Mount Takahe is a snow-covered shield volcano in Marie Byrd Land, Antarctica, from the Amundsen Sea. It is a mountain with parasitic vents and a caldera up to wide. Most of the volcano is formed by trachytic lava flows, but hyaloclastite is also found. Snow, ice, and glaciers cover most of Mount Takahe. With a volume of , it is a massive volcano; the parts of the edifice that are buried underneath the West Antarctic Ice Sheet are probably even larger. It is part of the West Antarctic Rift System along with eighteen other known volcanoes. The volcano was active in the Quaternary period, from 2.5 million years ago to the present. Radiometric dating has yielded ages of up to 300,000years for its rocks, and it reached its present height about 200,000years ago. Several tephra layers encountered in ice cores at Mount Waesche and Byrd Station have been attributed to Mount Takahe, although some of them were later linked to eruptions of Mount Berlin instead. The tephra layers were formed by explosive or phreatomagmatic eruptions. Major eruptions took place around 17,700years ago—possibly forming an ozone hole over Antarctica—and in the early Holocene. Mount Takahe's last eruption occurred about 7,600 years ago, and there is no present-day activity. Geography and geomorphology Mount Takahe is at the Bakutis Coast, eastern Marie Byrd Land, Antarctica. Bear Peninsula and the Amundsen Sea coast are north of Mount Takahe. It is an isolated mountain, and the closest volcanoes are Mount Murphy and Toney Mountain away. No major air routes or supply roads to Antarctic stations pass close to the volcano, and some parts of the edifice are accessible only by helicopter. The name of the volcano refers to the takahē, a flightless nearly extinct bird from New Zealand; members of the 1957–1958 Marie Byrd Land Traverse party nicknamed an aircraft that had resupplied them "takahe". Mount Takahe was first visited in 1957–1958 and again in 1968, 1984-1985 and 1998-1999. The volcano rises above the ice level to a maximum elevation of . It is an undissected nearly perfect cone, a shield volcano with an exposed volume of about . The subglacial part, which might bottom out at below sea level, could have an even larger volume and is elongated in an east–west direction. On its summit lies a flat, snow-filled caldera with a and volcanic neck. A lava dome may crop out inside the caldera.