F-2 



"Cheep Tow" census presented in this report, we have made a 

 superficial survey of the geological literature of the east 

 coast submarine canyons intending to distinguish regional 

 and local faunal/substrate associations. For example/ the 

 observation of a given invertebrate does not permit the auto- 

 matic conclusion that it is related to the temperature of 

 the water alone: it could equally be present or absent in 

 response to nutrient availability, current velocity, sub- 

 strate hardness, or any combination of these. If, on the 

 other hand, a regional biological survey such as presented 

 elsewhere in this report, recognizes broad regional gradients 

 in biological populations to which each canyon contributes 

 detail, those ecologic conclusions drawn are strengthened. 



Most of the geology of continental margins has been 

 investigated by two methods: direct observation/sampling by 

 submersibles and coring/dredging operations, and through 

 acoustical surveys relying on interpretation of refraction 

 and reflection profiles. In addition to these standard 

 techniques, the canyons mapped during the field program were 

 investigated by 12kHz echo sounding along precision navigated 

 tracks. The tracks were aligned both parallel to and orthog- 

 onal to the overall canyon trend. The tracks were spaced a 

 distance equal to 50% of the local water depth of the canyon 

 in order to totally sonify the seafloor. Such echograms 

 reveal not only the gradients of the canyon walls, but the 

 complex areal distribution of the side tributaries. Addi- 

 tional bathymetry was obtained directly from the 100 km of 



