
Master of Science (M.S.) in Geography
Mountain soils -- Oregon -- Wallowa Mountains, Geomorphology -- Oregon -- Wallowa Mountains, Soil formation -- Oregon -- Wallowa Mountains
1 online resource (2, ix, 159 pages)
Alpine soils are young, poorly developed soils that occur above treeline. This study investigates soils located in the alpine-subalpine zone of the Wallowa Mountains, northeast Oregon. Parent material, topography, and vegetation are the most influential pedogenic factors in the high alpine landscape of the Wallowas. Soil samples were collected from the Eagle Cap Wilderness Area of the Wallowas at three mountain locations: Eagle Cap, Sacajawea, and Matterhorn. Catenas were studied in the Windblown and Minimum Snowcover zones to examine different pedogenic factors, according to the Synthetic Alpine Slope model. · Field and laboratory testing characterized the alpine soils as predominantly loamy-sands with weak structural development. The 1:1 water pH values range from 6.5 to 7.3, and the soil hues are 10YR and 2.5Y in color. Soil classification characterized Eagle Cap soils as Andisols: Lithic and Typic Haplocryands. The Matterhorn and Sacajawea residuum was not classified. Parent material influence on soil development was more noticeable on granodiorite than basalt, reflecting the propensity of granodiorite to weather rapidly. Marble and shale sites lacked soil development. All the soils exhibited eolian influence, determined from silt mineralogy results. While this component did not dominate the soils as in other alpine areas, its presence was ·proven by quartz and feldspars in soils developed on marble and calcite in soils developed on granodiorite. Sodium fluoride (NaF) pH tests indicate that there is also a high aluminum content in the alpine soils, probably due to influx of Mazama volcanic ash. Krummholz and alpine turf increase the organic content of the soil, although soils beneath krummholz were not as deep. This is partially due to decreased snowcover, subsequent lack of moisture, and different parent material. All soils show a decrease in organic carbon with depth indicating that bioturbation was either low, or the soil recovered from the disturbance rapidly. Organocutans found on the bottom of rocks in the B horizon illustrate organic trans location. The increase in pH with depth shows the influence of surficial organic matter, translocated dusts, and ash. Nunatak and landmass influence on soil development was undetermined.
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Allen, Charles Edward, "Alpine Soil Geomorphology: The Development and Characterization of Soil in the Alpine-Subalpine Zone of the Wallowa Mountains, Oregon" (1996). Dissertations and Theses. Paper 5217.