National Geographic : 1897 Apr
GEOGRAPHIC LITERATURE type. The type specimen of the piedmont glacier is the Malaspina ice sheet of Alaska, while the type for the vast continental glaciers of the ice age is found in Greenland. "'Themagnificence of the field for glacial study in North America has only been appreciated within recent years, and is still unrecognized outside of a limited circle of special students," but the recognition must extend under this forcible presentation. A student of the European Alps and the Southern Alps of New Zealand, both famed for glaciers; the explorer of several glaciers of the high Sierra; the discoverer of Malaspina glacier and the sole student of the ice-fields high on the slopes of Mount St Elias; an experienced investigator of the glacial deposits and glacial history of United States from Atlantic to Pa cific, Professor Russell is well qualified to prepare a reading lesson on glaciers, and his experience crops out between the lines on every page. Perhaps half of his admirable pictures are from photographs of his own making; and although the pronoun in the first person seldom appears, a third or a half of the descriptive paragraphs-and these make up most of the book-represent personal work. Thus the chapters have an attractive air of freshness and realness. This strong personal element, which gives the treatise its greatest value, has apparently affected the arrangement of contents, giving the work the form of a narrative rather than the sym metry of a monograph. The first chapter is an introduction, in which definitions and general features are set forth. After enumerating the "leading characteristics of glaciers," the author proceeds thus to answer the question, " What is a glacier?" "As a provisional definition, it may be said that a glacier is an ice body originating from the consolidation of snow in regions where secular accumulation exceeds melting and evapo ration, i. e., above the snow line, and flowing to regions where waste exceeds supply, i. e., below the snow line " (page 16). He then describes glacial abrasion, smoothed and striated surfaces not produced by glaciers, special features of glaciated surfaces, glacial deposits, glacial sediments, and changes in topography produced by glaciers, all with less repetition in treatment than in titles. The second chapter relates to the general distribution of the glaciers of North America, and then follow five chap ters devoted respectively to the glaciers of the Sierra Nevada, the glaciers of northern California and the Cascade mountains, the glaciers of Canada, the glaciers of Alaska, and the glaciers in the Greenland region, these chapters containing more than half the volume and most of the value of the book. There is a chapter on the climatic changes indicated by the glaciers of the Ice Age and another on the movement of glaciers, while the tenth and last chapter is a suggestive and attractive discussion of the life history of a glacier, in which the extended observations and reflec tions of the author are summarized. The strong points of the work are its vividness and trustworthiness; the arrangement might have been improved, a few trifling errors in the orthography of names might have been corrected, and the general scien tific discussion might have been strengthened, but teachers and others are to be congratulated on having at last-and for the first-a thoroughly reliable popular account of the glaciers of North America. WJM.