Abstract

In response to the progradation of the Washington continental slope and uplift of sediment at the eastern edge of Cascadia Basin, Cascadia Channel has altered its course by migrating seaward where the channel leaves the base of the slope and passes through the swale between Nitinat and Astoria submarine fans. Long-range side-scan sonar and acousticreflection data reveal a series of descending terraces, averaging 3 km in width and 10 m in height, between the base of the slope and Cascadia Channel that evince the lateral migration of the channel. Cascadia Channel, in this specific case, has responded as a terrestrial fluvial system does to tectonic tilt.

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