Description: From Meyers and others (2002): "The youngest phase of volcanism on Atka probably began one to two million years ago and was concentrated around the approximate center of the present volcanic field (Fig. 2 [in original text]). Initial volcanic activity consisted of the eruption of a large number of basalt and basaltic andesite flows. These flows vary in thickness from 1 to 2 m and in some places can be traced laterally for up to 2 km in sea cliffs and the walls of glacial valleys. The large basaltic shield produced by this activity is composed almost exclusively of basalts and basaltic andesites with few pyroclastic units. It probably had an original basal diameter of at least 20 km and a minimum subaerial thickness of 100 m at the volcano margin (Myers and others 1986). Subsequent glacial activity produced large valleys cutting this shield which are radially distributed around the center of the island."