ICE FLOW INDICATORS AND THE BEHAVIOR OF THE HUDSON-CHAMPLAIN LOBE DURING A DRAWDOWN OF GLACIAL LAKE ALBANY

Wright (2014) demonstrated two distinct trends in striation orientation across the northern and central Green Mountains; an older NW-SE regional trend and a localized younger NE-SW trend that ends just north of Killington Mountain. Lowland striations follow the topography and are consistent with thinner, topographically controlled flow. Wright further hypothesizes that this indicates the Hudson-Champlain ice lobe either readvanced/surged or acted as an ice stream. Our data from southern Vermont and the northern Hudson Valley includes limited data for the southern Green Mountains, but generally shows a more N-S trend in the valleys.

Isobases constructed on glacial Lake Vermont shorelines show a distinct E-W trend across the valley suggesting a N-S orientation of the ice sheet profile through the valley. Isobases projected eastward across Vermont to isobases constructed on glacial Lake Hitchcock swing to an NE-SW orientation suggesting more of a NW-SE ice sheet profile in western Vermont and New Hampshire. This is consistent with mapping data that suggests ice margins in the Hudson-Champlain lowlands were farther south than their contemporaneous counterparts in the Connecticut Valley.

The Wright manuscript includes a suggestion that the readvance/surge of the Hudson-Champlain Lobe may correlate to the Luzerne readvance. Yet, recent stratigraphic correlations of the proposed "type" location of the Luzerne readvance with other subsurface and exposure data casts doubt that the Luzerne readvance ever happened. Extensive ice marginal sediment accumulation in a medial moraine setting resulted in the Glen Lake kame moraine NW of Queensbury, NY. This deposition was contemporaneous with Lake Albany. A surge or halt of ice margin retreat in the northern Hudson Valley may have been a consequence of the rapid lowering of Albany lake level that induced faster flow and grounded the ice margin. Evidence for a surge may exist in the kame terrace deposited along the ice margin where this transition occurred.