It is an elongated mountain with a summit caldera filled with ice with numerous parasitic vents; a volcanic field surrounds the edifice.

[a] Mount Melbourne has mainly erupted trachyandesite and trachyte, which formed within a magma chamber; basaltic rocks are less common.

This type of vegetation is found at other volcanoes of Antarctica and develops when volcanic heat generates meltwater from snow and ice, thus allowing plants to grow in the cold Antarctic environment.

[18] Mount Melbourne is an elongated stratovolcano[19][b] formed by lava flows and tephra fall deposits[c], with gentle slopes.

[40] Small creeks flow down the eastern flank of Mount Melbourne;[6] they are fed by meltwater during summer and quickly disappear when the snow is gone.

[41] The mountain is covered with permanent ice, which extends to the coast[3] and leaves only a few exposures of the underlying rock;[34][42] rocky outcrops are most exposed on the eastern flank.

[32] Glaciers emanating from snowfields on the volcano have deposited moraines;[43] these and tills from both Pleistocene[e] and Holocene[f] glaciations crop out at Edmonson Point.

[45] Tephra layers crop out in ice cliffs[46] and seracs[36] and testify to recent eruptions,[47] including the one that deposited the ejecta and lapilli pumice units on the summit.

[47] They form when snow accumulates on top of tephra that fell onto ice[27] and in the case of Mount Melbourne they indicate eruptions during the last few thousand years.

[60] Perfectly preserved scoria cones occur at Pinckard Table north of the volcanic field, while Harrow Peak is a heavily eroded lava plug.

[61] The total volume of volcanic rocks is about 250 cubic kilometres (60 cu mi)[30] and their emplacement apparently altered the path of the Campbell Glacier.

[56] The volcano is at the intersection of three geological structures: the Rennick Graben of Cretaceous[m] age, the Victoria Land Basin and the Polar 3 magnetic anomaly[n].

[54] Tomographic studies have shown an area of low seismic velocity at 80 kilometres (50 mi) depth under the volcano, which may be due to temperatures there being 300 °C (540 °F) hotter than normal.

[83] 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.

Phenocrysts include aegirine, amphibole, anorthoclase, augite, clinopyroxene, fayalite, hedenbergite, ilmenite, kaersutite, magnetite, olivine, plagioclase and sanidine.

[85][86][87] Gneiss,[56] granulite, harzburgite, lherzolite and tholeiite xenoliths are found in the volcanic field[53] and form the core of many lava bombs.

[35] Inclusions in xenoliths indicate that the gaseous components of the Mount Melbourne volcanic field magmas consist mainly of carbon dioxide.

[7] During the last hundred thousand years the magma chamber became established; this allowed both the differentiation of trachytes and the occurrence of large eruptions.

[94] Hydrothermal alteration has affected parts of the summit area, leaving yellow and white deposits that contrast with the black volcanic rocks.

[100] Volcanic activity migrated north from Cape Washington towards the Transantarctic Mountains and eventually became centralized at Mount Melbourne.

[27] Radiometric dating has shown that the appearance of a landform at Mount Melbourne is not indicative of its age; some well preserved vents are older than heavily eroded ones.

It consists of three units of ash-supported, lapilli- and pumice-rich deposits with intercalated breccia lenses that reach a thickness of 30 metres (98 ft).

[35] The Adelie Penguin Rookery lava field was erupted about 90,000 years ago,[102] and its emplacement may have been accompanied by the emission of tephra recorded in the Talos Dome ice core.

[1] This eruption deposited a major tephra layer around the volcano, which crops out mainly on its eastern side[37] and in the Aviator and Tinker Glaciers.

[65][131] Ongoing deformation and seismic activity occurs at Mount Melbourne,[132][133] and the latter may be caused either by the movement of fluids underground or by fracturing processes.

[141] Geothermal activity occurs around the summit crater, on the upper parts of the volcano[51] and on the northwestern slope between 2,400 and 2,500 metres (7,900 and 8,200 ft) elevation.

[43] Algae,[q][151] lichens,[167] liverworts[r] and mosses[s][3] grow on geothermally heated terrain on the upper parts of Mount Melbourne.

[187] Mount Melbourne was recently active, has a polar night lasting thirteen weeks,[174] has soils containing toxic elements such as mercury,[188] is distant from ecosystems that could be the source of colonization events, and lies away from the westerlies[u], which may explain why the vegetation is species-poor.

[3] The steam freezes in the cold air, forming the ice hummocks that act as a shelter and maintain stable humidity and temperature.

[194] Other species associated with the vegetation are the protozoan Corythion dubium,[195] which is a testate amoeba[142] common in Antarctica[190] and the only invertebrate found in the geothermal habitats of Mount Melbourne,[18] actinobacteria[196] and various actinomycetes[197] and fungal[v] genera.