Profiles of Late Pleistocene Glaciers in New Zealand

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Abstract
Glaciological theory indicates that, as a first approximation, surface slope of a valley glacier is inversely proportional to depth for a given cross-sectional shape. Data are available on surface slope, depth, cross-sectional shape, and elevation of the floor for the lower parts of the Late Pleistocene (Otiran) glaciers of the Tasman and Godley Valleys, permitting an assessment of the “constant” of proportionality. Applying this theory and apparently reasonable values of the “constant” it has been possible, for Late Pleistocene conditions: (1) to make a rational extrapolation of the longitudinal profiles of the ice surface to the heads of the Tasman and Godley Valleys; (2) to infer longitudinal surface profiles of the ice tongues in and leading from the Wakatipu Valley which agree with the positions and correlations of moraines at their termini; (3) to infer the possible position and elevation of the ice divide in the Haast Pass area and to offer suggestions on earlier erosional history and shifts in the ice divide in this vicinity; (4) to infer the surface configurations of the Franz Josef Glacier; and (5) to estimate the average ice load in a representative strip across the Southern Alps leading, in turn, to an appraisal of postglacial isostatic rebound.