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Quartz sand grains from soils developed in superimposed deposits were studied using scanning electron microscopy. Differences in sediment provenance across lithologic discontinuities were evident by characteristic grain surface morphologies. Highly altered grains are characteristic of quartz in the Spencer Formation. Alteration and grain surface modification of quartz are at a maximum in paleosols developed from the Spencer Formation. Surface morphologic features of grains from the overlying Irish Bend Member of the Willamette Formation suggest that this deposit is composed of glacially derived material. The Greenback Member of the Willamette Formation is a mixed surficial deposit, containing sediment derived from a glacial source and local Willamette Valley provenance.
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Glasmann et al. (1980) studied this question.
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