1 Lydonia, which seems to have both erosional and depositional 



2 environments. 



3 It's unclear, really, from the available data, what the other 



4 canyons are like there. That suggests, I think, a problem with the--at 



5 least we need to consider the erosional and depositional classifications 



6 of canyons that was proposed in the two hypotheses which we've been 



7 presented. 



8 It may be that we have more of a continuum, I think erosional and 



9 depositional is a good way to think about it, but there may be a 



10 continuum--there obviously is a continuum between erosional and 



11 depositional environments in the canyons that we've looked at so far. 



12 Thank you. 



13 DR. TEAL: You have a hypothesis for the difference between 



14 Lydonia and Oceanographer? 



15 DR. BUTMAN: About why they're so different? 



16 DR. TEAL: Yes. 



17 DR. BUTMAN: Only a working hypothesis. 



18 DR. TEAL: Fine. 



19 DR. BUTMAN: I think that the strength of the currents is a 



20 function of the bottom slope of the walls of the canyon and the bottom 



21 slope. The density stratification, which is imposed on the outer part 



22 of the canyon by the deep-ocean circulation, and those control the 



23 propagation of the high-frequency energy which we saw and I think that 



24 there are several theories for it. It's hard to describe in a few 



25 minutes. 



26 The propagation of energy both into the canyon and up the canyon 



27 axis depends on the bottom slope and the density distribution. I think 



28 there is a complex interaction between those, which in some canyons 



29 intensifies the flow near the bottom, and in some cases energy won't be 



30 allowed to propagate up the canyon axis and intensify near the head. 



31 In other cases, for particular combinations of bottom slopes and 



32 density distributions, the energy will be reflected back out of the 



33 canyon. I think that is what we're seeing in the difference between 



30 



