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Xerox University Microfilms 300 North Zeeb Road Ann Arbor, Michigan 48106 76-3576 THOMPSON, Woodrow Burr, 1946- THE QUATERNARY GEOLOGY OF THE DANBURY-NEW MILFORD AREA, CONNECTICUT. The Ohio State University, Ph.D., 1975 Geology Xerox University Microfilms , Ann Arbor, Michigan 48106 THE QUATERNARY GEOLOGY OF THE DANBURY-NEW MILFORD AREA, CONNECTICUT DISSERTATION Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University By Woodrow Burr Thompson, B.A., M.S ****** The Ohio State University 19 75 Reading Committee: Approved By Sidney E. White Richard P. Goldthwait Charles E. Corbato iser Department of Geology and Mineralogy Frontispiece. Southward aerial view of Housatonic Gorge (center) and junction of Still River with Housatonic River. Photo by J. A. Pawloski. PREFACE This report is based on field work done by the author during the summers of 19 70 through 19 74. The work was funded by the United States Geological Survey during the first three summers and by the Connecticut State Geological and Natural History Survey during the final summer. It was part of a co-operative mapping program involving the state and federal geological surveys. The geologic maps and much of the other information in the present study will be published by the U.S.G.S. as part of the Geologic Quadrangle Map series. The author gratefully acknowledges the U.S.G.S. for providing base maps and other essential materials for the preparation of this report. Fred Pessl, Jr. and William Langer of the U.S.G.S. visited the author in the field and expressed helpful opinions concerning mapping problems. Robert Melvin of the Water Resources Division of the U.S.G.S. supplied bedrock contour and subsurface data that were important in interpreting the Quaternary stratigraphy of the study area. The writer is especially indebted to Dr. Sidney E. White for his help as faculty adviser and for reviewing this iii manuscript. Editorial comments were also contributed by Dr. Richard P. Goldthwait and Dr. Charles E. Corbato. Dr. White and Dr. Goldthwait visited the study area and ex­ amined the Quaternary deposits that are discussed here. Where possible, the geographic and geologic features mentioned in this report are located with respect to places that are readily identifiable on Plate I. However, it is occasionally necessary to use a grid system to refer the reader to a certain part of the map. The Danbury and New Milford quadrangles (Plate I) are divided into ninths, each of which covers 2.5 minutes of latitude and longitude. These divisions are indicated on Plate I by printed lines on the map border and by crosses that designate their corner pointsc The author has assigned letter symbols to the divisions in the following manner: Danbury quadrangle New Milford quadrangle NW NC NE NW NC NE WC C EC wc C EC SW SC SE sw SC SE Localities that may be hard to find on Plate I are referred to one of the above divisions. This grid system is also used to help locate the sources of samples that are listed in Appendix B. iv All grain-size measurements in this report are in metric units. Metric equivalents are given in parentheses for most other measurements except topographic map elevations. Preference is commonly given to English measurements because of their usage in previous reports — particularly in pub­ lished well and test hole logs. v VITA December 10, 1946 Born - Plymouth, New Hampshire 1968............. B.A. Geology, Dartmouth College, Hanover, New Hampsire 1969-1971....... Teaching Assistant, Department of Geology, The University of Vermont, Burlington, Vermont 1971-1975....... Teaching Associate, Department of Geology and Mineralogy, The Ohio State University, Columbus, Ohio PUBLICATIONS Stone,.B.D., and Thompson, W.B., 19 71, Late Wisconsin . glacial readvance deposits on Isle La Motte, Vermont (abs.): Geol. Soc. America Abstracts with Programs, .v. 3, p. 51. Thompson, W.B., 1971, Rodingite near Thetford Mines, Quebec: Mineralogical Record, v. 2, p. 45-46, 48. Thompson, W.B., 1973, Theories on the origin of pegmatite — a summary: Earth Science, v. 26, p. 77-78. Thompson, W.B., 1974, The Palermo Mine, New Hampshire: Mineralogical Record, v. 5, p. 2 74-279. FIELDS OF STUDY Major Field: Geology Studies in Glacial Geology. Professor Richard P. Goldthwait Studies in Geomorphology. Professor Sidney E, White vi TABLE OP CONTENTS Page PREFACE................................................... iii VITA.................................................... vi LIST OF TABLES......................................... ix LIST OF ILLUSTRATIONS............................. x Chapter I. INTRODUCTION................. 1 Purpose and scope.................. 1 Means of investigation................... 1 II. DESCRIPTION OF THE STUDY AREA .......... 5 Geography.................................. 5 Geomorphology........... 7 Bedrock geology........................... 10 Surficial geology......................... 13 Previous work............................. 16 III. TILL DEPOSITS............................... 19 Introduction.............................. 19 Upper till................................. 19 Lower till.......................... 34 Ages of the upper and lower tills........ 41 IV. GLACIAL-MELTWATER DEPOSITS...........'...... 52 Basis for delineation and correlation of map units............................... 52 Meltwater-stream deposits................ 57 Glacial Lake Danbury deposits............... 6 3 Saugatuck River stage deposits......... 64 Pond Brook stage deposits.............. 68 Pumpkin Hill stage deposits............ 73 Housatonic River stage deposits........ 75 Glacial Lake Kenosia deposits............ 79 Glacial Lake Candlewood deposits......... 80 vii V. LATE-GLACIAL AND POSTGLACIAL DEPOSITS........ 81 Eolian deposits....................... 81 Stream-terrace deposits.................... 84 Flood-plain deposits.................. 85 Swamp deposits............................. 85 Colluvium........................ .......... 87 VI. GLACIAL HISTORY............................... 89 Pre-Wisconsinan events..................... 89 Early Wisconsinan glaciation.............. 91 Late Wisconsinan glaciation............... 92 Recession of the Late Wisconsinan glacier........................ .......... 96 Deposition of stratified drift during deglaciation....... .............. 9 7 VII. LATE-GLACIAL AND POSTGLACIAL HISTORY......... 113 Late-glacial events........................ 113 Postglacial events......................... 118 VIII. SUMMARY........................................ 123 APPENDIX A . LOGS OF WELLS AND TEST HOLES PLOTTED ON PLATE I ....................'................ 127 B. SAMPLE LOCATIONS........... ■.................. 130 C. X-RAY DIFFRACTION DATA FOR CLAY FRACTIONS OF TILL SAMPLES............................ 132 REFERENCES CITED........................................ 135 viii LIST OF TABLES Table Page 1 Grain-Size Analyses of Upper Till Samples....... 25 2 Gasometric Determinations of Calcite and Dolomite Weight Percentages in Till Samples and Till Clasts........... ..................... 33 3 Grain-Size Analyses of Lower Till Samples....... 37 LIST OF ILLUSTRATIONS Frontispiece Page Southward aerial view of Housatonic Gorge and junction of Still River with Housatonic River........................................... i Figure 1 Location of study area........................... 6 2 Outcrop of rottenstone marble between U. S. Route 7 and Grays Bridge Road........... 12 3 Ablation facies of upper till at New Fairfield two-till locality............... 22 4 Grain-size distributions of till samples....... 24 5 X-ray