Abstract

Time-series measurements of bottom currents on the northern Oregon continental shell reveal widely varying speeds with means near 10 cm per sec. Current direction is more constant but often is rotary. Frequency power spectra indicate that generation may be due to internal and surface tides.

Measurements of turbidity along four transects and at two time-series stations indicate that suspended material concentrates principally at the seasonal thermocline, at the permanent pycnocline, and at the bottom. Thickness and intensity of the bottom layer vary with both current strength and the amount of fine material in the surface sediment, whereas the intensity of the midwater layer appears to be related to the distance from the sediment source. The midwater layer also increases in vertical extent away from the shore. Seaward transport at the upper two surfaces provides a mechanism by which terrigenous sediment and biogeneous material bypasses the outer continental shelf.

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