Published:January 01, 1979
Methods of presenting results which are used only in Part III are considered here. The simplest of these methods is virtually to copy the curves shown in the current- meter tapes, which show the continuous variation of current directions (solid line Fig. 30) and superpose on this curve dashed lines which show the approximate upvalley and downvalley directions. Above these direction plots we superpose speed in cm/sec using time intervals from 5 to 15 minutes. The direction of the flows is shown according to the magnetic compass used in our current meters. In the example included here (Fig. 30), the directions are concentrated near those of the up- and downvalley axis directtons (here 250° and 70°).
Crosscanyon flows are indicated by plotting the vectors of speed multiplied by the cosine of the angle of divergence of the current direction, from a direction thought to be normal to the axial trend of the valley (Fig. 31). Ordinarily these plots show very low velocities, but there are a few notable exceptions where currents were found to be predominantly across the valley axes, and had considerable strength.
Another method is to plot each of the vectors in a series of concentric circles with dots showing direction, 0 to 360 true, and speed indicated by distance from a central point (Fig. 32). In all cases where two vectors meet the same point only one dot is .shown, but the diagram gives a clear idea of the current direction in relation to the axis of
Figures & Tables
Currents in Submarine Canyons and Other Seavalleys
It is a widely held opinion that submarine canyons were cut during the glacial stages of low sea level and now are essentially dormant features, disturbed only on rare occasions by high-speed turbidity currents of torrential proportions. Published in 1979 after a 10-year study, this volume contradicts this concept of the canyons, with years of measurements of currents in the axes of canyons and in other types of sea valleys. It expands upon the previous publications of brief notes relative to currents measured in a few places on the deep seafloor, covering topics such as alternating current directions, turbidity currents, and crossvalley currents, clncluding with support data from studies of the California submarine canyons, British Columbia canyons, Mexican canyons, U.S. East Coast canyons, West indies canyons, Pacific Island canyons, and the Congo canyon.