An unusual assemblage of geological and geophysical anomalies in Wilkes Land, Antarctica, suggests that these features may owe their origin to hypervelocity impact by an extraterrestrial body. The evidene which supports this conclusion includes a 158.3-mGal negative free air gravity anomaly, apparent structural deformation, basin-shaped profiles in the ice sheet and in the subglacial topography, australite distribution, the probable geologic recency of the features, the presence of rim structures similar to terrestrial, lunar, Martian, and Mercurian impact crater rims, lack of isostatic equilibrium, and the excellent agreement between the morphologic dimensions of observed features and the morphologic dimensions of terrestrial, lunar, Martian, and Mercurian impact craters, namely, crater rim widths, crater rim heights, crater depths, and crater diameters. This evidence reveals a subglacial topography with a depression which is a minimum of 848 m deep and 243 km across. In addition, the 5600 km postulated by other investigators as the distance between the australites and their source impact crater on earth is in excellent agreement with the 4800- to 5800-km distance of the subglacial depression in Wilkes Land from the tektite strewn fields of Australia. Absolute determination of the origin of the feature is dependent upon obtaining more direct evidence, such as shock metamorphic features or fragments of the impacting body, or defining the complete morphology of the subglacial depression.