Age of Moraines in Victoria Land, Antarctica

Abstract

Abstract“Fresh-looking” moraines lying within a mile of glaciers in the lowlands of the McMurdo Sound area, Victoria Land, Antarctica have been interpreted by some to be only 50 or 100 yr. old and to have been left by recent glacier retreats. The present author believes that these moraines are considerably older because a comparison of the position of existing glacier fronts in the area with positions on photographs of 50 yr. ago shows no movement of the front or appreciable thickening or thinning of the glaciers during the last 50 yr.Radiocarbon dating of mummified seal carcasses lying near glacier fronts indicates that the glaciers have not been more extensive for at least 1,000 yr. The youngest moraines in the area are ice-cored moraines to the existing glaciers. Radiocarbon dates of algae from extinct ephemeral ponds in the ice-cored moraines indicate the moraines to be at least 6,000 yr. old.Additional evidence for the antiquity of the near-glacier moraines is the presence of a rather uniformly well-developed micro-relief pattern of sand-wedge polygons on both the end moraines and the ground moraines extending up to the existing glacier front. Studies show that it requires hundreds if not thousands of years for such well-developed polygonal patterns to form.