Mount Andrus is the youngest of the shield volcanoes in the Ames Range, which formed during the Miocene.
Late-stage volcanic activity resumed at Mount Andrus in the late Pleistocene or the Holocene.[3]
Its has a 4.5 kilometres (2.8 mi) wide caldera at its summit.
While the age of Mt. Andrus is not well known it is one of the oldest trachytic shield volcanoes in Marie Byrd Land, similar in age to Mount Hampton.
The westward face of the mountain is drained by the Coleman Glacier, with significant crevassing present. [4]
Le Masurier, W. E.; Thomson, J.W., eds. (1990), "B. 12. Ames Range", Volcanoes of the Antarctic Plate and Southern Oceans, Antarctic Research Series vol 48, Washington, DC: American Geophysical Union, pp. 216–220, doi:10.1029/AR048, ISBN9781118664728