CENTRE FOR NEWFOUNDLAND STUDIES TOTAL OF 10 PAGES ONLY MAY BE XEROXE (Without Author's Pennission) INFORMATION TO USERS This manuscript has been reproduced from the microfilm master. UMI films the text directly from the original or copy submitted. Thus, some thesis and dissertation copies are in typewriter face, while others may be from any type of computer printer. The quality of this reproduction is dependent upon the quality of the copy submitted. Broken or indistinct print, colored or poor quality illustrations and photographs, print bleedthrough, substan$1ard margins, and improper alignment can adversely affect reproduction. In the unlikely event that the author did not send UMI a complete manuscript and there are missing pages, these will be noted. Also, if unauthorized copyright material had to be removed, a note will indicate the deletion. Oversize materials (e.g., maps, drawings, charts) are reproduced by sectioning the original, beginning at the upper left-hand comer and continuing from left to right in equal sections with small over1aps. Photographs included in the original manuscript have been reproduced xerographically in this copy. Higher quality s· x g• black and white photographic prints are available for any photographs or illustrations appearing in this copy for an additional charge. Contact UMI directly to order. Bell & Howell Information and Leaming 300 North Zeeb Road, Ann Arbor, Ml 48106-1346 USA 800-521-0600 ® National Library Bibliotheque nationale 1+1 of Canada du Canada Acquisitions and Acquisitions et Bibliographic Services services bibliographiques 395 WeUington Street 395, rue Wellington Ottawa ON K1A ON4 OttawaON K1AON4 canada canada Our file Notre rtHtifBitCB The author has granted a non­ L' auteur a accorde une licence non exclusive licence allowing the exclusive permettant a la National Librazy of Canada to Bibliotheque nationale du Canada de reproduce, loan, distnlmte or sell reproduire, preter,. distribuer ou copies of this thesis in microform, vendre des copies de cette these sous paper or electronic formats. Ia forme de microfiche/film, de reproduction sur papier ou sur format electronique. The author retains ownership of the L, auteur conserve la propriete du copyright in this thesis. Neither the droit d, auteur qui protege cette these. thesis nor substantial extracts from it Ni Ia these ni des extraits substantiels may be printed or otherwise de celle-ci ne doivent etre imprimes reproduced without the author's ou autrement reproduits sans son penmss10n. autorisation. 0-612-54960-7 Canada STRATIGRAPHY AND CHRONOLOGY OF DEGLACIAL EVENTS AT HIGHLANDS, SOUTHERN ST. GEORGE'S BAY, SOUTHWEST NEWFOUNDLAND by Kevin Sheppard A thesis submitted to the School of Graduate Studies in partial fulfillment of the requirements for the degree of Master of Science Department of Geography Memorial University ofNewfoundland _April2000 St. John's Newfoundland Abstract This thesis describes and interprets the sedimentology, geomorphology, and chronology of Quaternary deposits at Highlands, southern St. George's Bay, southwest Newfoundland. These deposits are critical in understanding the glacial and deglacial history of the region, and whether retreat was interrupted by a climatic reversal causing a readvance at -12.6 ka BP across the lowlands around St. George's Bay. The physiography of the Highlands area consists of a low-relief coastal plain backed to the east and south by the Long Range and Anguille mountains, respectively. The coastal plain is dominated by gravel near the coast, with till outcropping farther inland The uplands are dominated by bedrock interspersed with till veneer. Late Wisconsinan ice, originating on the southern Long Range Mountains, covered the entire area and extended to a terminal position offshore in St. George' Bay. Striations and clast fabrics indicate that ice flow was generally west-northwestward and unconfined by topography. Deglacial ice flow was affected by topographic highs becoming diverted southwestward down Codroy Valley and south of Bald Mountain. Retreat of ice across the lowlands occurred in a tidewater environment. Sediments exposed in the coastal sections relate to this retreat and were mostly deposited near the grounding-line on a subaqueous fan, as sediment and meltwater entered the sea via a subglacial jet. Two distinct sedimentary sequences relating to the surface topography occur along the coast. The coast is dominated by planar surfaces at 18 to 20 m asl and 24 to 26 m asl, interrupted by the Highlands ridge ranging from 34 m asl at the coast, to >60 m asl inland Exposures through the planar surfaces consist generally of bedrock, overlain successively by diamicton, mud, sand, gravel, and sand and silt. These 11 represent a deglacial sequence from subglacial and pro glacial deposition of the diamicton; to glaciomarine sedimentation of the mud and sand; and glaciofluvial/fluvial deposition of the gravel on outwash terraces. Sand and silt capping the coastal sections are interpreted as aeolian deposits. Exposures through where Highlands ridge intersects the coast (Highlands section) consist of mud, overlain sequentially by sand and gravel; diamicton; gravel and gravelly sand; and sand and silt This section represents the more proximal part of the grounding­ line fan. Diamicton forms a continuous unit along the top of the Highlands section, grading laterally from structureless to stratified, and bas characteristics of subglacial, proglacial, sediment gravity flow, and rainout depositional processes. At one site. a fossiliferous diamicton is interpreted to be deposited by a combination of sediment gravity flows, suspension settling from meltwater plumes and ice rafting, and traction currents. A radiocarbon date of 13 680 ± 90 BP (Beta-120124) on paired shells from this diamicton is interpreted to represent the date of its emplacement. This date lies within the range of all other dates (-13.1 to 14 ka BP) on marine organisms from sediments along the coast of southern St. George's Bay, and suggests that deposition of the diamicton was contemporaneous \vith sedimentation in all areas along the coast. Evidence to support a climatically induced readvance at -12.6 ka BP was not found. iii Acknowledgements Although only my name appears as the author of this thesis, its completion would not have been possible without the support of others that contributed emotionally, academically, and financially. I would first like to thank my supervisor, Dr. Trevor Bell, for his patience, guidance, and encouragement over the last two and a half years. His financial contribution, along with the Department of Geography, School of Graduate Studies, and Graduate Students Union, also provided me with the opportunity to present a paper at the Canadian Quaternary Association's annual conference in Calgary in August 1999. I also greatly acknowledge the receipt of an Atlantic Accord Career Development Award during 1998 and 1999, providing me with additional financial support. I am very grateful to the Government of Newfoundland and Labrador, Department of Mines and Energy (Geological Survey) for offering me employment in their Quaternary mapping programs during the summers of 1996 through 1999. I thank Dr. David Liverman, the other member of my supervisory committee, for his time and effort. He initially introduced me to Quaternary field work in 1996, when I worked as his assistant in Goose Bay, Labrador. I also benefited greatly from working as a senior assistant under his supervision in 1998, when research for this thesis was carried out. Excellent field assistance was provided by Danny O'Dell and Mark Osmond. I thank Dr. Martin Batterson for his encouragement and interesting discussions on the Quaternary geology of the west coast, where I worked as his assistant during this past summer; and for reading various drafts of things I wrote over the last few months. Dave Taylor of the Geological Survey and Andrea Bassan were also very helpful and supportive. Terry Sears, Tony Paltanavange, and Dave Leonard of the Department of Mines and Energy IV cartographic laboratory were always helpful and responsive to my inquiries regarding diagrams and the use of lab facilities; Tony produced the excellent colour surficial maps (Figures 2.1, 2.2). Helen Gillespie of the Department of Earth Sciences (Memorial University) taught me how to use the Sedigraph and was very helpful with the grain size analyses. Completing this thesis was often very frustrating, and without the support of family and friends, would not have been possible. I thank my parents and family who always encourage me to better myself and get the most out of every opportunity. Beverley, my fiance for the last two years has put up with me through good and bad times, making many sacrifices along the way; I also would like to thank her parents for their support v TABLE OF CONTENTS Abstract ................................................................................................................................ ii Acknowledgements ............................................................................................................. i v Table of Contents ................................................................................................................ vi List of Tables ....................................................................................................................... x List of Figures ....................................................................................................................