AN ABSTRACT OF THE THESIS OF

A framework is presented for a more causal explanation and ordering of stream characteristics than traditional means have used. Patterns of stream habitat distribution are related to particular characteristics of the geomorphology of watersheds. Variability in stream characteristics can be explained by the spatial distribution of properties of the watershed and by identifying stages in the development of stream habitat. This has implications for the classification of streams in a geomorphic context, emphasizing the concepts of capacity and genesis. Within the context of a hierarchical watershed classification, stream segment is considered the most useful classification level for understanding habitat distribution and dynamics. Basins in basalt and sandstone geologic formations in the Oregon Coast Range were investigated for stream habitat distribution. In streams flowing through sandstone, repetitive patterns of large-scale valley segments are identified in headwaters to large rivers. Segment boundaries are identified by changes in valley morphology. Alternating patterns of wide valleys and constricted valleys are common in some landtype associations. The formation of thes