Preliminary investigation of the shallow structure of the outer continental shelf and the upper continental slope has been made recently off southern and central Oregon by continuous-seismic profiling. Between Cape Sebastian and the California border, a well-developed topographic bench is present at 500-650 m. The bench has been produced by sediments which were ponded behind a gentle fold on the continental slope. Between Humbug Mountain and Coos Bay, a wedge of Quaternary sediments unconformably overlies older rocks of the continental shelf and upper slope. The Quaternary sediments appear to be absent in the area of Coquille Bank, a doubly plunging, asymmetric anticline. The straight western side of the bank appears down faulted and the benches north and south of the ban structurally controlled by the plunging anticline. Between Yaquina Bay and Cape Lookout, a series of large, north-trending folds underlie the upper continental slope. Several synclines are local basins of deposition. In this area at depths of 400-600 m a bench is present and is the surface expression of a large section of sediments which were ponded behind the first of several large folds on the upper continental slope. Small hills on the continental slope constitute the surface expression of several anticlinal folds.

End_of_Article - Last_Page 472------------