The general direction of the longitudinal depression is at right angle to the 

 general direction of ice movement. Holtedahl (1958), commenting on this same re- 

 lationship in the Northern Hemisphere, suggests that valleys of considerable depth 

 may have existed prior to glaciation . 



The canyons reported by the USS STATEN ISLAND while steaming close along 

 the northern shore of Edward VII Peninsula (Profile A-B, Figs. 2 and 3) are in- ■ 

 terpreted by this writer as notches carved into the south wall of the longitudinal 

 depression by ice moving outward from the peninsula. These canyons have cross- 

 profiles typical of fjords such as those of the west coast of Norway. (In physiog- 

 raphic literature fjords are deep and narrow ice-cut channels with steep sides.) 



Holtedahl (1935) states that most typical fjords are found in a highland 

 where existence of older, river-cut valleys caused a concentration of ice erosion 

 along certain narrow zones where a bedrock of hard, jointed rocks favored the 

 development of angular design and steep walls. Holtedahl (1935) also states that, 

 if, in similar rocks, there had been no previous river erosion, but glacial erosion 

 had begun, for example, on an undissected plateau surface and its coastal slope, 

 the result is a system of relatively short and broad bays or valleys, such as found 

 on the northwest corner of Spitzbergen and the west coast of Palmer Peninsula, 

 Antarctica . 



The outcrops of Edward VII Peninsula show hard, jointed rocks whose struc- 

 tural grain is in the same approximate orientation as are the off-shore canyons. 

 Since most of these canyons of Profile A-B are deep and narrow, and yet do not 

 extend past the longitudinal depression, the application of Holtedahl 's (1935) gen- 

 eralizations suggests that the inner shelf was once eroded by rivers, whereas the outer 

 shelf was not. If this is correct, the longitudinal depression (or series of depressions) 

 marks the position of a fault zone along which the uplift of the inner shelf relative 

 to the outer shelf took place before the onset of Pleistocene glaciation . 



Wade (1937) proposed that the ice of the northeast shoreline of Sulzberger Bay 

 conceals "a magnificent fjord country." Here too, ice erosion may have been 

 guided by Tertiary river valleys . 



The broad-based canyon at the east end of Profile A-B lies directly offshore 

 of a small ice stream labeled "glacier" in Figure 5. The writer ascribes the origin 

 of this canyon to a former extension of this ice stream . 



Northeast of Sulzberger Bay, off Guest Island and Ruppert Coast areas, Byrd 

 (1933) observed and photographed thick (and therefore deep-rooted) icebergs float- 

 ing freely adjacent to the coast, but grounded farther offshore. His observation 

 opens the possibility of the existence of longitudinal depressions off these coasts. 



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