at Edmonson Point. It consists of three units of ash-supported, lapilli- and pumice-rich deposits with intercalated breccia lenses that reach a thickness of . They are two ignimbrite units separated by a base surge deposit. Faulting has offset the sequences, which are intruded by dikes. The Edmonson Point ignimbrite was produced by large Plinian eruptions and is about 120,000 years old. The eruption deposited tephra into the Ross Sea, and correlative tephra layers were found in the Talos Dome ice core. After this ignimbrite, a series of dikes gave rise to the Adelie Penguin Rookery lava field. This lava field, which probably formed subglacially, is made up by numerous blocky lava flows with glassy margins that reach a thickness of and are formed by hawaiite and benmoreite. They were fed through numerous dikes, which also gave rise to small scoria cones and spatter cones, and were emplaced non-contemporaneously. A tuff cone rises from the lava field and is formed by monogenetic volcano ejecta, including lava bombs encasing granite fragments and bombs large enough to leave craters in the ash they fell in. Ropy basalt lava flows with an uncertain source vent, and a undissected scoria cone rise above the lava field and complete the Edmonson Point system. The Adelie Penguin Rookery lava field was erupted about 90,000 years ago, and its emplacement may have been accompanied by the emission of tephra recorded in the Talos Dome ice core. Rocks at the summit have ages of between 260,000 and 10,000 years. Individual eruptions have been dated to 10,000 ± 20,000, 80,000 ± 15,000, 260,000 ± 60,000 and 15,000 ± 35,000 years ago. Highly imprecise ages of late Pleistocene to Holocene age have been obtained from the ejecta layer on the summit. One large eruption took place 13,500 ± 4,300 years ago; Last eruption and present-day activity Tephrochronology has yielded an age of 1892 ± 30CE for the last eruption. This eruption deposited a major tephra layer around the volcano, which crops out mainly on its eastern side and in the Aviator and Tinker Glaciers. The three small craters on the rim of the Mount Melbourne summit crater formed at the end of this eruption. No eruptions have been observed during historical time, and the volcano is considered to be quiescent and a low-hazard volcano. Ongoing deformation and seismic activity occurs at Mount Melbourne, and the latter may be caused either by