Title

Late Pleistocene glacial history and magnetic chronostratigraphy, western Adirondack borderland, New York

Date of Award

1991

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Earth Sciences

Advisor(s)

Ernest H. Muller

Keywords

Chronostratigraphy, Western Adirondack borderland, New York State, Glacial history

Subject Categories

Geology

Abstract

New lines of evidence from the western Adirondack borderland have been employed to assess the style of deglaciation and reconstruct the nature and timing of associated proglacial lacustrine and marine (Champlain Sea) events. Contrasting styles of deglaciation, controlled primarily by water depth, resulted in landfast ice withdrawing gradually on the northern slope of the Adirondacks while actively calving ice, retreating rapidly in the deep water of Lake Iroquois, quickly evacuated the western St. Lawrence Lowland of ice. The extent of ice retreat from the western St. Lawrence Lowland during the life of Lake Iroquois has been estimated on the basis of the distribution of the ostracode Candona subtriangulata in Lake Iroquois and by northward projections of Iroquois shoreline elevations to the region bounded by the Madawaska Highlands (Ontario). Results indicate that models envisioning calving-bay recession in the Ottawa Valley contemporaneous with proglacial lakes in the St. Lawrence Lowland are improbable.

Study of the forms and possible origins of glacial erosional and depositional features in the Adirondack borderland highlights the importance of the presence of an impermeable substrate and the role of meltwater in the lowlands as channelized subglacial flows. Deep sheetfloods are not required to account for the erosional features described from the western St. Lawrence Lowland. Instead, plastic deformation of the glacier sole in near conformity with pre-existing subglacial topography accounts for characteristics of erosional forms produced both by meltwater and by glacial erosion.

Secular changes in the depositional remanent magnetism (DRM) are used as a means of testing time equivalence between glaciolacustrine/marine facies associated with ice marginal positions. Construction of a glacial-magnetic record suggests possible correlations of events in the western Adirondack borderland of New York with evolving glacial-magnetic records from the Champlain Valley and New England independent of morphostratigraphic inferences.

The shape and amplitude of the secular variation curve preserved by the glaciolacustrine and marine sediments from the western Adirondack borderland show strong agreement between secular variation records from both other varve-based records and high resolution wet sediment cores. These results clearly demonstrate the potential of these records for correlation and show that comparison of geographically distinct sites is possible with a resolution unparalleled by radiocarbon dating.

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