Geology of the Canberra 1:100 000 Sheet area, New South Wales and Australian Capital Territory

Updated: 2018-04-20

The Canberra 1: 100 000 Geological Sheet covers about 2500 km2 of hilly, upland terrain in the Australian Capital Territory and southeastern New South Wales. The bedrock comprises Ordovician to Silurian sediments and acid volcanics which have been invaded by several generations of Silur<rDevonian acid and basic intrusions. Crustal evolution was from an oceanic environment characterised by turbidites in the Ordovician to a shallow-marine shelf and emerging terrestrial conditions in the Silurian represented by sediments and widespread pyroclastic flows. The sequence has been folded, faulted, and weakly metamorphosed by a series of mid Palaeozoic earth movements which have given a strong meridional trend to the geological structure. The region has been stable since the Carboniferous, apart from minor fault movements and intracratonic sedimentation associated with Cainozoic epeirogenic uplift.