Cascadia channel is the most prominent and extensive deep-sea channel known in the northeastern Pacific Ocean. Preliminary results from a survey of this channel in the part of Cascadia abyssal plain off the Oregon coast and in the seamount province west of the plain are presented.

The bottom of the channel has a depth range of 1,565-1,830 fathoms and a slope of about 1:1,000. Relief ranges from 20 fathoms off northern Oregon to more than 400 fathoms in an abyssal gap in the seamount province. The width of the channel ranges from 1 to 4 nautical miles at the top and from less than ¼ to about 3 miles at the bottom.

Piston cores taken along a 6-mile profile extending from the western side (abyssal plain) to the eastern side (Astoria fan) of Cascadia channel exhibit a marked diversity in sediment texture and composition. On the western side the sediments are composed chiefly of gray clay interbedded with thin laminations of sandy silt. Planktonic Foraminifera predominate in the sandy material. Sediments in the axis of the channel consist of several cyclic depositional units. Each unit is made up of a basal fine sand grading upward into olive-brown silt and clay and overlain by gray clay. The sand and silt contain detrital minerals and organic debris derived from continental sources. On the eastern side the sediments are similar to terrigenous material found elsewhere on Astoria fan.

Sedimentation on Cascadia abyssal plain is controlled, to a large extent, by Cascadia channel. The channel apparently acts as a sediment trap and as an avenue of dispersal for terrigenous material transported along the sea floor.

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