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Postglacial History of the Bowhead Whale and of Driftwood Penetration: Implications forPaleoclimate, Central Canadian Arctic by Arthur S. Dyke; Thomas F. MorrisReview by: John J. ClagueArctic and Alpine Research, Vol. 25, No. 3 (Aug., 1993), pp. 258-259Published by: INSTAAR, University of ColoradoStable URL: http://www.jstor.org/stable/1551825 .

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will see it as a model for a more substantial, commercially pro- duced book in the future.

JOHN D. JACOBS

Department of Geography Memorial University of Newfoundland St. John's, Newfoundland, AIB 3X9 Canada

POSTGLACIAL HISTORY OF THE BOWHEAD WHALE AND OF

DRIFTWOOD PENETRATION: IMPLICATIONS FOR PALEOCLIMATE, CENTRAL CANADIAN ARCTIC. By Arthur S. Dyke and Thomas F. Morris. (Geological Survey of Canada Paper 89-24.) Ottawa: Geological Survey of Canada, 1990. iv + 17 pp. $5.00 plus 30% additional for orders outside Canada. ISBN 0-660-13719-4.

POSTGLACIAL TECTONIC AND SEA LEVEL HISTORY OF THE CENTRAL

CANADIAN ARCTIC. By Arthur S. Dyke, Thomas F. Morris, and David E. C. Green. (Geological Survey of Canada Bulletin 397.) Ottawa: Geological Survey of Canada, 1991. vi + 56 pp. $6.75 plus 30% additional to orders outside Canada. ISBN 0-660- 14051-9.

QUATERNARY GEOLOGY OF PRINCE OF WALES ISLAND, ARCTIC CANADA. By Arthur S. Dyke, Thomas F. Morris, David E. C. Green, and John England. (Geological Survey of Canada Memoir 433.) Ottawa: Geological Survey of Canada, 1992. x + 142 pp., 3 maps, 1 erratum. $32.50 plus 30% additional for orders outside Canada. ISBN 0-660-14408-5.

These three fine papers, published by the Geological Survey of Canada between 1990 and 1992, are the culmination of several years of regional Quaternary geologic studies in the central Ca- nadian Arctic by Arthur Dyke (GSC) and graduate students of John England (University of Alberta). From the titles, the papers might seem disparate, but in fact they are closely related and can be considered a set.

The core paper (GSC Memoir 433) describes in detail the surficial deposits and landforms of Prince of Wales Island, a large (38,000 km2) island located near the center of the Canadian Arctic. The surficial geology information is displayed effectively on two, 1:250,000-scale, color maps that accompany the report. Large landscape elements (e.g., megaflutes, ribbed moraine fields), some visible only on satellite images, are explained in terms of late Pleistocene glacial history; others (stepped planation sur- faces) are attributed to much older events that predate the for- mation of the Arctic archipelago. The authors recognize three phases of ice flow across the island and relate them to the evo- lution of the Laurentide Ice Sheet during the last glaciation. They reconstruct the changing thermal regime at the base of the ice sheet from the characteristics and cross-cutting relationships of the various till landform assemblages. Other sections of the re- port deal with land-use issues (e.g., granular resources, perma- frost and ground ice, coastal zone processes) and economic ge- ology.

The paper, although well written and well illustrated, is complex and cannot be read casually; the exhaustive detail on landforms, sediments, and till composition tends to mask im- portant ideas and observations. In fairness to the authors, how- ever, it must be said that GSC memoirs are designed to provide full documentation of the geology of an area for a wide range of potential users; they are thus fundamentally different in concept from most other monographs and books.

Two topics, mentioned only incidentally in Memoir 433,

are fully developed in the other papers of the set. GSC Bulletin 397 documents the postglacial sea-level history of the central Canadian Arctic, with emphasis on Prince of Wales Island, Som- erset Island, and Boothia Peninsula. Twenty-eight emergence curves, based on almost 300 radiocarbon ages, are used to con- struct a set of isobase maps showing the amount of elevation of the crust over various periods of time. The isobase patterns demonstrate that postglacial rebound, which might be assumed to be closely related to glacier retreat, was complicated by re- activation of large regional structures, notably the Boothia Arch, during the early Holocene. The authors revive a hypothesis, originally proposed by Tozer and Thorsteinsson (1964: 219- 220), of Holocene "block tectonics," wherein postglacial re- bound of the Arctic archipelago was accompanied by differential movements of a mosaic ofblocks, some ofwhich tilted but others did not.

These findings have important implications for crustal structure, postglacial seismicity, and ice-sheet reconstruction. Many Quaternary geologists have based their reconstructions of the Laurentide Ice Sheet on postglacial shoreline deformation data. However, the mismatch between glacial history and sea- level history documented in this paper suggests that this practice may be ill-advised. This lends force to John Andrews's plea of more than a decade ago that interpretations of the configuration of former ice sheets be based on direct glacial geologic evidence (e.g., striae, glacial deposits), rather than indirect evidence such as shoreline data.

The third paper (GSC Paper 89-24) in the set documents driftwood penetration and the former summer range of the bow- head whale (Balaena mysticetus) in the central Canadian Arctic using radiocarbon-dated fossils from Prince of Wales and Som- erset islands. This is by no means an intellectual curiosity, be- cause the distribution of bowhead whale fossils has profound implications for Holocene climate change in the Arctic. The authors show that there were two periods during which bowheads were present in the central Arctic (11,000-8500 BP and 5000- 3000 BP); these were times when interisland channels were large- ly free of ice during summer. The lack of significant driftwood penetration during the earlier period is attributed to a meltwater- driven oceanographic circulation pattern that created continuous outflow from the archipelago. The arrival of driftwood and ex- clusion of bowheads from the channels at about 8500 BP indi- cates the establishment of an oceanographic circulation pattern similar to that oftoday. Major moraine deposition (the Cockburn event) between 9000 and 8000 BP occurred at the end of the open water period; subsequent slow retreat from these moraines resulted from aridity accompanying the expansion of sea ice, rather than warming.

What makes this paper particularly enlightening is the au- thors' use of a variety of seemingly unrelated data sets to identify changes in climate that have occurred in the Arctic during the Holocene. They demonstrate that certain common assumptions, such as ice retreat equals warmer climate, and absence of drift- wood equals severe ice conditions, are not valid and lead to mutually contradictory conclusions about past climate.

A few words about the physical properties of the papers: Each is 22 x 28 cm in size and has an attractive cardstock cover. Memoir 433 and its accompanying maps are packaged in a sep- arate sleeve. The text and figures are laid out in a two-column format. The print is easy to read and the figures, with the ex- ception of a couple of photographs, are clear. There are few typographic errors, aside from two instances of missing and re- peated text in Bulletin 397. Memoir 433 contains several ster- eopairs that were reduced when printed, making it difficult to

258 / ARCTIC AND ALPINE RESEARCH

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view them properly. However, a separate set of the stereopairs, at original size, is included as an erratum.

I recommend these papers to all geologists and geographers interested in the Laurentide Ice Sheet. They contain a wealth of information about the Quaternary geology of Prince of Wales Island, one of the remotest areas on the continent. More im- portantly, they are excellent examples of quality science. The observations are sound, and the ideas, although in many in- stances unconventional, are well argued and have implications far beyond the study area. Finally, they illustrate the value of Quaternary mapping. Mapping is eschewed by many geologists because of the large investment in time and resources that must be made and because it is perceived by some as an antiquated or mundane scientific activity. However, it is careful mapping such as this, conducted over a period of many years, that has provided Arthur Dyke and his colleagues with the big-picture perspective necessary to make contributions on subjects as di- verse as bowhead whales, subglacial thermal regime, and crustal deformation.

Reference Cited Tozer, E.T. and Thorsteinsson, R., 1964: Western Queen Eliz-

abeth Islands, Arctic Archipelago. Geological Survey of Can- ada Memoir, 332. 242 pp.

JOHN J. CLAGUE

Geological Survey of Canada 100 West Pender St. Vancouver, B.C., Canada V6B IR8

THE LAST INTERGLACIAL-GLACIAL TRANSITION IN NORTH AMERI- CA. Edited by Peter U. Clark and Peter D. Lea. (Geological Society of America Special Paper 270.) Boulder, Colo: Geological Society of America, 1992. vi+ 317 pp. $62.50. ISBN 0-8137- 2270-5.

The major focus of this volume is the interglacial-glacial transition of about 122 to 64 ka as recorded by landforms and sediments of former ice sheets or alpine glaciers from the Great Basin through the Canadian Arctic and from the Olympic Moun- tains to New England (14 chapters). Reviews of pluvial lake formation in the southwest also add an important climatic base- line (2 chapters) as do introductory reviews and papers on the marine record and on climate modeling (5 chapters). The volume is an outgrowth of a symposium of similar name convened by Clark and Lea at the 1988 Annual (Centennial) Meeting of the Geological Society of America in Denver, Colorado.

Perhaps more than anything else, this contribution as com- pared to others (e.g., Sibrava et al., 1986) helps summarize and upgrade existing knowledge of a geographically diverse set of North American continental records for a critical interval of geologic time. For the most part, the interval covered is one where great precision in chronological dating of the transition to Earth's ultimate glaciation has been elusive. Special Paper 270 is dedicated by its editors to Richard Goldthwait, a pioneer Friend of the Pleistocene. His view of some Upper Pleistocene stratigraphies and the concept of the early Wisconsin was com- pleted for this volume before his death in 1992. It follows a brief introduction to Special Paper 270 by Clark.

The marine oxygen isotope record, the Milankovitch orbital cycles and, to a lesser extent, uranium-series dating of coastal deposits help form the major framework for the timing and extent of glacier growth on continents; hence they form appro- priate background chapters for this volume. Mix assures us that

the astronomically tuned marine isotope ages given for stages 5e through stage 4 are within a few thousand years of true ages; however, he notes that the state of 80 understanding does not yet allow us to distinguish differences in the magnitude of ice growth events at stages 5e/5d and 5/4. So too, Muhs concedes that whether the "Sangamon" interglacial extends through sub- stage 5e or the whole of stage 5 is still unsettled. Peteet et al. emphasize the frustration of trying to model the initiation of late Wisconsin ice sheets through Milankovitch forcing. They note that resolution of the response of the atmosphere-ocean-bio- sphere-cryosphere to orbital forcing awaits improvement in the chronological resolution of the paleoclimate record.

And what of the main focus of Special Paper 270 - the North American glacial record? A theme recurring through most papers is a skepticism with radiocarbon ages beyond five or six half- lives. However, the resulting frustrations due to a lack of precise numerical dating methodology for the last interglacial to glacial transition has been partly compensated for by a wider use of aminostratigraphy, U/Th disequilibrium dating, thermolumi- nescence, electron spin resonance, or just more sophisticated relative dating techniques. For example, see Canadian studies in chapters by Stea et al., Lamothe et al., or Thorleifson et al. These techniques, when applied to the stratigraphic record be- yond the limit of late Wisconsin Laurentide Ice Sheet in the continental United States, indicate that most deposits once as- signed early or middle Wisconsin ages (isotope stages 5 or 4; e.g., see Black et al., 1973 ) are probably of Illinoian or late Wisconsin age. Chapters by Curry and Follmer, Miller et al., Szabo, Dreimanis, Eyles and Williams, and Oldale and Colman include such revised correlations. That alpine glaciers react dif- ferently to temperature signals is shown by the data of Coleman and Pierce. In half of the areas studied by them in the western United States, early Wisconsin glaciers were more extensive than those of the late Wisconsin. Not surprisingly, little is known of the early Wisconsin mountain glaciation in the arid Great Basin reviewed by Oviatt and McCoy. In more maritime areas of northern Washington and in British Columbia reviewed by Cla- gue et al., the early advances of the Cordilleran ice tongues have at least equaled those of late Wisconsin time. The proposed extent of the late Sangamon-early Wisonsin ice sheet in western Arctic Canada areas studied by Vincent, as well as the early ice sheet extent in the east Canadian Arctic and northwest Green- land, covered by Miller et al., far exceeded the glacier area of the acknowledged late Wisconsin in these locations. For the Baffin Bay areas, Miller et al. note that the warmer and wetter land and warmer sea surface temperatures in late stage 5 fostered ice sheet growth, while the ice was limited by the colder and drier climate of stage 2.

Is there more to Special Paper 270? Yes, there is. For ex- ample, the clear (albeit brief) revision of the classic Willman and Fry (1970) Sangamon-Wisconsinan and Wisconsinan/Farmda- lian-Woodfordian successions of Illinois by Curry and Follmer and the careful field definition of till in the Sunnybrook drift of Toronto by Hicock and Dreimanis. There are the paleoecological analyses of Clague et al. and of Bachhuber, and the detailed directional analysis of glacier movements in the Hudson Bay lowland by Thorleilson et al. to mention but a few examples. The brief update of paleolimnologic records of the Great Basin by Oviatt and McCoy and more detailed account from Estancia Valley, New Mexico by Bachhuber certainly help to round out the varied climate and atmospheric changes encountered in North America during this critical Wisconsinan transitional interval.

Is the material presented in Special Paper 270 covered in other volumes? Yes, some of the work presented in these papers

BOOK REVIEWS / 259

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