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Bulletin of the Geological Society of America Vol. 67

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Bulletin of the Geological Society of America Vol. 67 BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA VOL. 67. 271-288. 6 FIGS.. 1 PL. MARCH 1966 LATE WISCONSIN CHRONOLOGY OF THE LAKE MICHIGAN BASIN CORRELATED WITH POLLEN STUDIES BY JAMES H. ZUMBERGE AND JOHN E. POTZER* ABSTRACT Geological interpretation and radio carbon dating of an excellent exposure in a wave- cut cliff on the shore of Lake Michigan near South Haven, Michigan, permits the es- tablishment of the following absolute chronology of events for the Lake Michigan Basin: Two Creeks-Bowmanville low-water stage, 11,000 years ago; end of Lake Algon- quin, 8000 years ago; Lake Chippewa low-water stage, 5000 years ago; and beginning of the Nipissing Great Lakes, a little less than 4000 years ago. Pollen profiles from the South Haven section and from a bog near Hartford, Michigan, on the Valparaiso ground moraine reveal the following forest succession in southwestern Michigan from Two Creeks time to the present: spruce-fir to Jack pine to white-red pine to oak to oak-hemlock-broad-leaved forest to oak-pine. Radiocarbon dating indi- cates that the close of the spruce-fir period was 8000 years ago; the Jack pine period, 7000 years ago; the white-red pine period, 6000 years ago; the oak-pine period, 5000 years ago; and the oak-hemlock-broad-leaved forest (Xerothermic), 4000 to 3500 years ago. The difference in time between Lake Algonquin and the Nipissing Great Lakes was 4000 years. The Xerothermic is correlated with the Nipissing Great Lakes at 4000-3500 years ago. CONTENTS TEXT Page p Summary of pollen studies at South Haven . , .. 2% and Hartford bog 286 IntroductioT n 272 f e cited 287 Acknowledgments 272 Re erenc S Resume" of the Late Wisconsin history of the ILLUSTRATIONS Lake Michigan basin 272 Figure Page Previous work 272 L Index map 274 Glacial Lake Chicago 272 2 Wave-cut cliff exposure along Lake Michigan Lake Algonquin. 273 shore near South Haven, Michigan 275 at r 01 111 sta es J; ? . Ate "! ? . g 273 3- Chart showing geologic section and radio- Nipissmg Great Lakes 273 carbon dates from the South Haven Algoma Great Lakes 273 s;te 276 Low-water stages in the Lake Michigan 4. Correlation "chart'of'geologic'events'with basin.. c,'-;,'^ T;;-1;.-"" %* forest succession 277 Geologic section near South Haven, Michigan .274 s Pollen diagram of the South Haven section.. 278 Description 274 diagram of the Hartford bog 282 Geologic interpretation 277 6 Pol]en Summary of geologic events as indicated by Plate Facing page the South Haven section 279 j. Views of the South Haven section 274 Radiocarbon chronology 280 Previous work 280 TABLES Discussion of South Haven radiocarbon Table Page dates 280 l. Comparison of Antevs, Flint, and Zumberge- Pollen studies of the South Haven and Hartford Potzger chronologies 283 sites 281 2. Pollens of shrubs, trees, and herbaceous Introduction 281 plants, and spores of ferns counted at Methods of collecting and preparing samples South Haven 284 for pollen analysis 281 3. Pollens of shrubs, trees, and herbaceous Pollen profiles 283 plants, and spores of ferns, Hartford Discussion 283 bog 285 —— 4. Climatic change inferred from forest history * Deceased, September 18, 1955 in southwestern Michigan 286 271 Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/67/3/271/3416636/i0016-7606-67-3-271.pdf by guest on 02 October 2021 272 ZUMBERGE AND POTZGER—LAKE MICHIGAN BASIN INTRODUCTION Harbor, Michigan, deserves credit for the initial discovery of the South Haven exposures. For more than 50 years geologists have been Finally, the authors wish to express their studying the late Pleistocene history of the sincere appreciation to the following who pro- Lake Michigan basin. From this mass of infor- vided the C14 dates appearing in this paper: mation a detailed sequence has been deciphered, Richard Crane, University of Michigan Phoe- ranging from the earliest impounding of glacial nix Project Radiocarbon Laboratory; W. F. water (Lake Chicago) to modern Lake Michi- Libby, University of Chicago Radiocarbon gan. Fluctuations of the ice front, shifts in Laboratory; Hans Suess and Meyer Rubin, U. outlets, and differential uplift of the land have S. Geological Survey Radiocarbon Laboratory, contributed to the changes in elevation of the and Wallace Broecker and J. Laurence Kulp, water plane during the final wastage and dis- Columbia University Lamont Geological Ob- appearance of the last Wisconsin ice sheet. servatory. One of the more striking later contributions to this history has been discovery of extreme low-water stages. Prior to the recognition of RESUME or THE LATE WISCONSIN HISTORY OF these stages in lake history, geologists assumed THE LAKE MICHIGAN BASIN that modern Lake Michigan attained its pres- ent level through a series of consecutive steplike Previous Work lowerings (owing to various causes). The framework of the present concept of late This paper presents further evidence in sup- Wisconsin history of the Lake Michigan basin port of these low-water stages of the Lake had its inception with the report of T. C. Michigan basin and integrates the generally Chamberlin in 1877. Since then, additional accepted chronology into an absolute time scale findings by other workers have added much to based on radiocarbon age determinations. A the sequence of events. (See Taylor, 1894; further aim is to correlate climatic changes as Leverett, 1899; Alden, 1902; 1906; 1918; J. W. indicated by forest succession in southwestern Goldthwait, 1906; 1907; 1908; Leverett and Michigan during late Wisconsin time. Pollen Taylor, 1915; Wright, 1918.) More recent con- studies by J. E. Potzger have been employed tributions by Stanley (1938), Bretz (1951), and as the basis for this correlation. J. H. Zum- Hough (1952; 1953; 1955) are especially impor- berge made the geological investigations and tant in that they supply evidence bearing on interpretations. low-water stages below the present level of Lake Michigan. ACKNOWLEDGMENTS During the field investigations, geologists, Glacial Lake Chicago palynologists, and ecologists visited the expo- sures near South Haven. Among these were J The proglacial lake that formed at the south- Harlen Bretz, the late Leland Horberg, Bjorn ern margin of the retreating Lake Michigan lobe Andersen, Pierre Dansereau, and Stanley A. was named Glacial Lake Chicago by Leverett Cain. Their discussions at the site and exami- (1897, p. 65). Three stages of this lake are re- nation of results is greatly appreciated. J Har- corded by shore features above the modern len Bretz and the late Leland Horberg read the lake: the Glenwood stage, 60 feet above the manuscript and gave the writers valuable present lake; the Calumet, 40 feet above criticism. modern lake level; and the Toleston at 20 feet Appreciation is also expressed to Charles above the modern water plane. The reasons for Shinn and William Grable of Larchmoor for the changes in level were discussed by Bretz their co-operation in providing access to the site (1951) and need not be considered here. itself, and to the Michigan Congregational The term "Calumet stage" as used in this Christian Conference for hospitality extended paper is the same as Bretz's "second attained and for permission to work on the Pilgrim Calumet level" (Bretz, 1951, p. 427) and Calu- Haven property. Mr. Harvey Franz of Benton met II as used by Hough (1953, p. 99). Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/67/3/271/3416636/i0016-7606-67-3-271.pdf by guest on 02 October 2021 RESUME OF LATE WISCONSIN HISTORY OF LAKE MICHIGAN BASIN 273 Lake Algonquin Nipissing Great Lakes Lake Algonquin was the first body of water The Nipissing Great Lakes occupied the area to occupy the entire Lake Michigan basin. The now covered by Lakes Superior, Michigan, and position of the ice border at the time of the in- Huron. Most of the earlier students of Lake ception of the Algonquin stage is not known, Nipissing considered its level to have been about but Hough (1953, p. 101) believes that it was 15 feet above modern Lake Michigan (Alden, somewhere in the Northern Peninsula of Michi- 1918, p. 337; Leverett and Taylor, 1915, p. 449; gan and that much of the eastern end of Lake Tague, 1946, p. 17) or about 595 feet A.T. in Superior was ice-blocked at that time. This the southern Lake Michigan basin, but Hough would not permit Lake Algonquin to communi- (1953, p. 89-90) concluded that the Nipissing cate with any part of the Lake Superior basin and Algonquin water planes were both at 605 as supposed by Leverett (1929, p. 65) and feet A.T. before upwarping. This difference in Sharp (1953, p. 120). In either interpretation interpretation is not critical to this study al- Lake Algonquin ("highest Algonquin" of though the writers prefer Hough's reconstruc- Stanley, 1936, p. 1954) used the St. Clair- tion of the Algonquin-Nipissing history. Detroit River and the Des Plaines River out- lets. The reconciliation of these two ideas is not Algoma Great Lakes critical to this study. Lake Algonquin in the Lake Michigan basin was at about the same Younger beaches 10-15 feet above the pres- elevation as Lake Toleston (605 feet A.T.). The ent level of Lakes Michigan and Huron were exact relationship of the Toleston stage of Lake ascribed to the Algoma stage of lake history by Chicago to Lake Algonquin is not completely Leverett and Taylor (1915, p. 449). Tague resolved, although Hough (1953), p. 37) con- (1946, p. 18) followed Leverett and Taylor's sidered that the Toleston stage ended when the interpretation, but Hough's interpretation Valders ice retreated sufficiently far north to (1953, p. 92) required all beaches referred to the open the Traverse Bay lowland or the Strait of Nipissing Great Lakes by his predecessors to be of Algoma age.
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