1 So, the canyons, at least based on this analysis, are much more 



2 energetic than the adjacent slope. Those energetic currents cause 



3 intense sediment resuspension along the axis in Lydonia Canyon. 



4 I'd just like to show that from some hydrographic data. I'll show 



5 you the light transmission or beam attenuation profiles from three 



6 stations in the axis of Lydonia Canyon and compare that to the adjacent 



7 shelf and the adjacent slope. 



8 Beam attenuation is, under some assumptions, directly proportional 



9 to suspended matter concentration. The solid lines are the stations in 



10 the canyon axis, the dotted lines are the stations in the slope, and the 



11 dashed lines are the stations on the shelf. 



12 First, the suspended-matter concentrations are always higher in 



13 the canyon than over the adjacent slope at comparable depths. At all 



14 stations within the canyon axis, we see increased suspended sediment 



15 concentrations near the bottom, particularly near the canyon head, in 



16 depths of 200 to 300 meters. 



17 This is in that area of fine-grained sediments, and we attribute 



18 this to resuspension by the strong bottom currents there. 



19 I could show you other examples of that, but this is a good 



20 typical one, where we see essentially a tranquil slope, resuspension in 



21 the axis of the canyon, resuspension decreasing at depths deeper in the 



22 canyon, and also some resuspension on the adjacent shelf. 



23 Dick alluded to the fact that currents change dramatically within 



24 the canyon, and this is just a 10-day period record of temperature, beam 



25 attenuation (again proportional to suspended sediment concentration), 



26 bottom current speed, and up- and down-canyon flow of one station near 



27 the bottom in the head of Lydonia Canyon. 



28 I call your attention first to the beam attenuation where we see 



29 changes of over two beam attenuation units, which is probably at least 5 



30 to 10 mg/1 on a daily basis. We see major increases in suspended 



31 sediment concentration over very short periods of time. 



32 We see very rapid changes in the bottom current speed from near 



33 to greater than 40 cm/sec in a period of a few hours. We see also both 



34 up-canyon and down-canyon flow. At least in the head of Lydonia Canyon, 



28 



