topographic expression and structural axes of the Edsel Ford Mountains and the 

 Alexandra Mountains on either side of this line also trend NW-SE. 



The writer suggests that the transverse depression of Sulzberger Bay is the 

 result of structurally controlled erosion along a major fault zone by an ice stream 

 during periods of glacial maxima . 



2. Longitudinal Depressions and the Inner Shelf. The longitudinal depression 

 and its bordering inner shelf parallel to the north shore of Edward VII Peninsula 

 (Fig. 2) seems to be similar to the "inner shelf depressions" and "hilly shelf" off 

 East Antarctica described by Zhivago and Lisitzyn (1957) and to the longitudinal 

 depressions and inner shelves off Norway, Labrador, and Alaska described by 

 Holtedahl (1958). 



Zhivago and Lisitzyn (1957) suggest that the longitudinal depressions off East 

 Antarctica were caused by a major fracture at the edge of the continent which occurred 

 as a result of vertical movements of the mainland. Zhivago and Lisitzyn (1957) relate 

 the vertical tectonic movements of the mainland with changes in its glacial load, and 

 point out that the primary disjunction of forms is only slightly leveled by marine 

 sedimentation . 



Holtedahl (1958) suggests that the longitudinal channels along glaciated coasts 

 of the Northern Hemisphere represent major crustal fracture zones, with a down- 

 drop of the outer, deeper shelf relative to the inner shelf. He points out that, to 

 account for the great depressions as being formed by ice erosion, one would have 

 to assume that this outer part of the shelf consists of rocks very different in litho- 

 logic character from those of the inner shelf area - viz., either very soft rocks or 

 with a great concentration of fractures . 



Shepard (1948) suggests that glacial erosion of the sea floor may have been 

 more effective than erosion within the continent because the rock of the continen- 

 tal shelves appears to be softer, in general, than that of the continental masses. 

 Holtedahl (1958) points out that, even on this assumption, the abrupt drop from 

 the level of the inner shelf at a depth less than 100 fathoms (off Labrador, in this case) 

 to the inner deep of the transverse depression at a depth of over 450 fathoms over 

 a distance of about five kilometers seems to suggest factors other than ice erosion 

 contributed to its formation . 



Off Edward VII Peninsula, the depth drops from 130 fathoms to over 600 fathoms 

 over a distance of as little as one mile (Fig . 5 and the southwest end of Profile 

 C-D, Figi. 2and3). 



22 



