The Stillwell Hills region comprises granulite facies gneisses which record evidence for multiple periods of deformation and metamorphism spanning more than 2500 Million years. The predominant orthogneiss package (Stillwell Orthogneiss) represents the margin of an Archaean craton exposed in Enderby Land, some 150 km to the west that was reworked during the late Proterozoic. Younger additions to the crust include Palaeoproterozoic charnockitic gneiss (Scoresby Charnockite) and Meso-Neoproterozoic mafic sills and dykes (Point Noble Gneiss, Kemp Dykes) and felsic pegmatites (Cosgrove Pegmatites). Subordinate supracrustal rocks, including metaquartzite, metapelitic, metapsammitic and calc-silicate gneiss (Dovers Paragneiss, Sperring Paragneiss, Stefansson Paragneiss, Keel Layered Paragneiss, Ives Gneiss) are intercalated and interfolded with the Archaean-Palaeoproterozoic orthogneisses.