1 DR. VALENTINE: I think the walls of the canyons may be 



2 characterized as areas where sediment is either being eroded by bio- 



3 erosion, say, or is in transit. The question is: How long does it take 



4 to move down the walls towards the floor? 



5 DR. BUTMAN: You say it is in transit because it is mainly sand? 



6 DR. VALENTINE: It is sand and silt mixed. The shelf sand becomes 



7 mixed with the bio-eroded-- 



8 DR. BUTMAN: What is the evidence that it is in transit, though? 



9 DR. VALENTINE: Well, the evidence would be ripples, ripple marks, 



10 accumulation of the bio-eroded material on the canyon floor. 



11 DR. BUTMAN: I guess from the limited dives I did in Lydonia 



12 Canyon, I didn't see any ripple marks in the canyon walls in the places 



13 that I dove. I think that that may be true in Oceanographer Canyon, but 



14 not necessarily true otherwise. 



15 DR. VALENTINE: The walls are not uniformly rippled. They are 



16 patchy, but I think you would have to-- 



17 DR. HECKER: There are patches of ripples deep in Lydonia Canyon, 



18 patches on the walls. 



19 DR. COOPER: I've seen rippled areas in a number of Lydonia Canyon 



20 walls, especially in some of the little tributaries. 



21 DR. BUTMAN: I agree that there are some places there are and some 



22 places there aren't. 



23 DR. VALENTINE: It might be depositional for long enough for a 



24 layer of fine grained material to have an effect, conceivably. 



25 DR. GRASSLE: What is the toxicity effect? 



26 DR. BUTMAN: I just don't want to give the impression that 



27 everywhere in the canyon it is violently being mixed every 5 minutes so 



28 that anything that settles there is immediately resuspended and 



29 transported. 



30 There are some areas which, over long time scales are probably 



31 fairly tranquil, so I could see possibly chemical or physical effects of 



32 a layer of drilling mud changing settlement, but not for a long period 



33 of time. 



311 



