V. CONCLUSIONS 



The writer's conclusions as to the geologic origins of the submarine topography 

 of the eastern Ross Sea and Sulzberger Bay are summarized below: 



A . The outstanding feature of the outer surface of the continental shelf of 

 the Sulzberger Bay area 1$ its great depth of 200 to 300 fathoms . The depth of 

 this terrace is probably due to remnant crustal downwarp caused by ice-loading 

 during the last glacial maximum when the grounded Antarctic Ice sheet advanced 

 to the shelf break. Glacial compaction, erosion, and paucity of Pleistocene 

 sedimentation played lesser parts in the lowering of the outer shelf surface. 



B. A 600-fathom trough extends from under the shelf ice of Sulzberger Bay 

 toward the outer edge of the continental shelf. The origin of this transverse de- 

 pression is ascribed to glacial erosion along a major fault zone by an Ice stream 

 during glacial maxima. 



C . Longitudinal depressions are found parallel to shore and along-side the 

 relatively shallow inner shelf terrace which borders the shore. The longitudinal 

 depressions have probably been carved by sub-freezing ice sheets along zones of 

 less resistance. These zones are parallel to the general trend of the shore line 

 and may represent major fault zones, change in lithology, or narrow zones of 

 crustal movement. 



D . The inner shelf represents rocks more resistant to erosion and/or Is the 

 upthrown block along the shore side of a fault zone marked by the longitudinal 

 depressions . 



E. Longitudinal ridges border the outer edges of the longitudinal depressions. 

 These longitudinal ridges appear to be morainal in nature and may be, at least in 

 part, composed of material scooped out of the longitudinal depressions by former 

 grounded, sub-freezing sheets . 



F. The transverse ridge which extends north from Cape Colbeck may be o 

 lateral moraine or a medial moraine deposited between two units of the continental 

 ice sheet when the ice extended to the shelf break. 



G . The transverse ridge which extends west from Edward VII Peninsula may 

 be the remnant of an end moraine formed by a grounded Ross ice sheet during a 

 former stand . 



In summary, the author concludes that the gross bathymetric features of the 

 continental shelf of the eastern Ross Sea and Sulzberger Bay have been formed by 



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