Abstract
THIS volume, which has only recently reached us, is by no means of merely local interest. The first 226 pages form a treatise on glacial geology in general, and represent the author's views after some twelve years of study of drift deposits in the field. No one who examines plates i. to vi. can mistake the character of these deposits; these excellent photographic pictures would meet, indeed, with international acceptance. On p. 30 we have some suggestive figures given as to the area of existing glaciers, from which it appears that the whole drift-covered country in North America is only ten times as large as that still covered by ice in Greenland. The Antarctic ice-sheet, moreover, is as extensive as that postulated for North America in “Glacial” times, a fact that effectually “removes the element of incredibility which, at first thought, attaches to so striking a theory as that of the glacial origin of the drift.” The northern ice, however, as Mr. Salisbury immediately points out, extended into temperate latitudes, and special explanations must thus be sought. New Jersey, we may observe, lies on the latitude of Lisbon and Sicily in the northern hemisphere, and corresponds with Cape Town and Melbourne in the southern and more glacial hemisphere. Mr. Salisbury at present seeks the cause of older widespread glaci-ations (p. 192) in Chamberlin's hypothesis of variations in the amount of carbon dioxide in the atmosphere. Elevation accelerates rock-decay, and this process promotes refrigeration by withdrawing carbon dioxide from the air. The possibility of variation in the constitution of the atmosphere, owing to the emanations of volcanoes, is also touched on as one of many other causes controlling the supply of carbon dioxide.
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C., G. Glaciation in North America . Nature 71, 186 (1904). https://doi.org/10.1038/071186a0
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DOI: https://doi.org/10.1038/071186a0