ROUNDTABLE DISCUSSION: 



SUMMARY AND SYNTHESIS 



GEOLOGY AND GEOCHEMISTRY OF NORTH ATLANTIC SUBMARINE CANYONS 



Dr. Bradford Butman, Chairperson 



U.S. Geological Survey 



Woods Hole, MA 



Fonowing the first day's scientific presentations, a roundtable 

 discussion of existing information on submarine canyons was held with an eye 

 toward producing a consensus summary document. The focus for consensus was to 

 be on mechanisms and not necessarily impacts. Agreement on mechanisms is 

 necessary to assess potential impacts of drilling from routine operations and 

 discharges, accidental spills, and "worst case" events. 



GENERAL DESCRIPTION OF CANYONS 



The submarine canyons that incise the southern margins of Georges Bank 

 vary in size, shape, and length. In some cases, they extend for long 

 distances past the shelf break onto the continental slope. Studies have been 

 conducted both in shallow- and deep-water parts of the canyons (see background 

 papers given on Day 1 of the workshop). These studies have shown that canyons 

 exhibit widely different sedimentary environments. Characteristics which 

 differ from canyon to canyon include sediment texture, bottom currents, and 

 intensity of erosional and depositional processes. 



The workshop conclusions focus on the shallow parts of the canyons,* 

 defined as the area from the canyon head to the point where the canyon crosses 



"See also reviewer comment in Appendix A. 



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