the Victoria Land Basin developed along this rift and were deeply buried, while the Transantarctic Mountains were rapidly uplifted during the last fifty million years and are on the "shoulder" of the rift. The line separating the two is a major crustal suture, with large differences in elevation and crustal thickness across the suture. Many of the volcanoes appear to have formed under the influence of fault zones in the area, and increased activity in the last thirty million years has been correlated to the reactivation of faults. Mount Melbourne is part of a volcano alignment that includes The Pleiades, Mount Overlord, Mount Rittmannall large stratovolcanoeswhich with the Malta Plateau form the Melbourne province of the McMurdo Volcanic Group. In addition, this province consists of numerous smaller volcanic centres, volcanic intrusions and sequences of volcanic rocks, and has been active for the past twenty-five million years. Volcanic edifices buried under sediment are also part of the Melbourne province, including a cone southeast of Cape Washington, which has a size comparable to that of Mount Melbourne. Mount Melbourne and its volcanic field are over a basement of Precambrian to Ordovician age, which consists of volcanic and metamorphic rocks of the Wilson Terrane. The volcano is at the intersection of three geological structures: the Rennick Graben of Cretaceous age, the Victoria Land Basin and the Polar3 magnetic anomaly. The Terror Rift in the Victoria Land Basin runs between Mount Melbourne and Mount Erebus and appears to be related to their existence. Mount Melbourne appears to lie in a graben; the marginal faults on the eastern flank of Mount Melbourne are still active with earthquakes. North–south-trending faulting may also be responsible for the trend in edifice structure, and strike-slip faulting takes place on the eastern flank. Recent offset on faults and Holocene coastal uplift in the area indicates that tectonic activity is ongoing. Tomographic studies have shown an area of low seismic velocity at depth under the volcano, which may be due to temperatures there being hotter than normal. Anomalies underneath Mount Melbourne are connected to similar anomalies under the Terror Rift. These anomalies above depth are focused under Mount Melbourne and the neighbouring Priestley Fault. A low gravity anomaly over Mount Melbourne may reflect either the presence of low-density volcanic rocks or of a magma chamber under the volcano. Composition Trachyandesite and trachyte are the most common rocks on Mount Melbourne, with