II . BATHYMETRY OF EASTERN ROSS SEA AND SULZBERGER BAY 



The morphological features of the eastern Ross Sea and Sulzberger Bay shown 

 In Figures 2 through 5 can be classified as: (1) the outer shelf, (2) the inner shelf, 

 (3) the shelf depressions, and (4) the shelf ridges. 



A. Outer Shelf 



The outer shelf (Fig. 2), the deep-lying terrace of the continental shelf, 

 ends abruptly at between 210 and 280 fathoms below sea level where the steep 

 (approximately 100 fathoms per mile) continental slope marks the beginning of 

 the Pacific Antarctic Ocean . The outer shelf slopes gently toward land from the 

 shelf edge, and the average depth of the flatter portions is about 300 fathoms . 

 This inward tilt is especially evident in the Ross Sea where the shelf is relatively 

 smooth (Profile C-D, Fig. 3). 



B. Inner Shelf 



The inner shelf (Fig. 2), so designated in text after Holtedahl (1958) 

 who observed similar features, is a narrow, relatively shallow, hilly terrace that 

 borders the shores of Edward VII Peninsula. The depths of this dissected terrace 

 range from 115 to 200 fathoms. Across its flatter parts, its depth is 130 fathoms 

 (Profile A-B, Fig. 3), and It is about 200 fathoms shallower than the flatter portions 

 of the outer shelf (compare Profiles A-B, C-D, and G-H, Figs . 3 and 4) . Off 

 CapeColbeck, the inner shelf narrows to one mile, but it broadens as it rounds the 

 peninsula until it is 15 miles wide in Sulzberger Bay. The outer edge of this shelf 

 is abruptly terminated by the shelf depressions. 



C . Shelf Depressions 



Shelf depressions (Fig. 2), great troughs within the continental shelf, are 

 found close to shore . The depth Profile A-B (Fig . 3) shows a series of deep, steep- 

 walled, fjord-like canyons cut Into the Inner shelf, and a 5-mile-wide canyon 

 with a jagged floor at 730 to 860 fathoms . The slopes of the steep canyon walls 

 appear to exceed 30** In several places where the profiles show a vertical relief 

 of up to 500 fathoms within one or two miles. 



An east-west-trending canyon Is shown on Profile G-H (Fig. 4). This narrow, 

 800-fathom canyon Is bordered on its seaward side by the outer shelf and on its 

 shore side by the inner shelf. This east-west depression, parallel to the north shore 

 of Edward VII Peninsula, is referred to as the longitudinal depression after 

 Holtedahl 's (1958) description of similar depressions off other glaciated coasts. 



