The geology of Melbourne was formed over hundreds of millions of years. Some interesting points of note are:
- The Murray Darling Basin used to be an inland sea
- The southern coast of Australia is rising slowly, which has lifted much of it above sea level
- Melbourne’s “sand belt suburbs” are built on remnant sand dunes that were formed when they were an ancient sea shore – when seas were higher. Similar remnant dunes are found in the Murray Darling Basin well inland
- Melbourne’s geology is based on Silurian sedimentary rock which was laid down in a marine environment about 400 million years ago
- Basalt lava flows from active volcanoes travelled to the sea and dammed the Plenty and Yarra Rivers and Banyule and other creeks. These dams formed what is now the river flats of these rivers.
- The rivers eventually broke free of their dams to form their present day courses.
- Terrestrial sediments formed a sandy layer during the Pliocene. These have been eroded from most of Melbourne, but remain in high areas such as Mont Albert and Surrey Hills, where there is 1 to 2 metres of sandy soil above a clay layer.
- Geology of Melbourne Presentation, Professor Andrew JW Gleadow