Morphology and Dynamics of the Rock Glaciers in Southern Victoria Land, Antarctica

Abstract

A baseline study of rock glaciers located in the ice-free valleys of southern Victoria Land, Antarctica, was performed in order to determine their usefulness as proxy tools in studies of climatic change. The distribution of the 32 rock glaciers identified in this analysis is principally attributed to site-specific controls including proximity to localized moisture sources and low ambient site temperature controlled by elevation, orientation, and topographic shading.

The relative activity of rock glaciers and their vertical velocity profiles are inferred from termini morphology. Thirty-eight percent of the rock glaciers are stagnant, 41% show velocity decreasing rapidly with depth, and velocity decreases gradually with depth in the remaining 21%.

A structural-compositional model for 11 rock glaciers, constructed from geophysical data, consists of an ice-free layer from 0.3 to 3 m thick that is underlain by either interstitially frozen debris or ice. Horizontal velocities of 1 to 3 cm yr^-1, surface lowerings ranging up to 1 cm yr¹, and infinitesimal strain rates of 10^-4 yr^-1 were measured for the lower geophysically defined layer of one rock glacier.

Analyses of rock glacier dynamics and internal structure are considered useful in studies of climatic change since (1) the response of the ice-free surface layer and the “core” have the potential for being directly related to site specific thermal regimes and/or the availability of moisture and (2) the responsiveness of these structural units varies from immediate for the surface layer to greater than that of true glaciers for the rock glacier “core.”