THE NEW YORK CROSS-STATE CHANNELS: EVIDENCE FOR COMPLEX AND LARGE SCALE LATE WISCONSIN MELTWATER DRAINAGE EVENTS

In up-state New York between Buffalo and Rome, exist a complex network of large channel forms oriented E-W across portions of the Erie-Ontario Lowland and the northern edge of the Onondaga Escarpment. Originally recognized by Fairchild (1909) these channels have been attributed to Late Wisconsin ice marginal drainage associated with the Ontario Lobe of the Laurentide Ice Sheet. Recently developed high resolution DEMs reveal details that shed new light on these drainage features. Despite their unambiguous appearance, many of these meltwater features have only received limited amount of investigation. Morphologically the channels range in size from .25 km – 1km in width, 10-30 meters deep and continue as anastamozing and single channels for 10's of kilometers. Channel forms crosscut drumlin fields, former ice marginal positions and appear to have been coincident with many large proglacial lakes in central New York. Channel incision occurs in both unconsolidated glacial deposits and Paleozoic sedimentary rocks. Some channel segments appear to be polygenetic in origin and may have been used multiple times to route drainage from earlier glacial cycles or recurrent ponding associated with ice-marginal fluctuations. Most channels likely formed as a result of incision from conventional meltwater processes, although some localities display stratigraphic, sedimentologic and geomorphic evidence suggestive of catastrophic discharges. Coarse cobble-delta deposits on the western flank of N-S trending valleys in western and central NY record the influx of sediment charged floodwaters into proglacial lakes and deeply incised spillways on the eastern flanks are suggestive that some discharges may have overwhelmed these basins and delivered meltwater eastward. The cross-state channel complex eventually directed meltwater into the ancestral Mohawk and down the lower Hudson River Valley. The source of meltwater may have been associated with elevated proglacial lake levels within the Eire basin or simply short duration, high magnitude discharges from localized proglacial basins.