STATE OF MICHIGAN EARLY GLACIAL HISTORY OF THE NORTHWEST PORTION OF BENZIE COUNTY ......................................5 DEPARTMENT OF CONSERVATION Description .....................................................................5 P. J. Hoffmaster, Director Interpretation ..................................................................7 GEOLOGICAL SURVEY DIVISION LATER GLACIAL HISTORY OF CRYSTAL LAKE G. E. Eddy, State Geologist DEPRESSION ...................................................................8 Publication 45 General...........................................................................8 Geological Series 38 Round Lake basin ..........................................................9 Crystal Lake bar region ................................................10 OCCASIONAL PAPERS FOR 1946 ON THE LATER GLACIAL HISTORY OF PLATTE LAKE DEPRESSION .................................................................16 GEOLOGY OF MICHIGAN General.........................................................................16 PREPARED UNDER THE DIRECTION OF Algonquin stage ...........................................................17 R. A. SMITH, State Geologist 1919-1946 Nipissing stage.............................................................19 Post-Nipissing stages...................................................20 INTERRELATION OF WIND DIRECTION AND SHORELINE EXTENSION WITH DUNE DEVELOPMENT..............................................................24 CONCLUSIONS...............................................................25 BIBLIOGRAPHY ..............................................................26 PUBLISHED AS A PART OF THE ANNUAL REPORT OF THE GEOLOGICAL SURVEY DIVISION FOR 1946 ILLUSTRATIONS Copyrighted by Michigan Department of Conservation [Plates] 1947 I. Air Mosaic of Northwestern Benzie County, Michigan..........2 Printed in United States of America Franklin DeKleine Printing Company II. Areal Map Northwestern Benzie County, Michigan. ............5 Lansing, Michigan III. A. View of the outwash plain at Honor ...............................6 PART II B. North side of the Platte River Valley ...................................6 IV. A. Flat surface of delta north of Honor ...............................7 THE GLACIAL AND POST-GLACIAL HISTORY B. Gravel pit in delta west of Honor.........................................7 of the PLATTE AND CRYSTAL LAKE DEPRESSIONS V. A. Delta surface and distributary channel ...........................7 BENZIE COUNTY, MICHIGAN B. Delta remant south side Platte Valley .................................7 VI. A. Airplane view of Point Betsie. ........................................8 JAMES LEWIS CALVER B. Truncated Nipissing dunes Crystal Lake Bar region ...........8 A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy, in the VII. A. Detail truncated Nipissing dune ridge.........................13 University of Michigan. B. Southwest along Algoma Beach.......................................13 VIII. A. Algoma Beach north of Point Betsie Lighthouse .......14 CONTENTS B. Marl layer southwest of Point Betsie Lighthouse ..............14 INTRODUCTION............................................................... 2 IX. A. Truncated Frankfort Moraine.......................................15 Nature of problem and time of field work....................... 2 B. Small parabolic dune southeast of Point Betsie................15 Location and size of area .............................................. 2 X. A. Gravelly deflation zone northwest Point Betsie Methods of study ........................................................... 2 Lighthouse......................................................................15 Acknowledgments ......................................................... 3 B. Detail of deflation zone showing “exploded pebble” Résumé of the lake history within the Michigan Basin .. 3 fragments .......................................................................16 Terminology................................................................... 4 C. Same as B. Fragments of one stone fitted together ........16 Post-glacial uplift ........................................................... 4 XI. A. Morainic Island east of Platte River mouth. .................16 Publication 45, Geological Series 38 -- Part II – Page 1 of 26 B. Active dune area southwest of Platte River mouth............16 INTRODUCTION XII. A. Lower course of Platte River showing meander belt...22 B. Mouth of Platte River.........................................................22 Nature of Problem and Time of Field Work XIII. A. Airplane view of Platte River Point.............................22 Study of the Platte and Crystal Lake depressions, as a B. Dune ridge east of Platte River Point. ...............................23 continuation of the work of Professor I. D. Scott on the origin and arrangement of the sand dunes in the Lake XIV. A. Airplane view across the Platte River Plains .............24 Michigan Basin, was begun under his direction during B. Dune area, south of Aral ...................................................24 the summer of 1937. One month of reconnaissance work was completed in the area in 1937. The field work XV. A. Dune ridge south of Otter Creek, Aral ........................24 was continued throughout the summers of 1938 and B. Fore-dune ridge south of Otter Creek, Aral.......................24 1939, and a short visit of two weeks was made to the XVI. Mouth of Otter Creek, Aral.............................................25 area during the spring of 1939 in order to map the dunes in the Crystal Lake Bar Region. [Figures] Location and Size of Area 1. Map of Round Lake Basin. ..................................................9 The area described in this paper is located in the 2. Suggested development of bar between Round and Crystal northwestern part of the Southern Peninsula of Lakes..............................................................................10 Michigan, between the 44°37' and 44°47' parallels and 3. Crystal Lake Bar Algonquin stage. ....................................11 the 85°56' and 86°16' meridians. It lies within Benzie 4. Crystal Lake Bar Nipissing stage.......................................12 County and includes an area of approximately 85 square miles in the northwestern part of the county. The section 5. Crystal Lake Bar Algoma stage. ........................................14 of the Manistee moraine found within the area forms two 6. Crystal Lake Bar Present stage.........................................15 large depressions, each of which opens to the Lake Michigan Basin. These depressions formed large 7. Western part of the Platte Lake Depression. .....................20 embayments in the shorelines of the high level 8. Platte River Point...............................................................22 Pleistocene Great Lakes. An inclusive study of the former shore lines situated in either depression must 9. Northeastern part of the Platte Lake Depression...............23 include those found in the other, because, during the early part of their history, a connection existed between the two embayments. Eleven lakes are within the area; of these Crystal Lake is by far the largest and covers the entire low part of the Crystal Lake depression. Of the nine lakes located in the Platte Lake depression, Big Platte is the largest. Round Lake, a pond, situated in the low sag in the moraine which separates the two depressions, occupies a portion of the connecting channel that formerly existed across the moraine. The area covered by lakes amounts to approximately 25 square miles, and the remainder of the area of this report is nearly equally divided into cleared or cultivated land and forest. Methods of Study No topographical map has been made of Benzie County, and the county road map was found to be too inaccurate for mapping purposes. The county platbook was very helpful for the general reconnaissance work, but inaccuracies of one-half mile, or even more, were noted in road locations and in the position of lake shores with respect to section lines. During the summer of 1938, a series of sketch maps and compass traverses was made [PLATE I. Air Mosaic of Northwestern Benzie County, for each critical position of the area. After the writer left Michigan.] the field in the fall of 1938, air photographs of a part of Benzie County were made available and these were fitted together to make a mosaic. A photostat copy of this mosaic (plate I) was then utilized as a base map. Publication 45, Geological Series 38 -- Part II – Page 2 of 26 Three instruments were used to determine the Résumé of the Lake History Within the elevations of the abandoned shore lines. An ordinary Michigan Basin hand level was employed for measuring up steep slopes and relatively short distances. During the summer of In any discussion of the post-glacial history of the Platte 1938, a wye-level was utilized in all traverses that and Crystal Lake depressions, it is necessary to refer to involved distances of one-tenth mile or more. This wye- four or five of the lake stages that once existed in the level was not available during the summer of 1939, and Lake Michigan Basin. Inasmuch as the history of the a telescopic stadia level, mounted on a Jacob's staff, Great Lakes is complicated and authoritative agreement was substituted for it. Nearly all traverses were made by is lacking, it seems necessary to define some of these using a light-weight, collapsible