 Hobart is located on the estuary of the River Derwent in the state's south-east.Geologically Hobart is built predominantly on Jurassic dolerite around the foothills interspersed with smaller areas of Triassic siltstone and Permian mudstone.Hobart extends along both sides of the River Derwent; on the western shore from the Derwent valley in the north through the flatter areas of Glenorchy which rests on older Triassic sediment and into the hilly areas of New Town, Lenah Valley.