Cryoplanation terrace orientation in Alaska

Exploratory analysis of the orientation of 303 cryoplanation terraces in in terior and western Alaska lends tentative support to the hypothesis that th ese landforms develop through localized erosion related to spatial patterns of snow accumulation and ablation. Cryoplanation terraces exhibit orientat ion patterns similar to those of cirques in several regions of Alaska. In c limatically continental east-central Alaska, cryoplanation terraces are dev eloped preferentially on north-facing slopes and the frequency distribution of terrace orientation is similar to but less concentrated than that of gl acial cirques. In south-central Alaska, both cirques and terraces have bimo dal frequency distributions corresponding to generalized wind patterns that predominated during Pleistocene glaciations. In western Alaska, terraces a nd cirques have relatively diffuse patterns without preferred orientation. No clear relation is apparent between the orientation of cryoplanation terr aces and their size or elevation, although this may be an artifact of the c urrent inability to differentiate terraces by age. Data from the Eagle Summ it/Mastodon Dome area in interior Alaska indicate a possible relation betwe en snowline elevation and the concentration of terrace orientation.