ABSTRACTAn40Ar/39Ar chronology ofin-situto nearin-situvolcanic ashfall deposits indicates that the surficial stratigraphy of Arena Valley extends back at least to middle-Miocene time. Wet-based glacial ice occupied part of Arena Valley more than 11.3 Ma ago. Thick, northeast-flowing ice subsequently engulfed Arena Valley, again more than 11.3 Ma ago. Only minor glacier expansion occurred during Pliocene and Pleistocene time. The maximum Pliocene thickening of Taylor Dome, 35 km inland of Arena Valley, was certainly less than 475 m and probably less than 250 m. Maximum thickening of Taylor Dome was less than 160 m during the Pleistocene.The preservation of Miocene-and Pliocene-age ashes on steep valley slopes indicates that the major bedrock land-forms of Arena Valley are relict and that little slope evolution/colluviation has occurred during the last 11.3 Ma. The geologic record of Arena Valley glaciation and landscape evolution shows persistent cold-desert conditions and hence implies stability of the adjacent East Antarctic Ice Sheet for at least the last 11.3 Ma.