Late Cenozoic lavas and associated hyaloclastite breccias of the Adare volcanics (Hallett volcanic province) in Robertson Bay, northern Victoria Land rest unconformably on Paleozoic greywackes. Abundant hyaloclastite breccias confined to a paleovalley are consistent with a subglacial eruptive origin. In contrast, the lavas which stratigraphically overlie the hyaloclastite probably were erupted subaerially. K-Ar dating of six lavas and two dikes from this basal sequence all have Late Miocene ages. This further confirms that the oldest Hallett volcanic province rocks are Miocene. Geochemical analyses show the rocks are a typical alkalic petrologic suite similar to ocean island basalt suites.