Johnson begins with an overview of the Australian continent, which is notable for its age, stability, flatness, and aridity. He then gives a primer of basic geology, covering plate tectonics, minerals and rocks, geomorphology, and the orogenic cycle. More geology is explained as relevant in the body of the work, with modern geological features linked to past processes and events.
Five chapters trace the broad history of Australia. The oldest components of Australia, the Yilgarn, Pilbara, and Gawler cratons, came together in the Precambrian; this era also saw the origin of life, banded iron formations, the Ediacaran fauna, stromatolites, and the formation of Gondwana. The "warm times" of the Cambrian, Ordovician, Silurian, and Devonian saw episodes of volcanism and sedimentation extending eastern Australia, with shallow seas at times across the centre; opening with the Cambrian explosion, it was an age of trilobites and fishes.
The Carboniferous and Permian brought extensive glaciation, evidence of which can be found across southern and eastern Australia; peatlands were the precursors to coal basins. The Permian-Triassic mass extinction was followed by warming, with dinosaurs, rainforests and ammonites; there was volcanism in the east, inland seas extended across much of Australia, and separation from India created the West Australian coast. And the past 100 million years brought brown coals and oilshales, flowering plants, mammals, and megafauna extinction; the trend has been cooling with increasing aridity, with separation from Antarctica and movement northwards.
The remaining chapters focus on specific regions or topics "on the edges" of the main continental history. One covers the Eastern highlands, volcanoes, seamounts, and the Great Divide. Another looks at the coastlines and the continental shelf, tsunamis, erosion, and so forth. The Great Barrier Reef gets a chapter to itself. And an unexpected inclusion is a chapter on the solar system, focusing on the moon and meteorites and on Australian impact structures and tektites.
Large-scale geology and evolutionary history are at the centre of all this, but Johnson also zooms in on more local details to illustrate the broader picture. His examples are mostly taken from well known features: the chapter on the Precambrian looks at Uluru, Kata-Tjuta, and Wilpena Pound, for example, while the chapter on coastlines contains a comparison of Sydney Harbour and Port Phillip Bay. Johnson also touches on economic geology and technical advances such as the SHRIMP dating technique. A lot is packed in and it's never the least bit dull or dry.
The Geology of Australia is well illustrated with maps and diagrams — essential for understanding complex geologies and their histories — and a decent but not striking selection of photographs. This is a book every amateur geologist in Australia will want.
Note: there is a second (2009) edition of The Geology of Australia.