Late Tertiary history of the Antarctic ice sheet: Evidence from the Dry Valleys

Data from the Dry Valleys, Antarctica, suggest that outlet glaciers of a local ice cap carved primary valley systems on both flanks of the Transantarctic Mountains, while coeval alpine glaciers eroded exposed intervalley mountain ranges. Subsequently, a thick ice sheet overrode the Transantarctic Mountains at least twice, flowing northeastward across major pre-existing valleys. The youngest overriding episode postdated and the older episode antedated middle to early late Miocene time. We think that an extensive ice sheet covered East and West Antarctica during overriding episodes. The photograph on the cover of the December 1983 issue of Geology</em> (v. 11, no. 12) illustrates the subject of this article.