Architectural variety and solidity are favoured in the buildings of the city by a wealth of beautiful building stones of varied colours (limestones, sandstones, lavas, granites and marbles), in addition to which bricks and Roman tiles are employed.
The former consisting of chalk, as in England, and the latter of sandstones and limestones with Hippurites.
The Mesozoic begins with a Triassic land period in the mainland of Australia; while the islands of the Australasian festoon contain the Triassic marine limestones, which fringe the whole of the Pacific. The Triassic beds are best known in New South Wales, where round Sydney they include a series of sandstones and shales.
The sea encroached far on the land from the Great Australian Bight and there formed the limestones of the Nullarbor Plains.
The Liassic beds are often metamorphosed and the limestones contain garnet and wollastonite.