exposed Ashfield Shale of the Wianamatta group, by the Pacific Highway, Chatswood, Australia

Wianamatta shale is a type of shale prevalent in the Sydney region of New South Wales, Australia. It dates from the Triassic Period. It produces a rich clayey soil, often with poor drainage, such as that in the Cumberland Plain.^[1]

Other rock types found in Sydney include the older Narrabeen shale and the Hawkesbury sandstone.

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