Late Wisconsinan stratigraphy and chronology at Highlands, southern St. George's Bay, southwest Newfoundland

This paper provides detailed sedimentological and chronological data of coa stal exposures at Highlands in southern St. George's Bay, southwest Newfoun dland. The Highlands section shows a coarsening upward sequence from mud to sand and gravel, and diamicton. and represents an ice-distal to ice-proxim al glaciomarine environment, where sediment was introduced via a subglacial meltwater jet and deposited by underflow, current flow, debris flow, and o verflow on a grounding-line fan. Diamicton forms a continuous unit along th e top of the section, grading laterally from structureless to stratified, a nd has characteristics of subglacial, sediment gravity flow, and rainout de positional processes. At one site, a fossiliferous diamicton is interpreted to be deposited by rainout through a combination of suspension settling fr om meltwater plumes and ice rafting, with subsequent modification by sedime nt gravity flow on the fan slope. A radiocarbon date of 13,680 +/- 90 BP (B eta-120124) on paired shells from this diamicton is interpreted to represen t the date of its emplacement. This date lies within the range of all other dates (similar to 13.1-14 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 with sedimentation in all areas along the co ast. Evidence to support a previously interpreted late-glacial readvance at similar to 12.6 ka BP was not found. (C) 2000 Elsevier Science Ltd and INQ UA. All rights reserved.