INTRODUCTION Of all Antarctic glacial features, none is as characteristic or as distinctive and none has excited as much interest and as much speculation from explorers, as the areas of shelf ice which occupy protected or partly protected areas about the continent. The best known and largest of these is the Ross Shelf Ice, which extends northward from the head of Ross Sea approximately 500 miles at its broadest part and whose seaward margin is 100 miles greater (Pl. 111). The expression, Ross Barrier or Ross Ice Barrier, has held a secure place in Antarctic literature too long to be completely abandoned, even though it is by no means as descriptive as the term Ross Shelf Ice. The latter term is used in this paper to include the whole mass, and Barrier or Ross Barrier identifies only the northern face or escarpment (Fig. 1). It was this wall of snow-ice . . .