University of Vermont ScholarWorks @ UVM Graduate College Dissertations and Theses Dissertations and Theses 2018 From Sea To Lake: The epD ositional History Of Saint Albans Bay, Vt, Usa Matthew Kraft University of Vermont Follow this and additional works at: https://scholarworks.uvm.edu/graddis Part of the Geology Commons, and the Other Ecology and Evolutionary Biology Commons Recommended Citation Kraft, Matthew, "From Sea To Lake: The eD positional History Of Saint Albans Bay, Vt, Usa" (2018). Graduate College Dissertations and Theses. 857. https://scholarworks.uvm.edu/graddis/857 This Thesis is brought to you for free and open access by the Dissertations and Theses at ScholarWorks @ UVM. It has been accepted for inclusion in Graduate College Dissertations and Theses by an authorized administrator of ScholarWorks @ UVM. For more information, please contact [email protected]. FROM SEA TO LAKE: THE DEPOSITIONAL HISTORY OF SAINT ALBANS BAY, VT, USA A Thesis Presented by Matthew P Kraft to The Faculty of the Graduate College of The University of Vermont In Partial Fulfillment of the Requirements for the Degree of Master of Science Specializing in Geology May, 2018 Defense Date: January 23rd, 2018 Thesis Examination Committee: Andrea Lini, Ph.D., Advisor Shelly Rayback, Ph.D., Chairperson Char Mehrtens, Ph.D. Cynthia J. Forehand, Ph.D., Dean of the Graduate College ABSTRACT Sediment accumulated in lakes stores valuable information about past environments and paleoclimatological conditions. Cores previously obtained from Saint Albans Bay, located in the Northeast Arm of Lake Champlain, VT record the transition from the Champlain Sea to Lake Champlain. Belrose (2015) documented the presence of a peat horizon separating the sediments of the Champlain Sea from those of Lake Champlain. Initially, this layer was thought to comprise the transition from the marine environment of the Champlain Sea to a freshwater wetland. However, based on the results from this study, the transition between marine and freshwater conditions is thought to be represented by an erosional unconformity, indicative of a lowstand at the end of the Champlain Sea period. For this study, five additional cores were collected from Saint Albans Bay along a transect following the long axis of the bay moving into progressively deeper water. These cores better constrain the spatial extent, thickness and age variability of the peat layer within the bay and allow us to better understand the environmental conditions that preceded the period of peat deposition. In each of the cores there is evidence of sediment reworking in the uppermost Champlain Sea sediments, indicated by the presence of coarse-grained sediment, which is suggestive of a lowstand at the end of the Champlain Sea period before the inception of Lake Champlain. This coarse-grained layer is immediately overlain by a thick peat horizon. The widespread occurrence of the peat layer points to a large wetland that occupied the entire inner portion of Saint Albans Bay, and lake level ~ 9 m lower than at present during the Early Holocene. Based on radiocarbon dating, this paleo-wetland existed in Saint Albans Bay from ~ 9,600-8,400 yr BP. The development of this wetland complex is time transgressive, reflecting rapidly increasing lake level during the Early Holocene. This hypothesis is supported by the basal peat radiocarbon dates, as well as by the composition of plant macrofossils recovered from the peat horizons. The shift from peat deposition to fine- grained, low organic content lacustrine sedimentation is believed to have occurred at ~8.6- 8.4 ka and is likely the result of continued isostatically driven lake level rise coupled with a changing climate. Although it was not its primary focus, this study also seeks to address the variations in sediment composition in the Lake Champlain sections of the cores. Evidence from the Lake Champlain record in Saint Albans Bay indicates that there were notable fluctuations in sedimentation, which were likely linked to both climatic variations and a change in the morphology of the bay. The rebound in productivity from ~8-5 ka is likely the result of warmer conditions during the Hypsithermal period. An increase in terrigenous sedimentation during this same time suggests a change in the morphology of the bay in which the Mill River delta migrated towards the inner bay. Initially, the cooler conditions of the Neoglacial are reflected in Saint Albans Bay by a decrease in organic matter content from ~5-3 ka. During the latter part of the Neoglacial (~3-1 ka), increases in organic matter content and detrital input point to enhanced productivity in response to increased precipitation and runoff from the watershed. The most recently deposited sediments in Saint Albans Bay bear out the legacy of anthropogenic nutrient enrichment of the bay in the form of increased algal productivity. ACKNOWLEDGEMENTS For starters, I would like to say how grateful I am for the opportunity to pursue graduate studies at the University of Vermont. I first came to Vermont in 2013 to work as a research technician at Middlebury College and fell in love with this beautiful state and built lasting relationships with people and places here. To come back and pursue my studies further at UVM is an opportunity that I never imagined possible, and I have gained wonderful memories that I will cherish for the rest of my life. There are too many people in my life that have assisted me in getting to this point in my career, so I will only name a few. First, I would like to thank my advisor Andrea Lini. You have always been a great mentor and I would not have been able to complete this thesis without your endless assistance and the vast knowledge that you have bestowed upon me. Next, I would like to thank my family for always believing in me and pushing me to always do my best, even when I was feeling discouraged, you were always there to pick me up and offer encouragement. There are many people in the geology department that have provided me assistance during my time here that I would like to thank. I would like to thank Stephen Wright for sharing his vast knowledge of Vermont’s geology with me, as well as the great times I shared with him while teaching introductory and environmental geology. I would also like to thank John Hughes, Paul Bierman, and the rest of my committee for helping me develop my writing and providing input on my thesis. I would also like to thank Jake Zandoni and Taylor Norton for the assistance with core collection and lab work. ii Finally, I would like to thank Kellie Merrell and Leslie Matthews from the Vermont Department of Environmental Conservation, Lakes and Ponds Management and Protection Program. The experience that I gained working with you has been invaluable in completing my thesis. The days of hiking canoes into remote lakes and slogging through beds of aquatic plants with you are some of my fondest memories and remind me every day why I became I scientist. iii TABLE OF CONTENTS Page ABSTRACT ........................................................................................................................ I ACKNOWLEDGEMENTS ............................................................................................ II LIST OF FIGURES ........................................................................................................ VI LIST OF TABLES .......................................................................................................... XI CHAPTER 1 : INTRODUCTION ................................................................................... 1 CHAPTER 2 : LITERATURE REVIEW....................................................................... 4 2.1 GEOLOGIC SETTING OF THE CHAMPLAIN VALLEY ..................................................... 4 2.2 POST-GLACIAL HISTORY OF THE CHAMPLAIN VALLEY .............................................. 5 2.2.1 Lake Vermont .................................................................................................... 5 2.2.2 Champlain Sea ................................................................................................... 7 2.2.3 Champlain Sea – Lake Champlain Transition ................................................... 9 2.2.4 Tilted Water Planes in the Champlain Valley & Lake Level .......................... 15 2.3 LACUSTRINE SEDIMENT AS AN ARCHIVE OF ENVIRONMENTAL CHANGE ................. 21 2.3.1 Biological Indicators (%C, %N, & C/N) ......................................................... 22 2.3.2 Carbon Stable Isotopes .................................................................................... 26 2.3.3 X-ray Fluorescence Bulk Geochemistry .......................................................... 29 2.3.4 Grain Size Analysis .......................................................................................... 31 2.3.5 Peat Micro & Macrofossils .............................................................................. 32 2.4 LIMNOLOGY OF LAKE CHAMPLAIN .......................................................................... 37 2.4.1 Saint Albans Bay Watershed & Limnology ..................................................... 40 2.4.2 Bedrock & Surficial Geology of Saint Albans Bay ......................................... 44 2.5 PREVIOUS PALEOLIMNOLOGICAL INVESTIGATIONS OF SAINT ALBANS BAY ............ 46 2.6 REGIONAL PALEOCLIMATE STUDIES ........................................................................ 57 CHAPTER 3 : METHODS ...........................................................................................