Sir,

We have read with interest the letters on this subject by Mr. Law and Mr. Crary, and fully agree with their views about the need for continued revision and extension of the terms and definitions of Antarctic ice features.

Mr. Law’s illustrations of four types of island illustrate the problem well. His types (1) and (2) call for no comment, either in definition or term. However, we suggest that his remarks on types (3) and (4)

over-simplify the problem. Both types occur and need descriptive terms, but we think great confusion will arise if the term “ice island” is adopted for yet another kind of feature. “Ice island” was used widely for icebergs by visitors to the Southern Ocean during the late eighteenth and early nineteenth centuries. This usage had been dropped by about 1840, but the term was re-introduced in 1946 for the large low floating tabular bergs which have been found in the Arctic Ocean.

It seems to us that, despite its unsuitability, the latter use is now firmly established, especially in Canada and the United States. The literature on Arctic ice islands is extensive. Experience has already shown that attempts to alter this term, as suggested by Mr. Law, are unlikely to gain general agreement. It also seems essential to avoid quite different meanings in the Arctic and Antarctic.

Mr. Law considers the terms “ice rise” unsuitable for the Antarctic features which he describes (and we agree with him) but he appears to have overlooked the fact that “ice rises” are quite different from any of the features he describes. The suggested definition of “ice rise” (Reference Armstrong and RobertsArmstrong and Roberts, 1956, p. 7) is: “A mass of ice resting on rock and surrounded either by an ice shelf, or partly by an ice shelf and partly by sea and/or ice-free land. No rock is exposed and there may be none above sea-level. Ice rises often have a dome-shaped surface. The largest known is about 100 km. across.” Roosevelt Island, mentioned in Mr. Crary’s letter, is a typical example. Similar features, well in from the ice front, are very common in the area south and west of Alexander Island and in the ice shelf south and east of Thurston Peninsula on the Eights Coast. It seems, in fact, that these features are likely to be discovered and mapped in increasing numbers. The larger ones will certainly have to be given individual place-names. The problem is not confined to the Antarctic, as is shown by Reference Hattersley-SmithHattersley-Smith (1956). A more recent paper by the same author dealing with the Ward Hunt Ice Shelf in northern Ellesmere Island exemplifies the ambiguity in one sentence: “The ice island formed by the breaking away of the ice shelf in this area….” He is referring to the floating feature, not to the residual ice-covered island. An “ice rise” can, of course, become an “ice island” (in the sense proposed by Mr. Law) if the ice front breaks back far enough to leave it entirely surrounded by water. Mr. Crary also recognizes this possibility, but does not discuss the term “ice rise.”

For these reasons, we suggest that while the simple generic terms “island” and “ice rise” are sufficient for use in place-names, there is need for further terms (not to be compounded in place-names) to distinguish Mr. Law’s types of ice-covered island. There is, incidentally, at least one more distinct stage of Mr. Law’s types (3) and (4), illustrated by Reference Wright and PriestleyWright and Priestley (1922), in which the ice dome is continued out to sea by a flattened selvage of floating ice. All these are subject to temporal change, in addition to the difficulties of precise visual recognition. How, for instance, is one to distinguish between Mr. Law’s type (3) and a grounded berg of similar aspect? It is perhaps indicative that the Russians—normally addicted to fine distinctions—use only one term, ledyanaya kupola, for both “ice rise” and Mr. Law’s islands of types (3) and (4) (Reference DolgushinDolgushin, 1958). We hesitate to suggest terms, as distinct from descriptions, at this early stage of investigation. It is first desirable that others should comment on Mr. Crary’s willingness to alter the term “ice island.” If this could find general support, we think it provides the best solution.