SURFICIAL MAP CRITERIA FOR UNGLACIATED LANDSCAPES IN THE OREGON COAST RANGE: ANALOG APPLICATION FROM THE CENTRAL APPALACHIAN MOUNTAINS

A surficial mapping protocol was developed for the unglaciated, humid-mountainous region of the central Appalachians, and has direct applicability for similar landscapes in the Oregon Coast Range. The technique emphasizes the link between landforms, materials, and processes in a landscape dominated by hillslopes, mass wasting, and fluvial erosion. Three types of surficial map criteria are recognized. These include: Type I - polygonal map features associated with landforms and surficial deposits; Type II - discrete surface features not associated with surficial deposits; and Type III - observational features associated with data collection and field mapping. Type I units encompass three-dimensional landforms and deposits that result from in-situ weathering, mass wasting, fluvial processes, slope failure, and periglacial activity. Type II units include two-dimensional surface features associated with slope failure, surface hydrology, and anthropogenic activity. Type III features include scientific reference points, test pits, and soil borings used for data collection. Type I mapping criteria employ a four-fold scheme in which units are delineated on the basis of age, origin (process), landform, and material (texture). Type II and III criteria are mapped as surface features without reference to material or age. The Little River basin of Augusta County, Virginia is used as a comparative analog for application of the methodology in the Upper Nehalem Watershed, northern Oregon Coast Range. The example application suggests that a well-defined surficial map protocol combined with geographic information systems, provide useful tools for hazards assessment. The technique offers a blueprint for design of surficial maps in other unglaciated, mountainous regions.