page_title: Great Western Woodlands
section_title: Geological history
hierarchical_section_title: Great Western Woodlands / History / Geological history
caption_attribution_description: English: Banded Ironstone Formation (BIF) ranges of Helena Aurora Range- Sara Marques
context_page_description: The Great Western Woodlands is the largest and healthiest temperate woodland remaining on Earth. Located in the southwest of Australia, the woodlands cover almost 16,000,000 hectares, a region larger in size than England and Wales. The boundary of the Great Western Woodlands runs from the Nullarbor Plain in the east to the Western Australian Wheatbelt in the west; from north of Esperance through to the inland mulga country and deserts that are found north of Kalgoorlie.
  The boundaries of this region were established by researchers from the Australian National University working with The Wilderness Society and are based on satellite data of the region's natural ecosystems and vegetation types. The vegetation in this region is botanically diverse, and ranges from mature eucalypt woodlands dominating the landscape, interspersed with large areas of mallee, shrublands and grasslands.
  The Great Western Woodlands region is part of one of the world's "global biodiversity hotspots", the South West Western Australia Floristic Province, with new species of flora and fauna still being discovered.
context_section_description: The majority of the Great Western Woodlands sits atop the stable geological formation known as the Yilgarn Craton that was formed between 2,400 and 3,700 million years ago. This formation contains some of the oldest mineral deposits ever recorded on the Earth's surface. The region also has a series of geological intrusions running parallel to the Earth's surface, known as the greenstone belts. These formations house large quantities of gold and nickel, and also provide very rich and mineralised soils, which have led in part to the evolution of locally distinctive flora.
  A major geological event in the history of the Great Western Woodlands was a period of glaciation that occurred between 250 and 330 million years ago. During this time, a massive ice-sheet covered most of Australia, flattening much of the landscape. The Great Western Woodlands region has remained undisturbed by glaciation since that time, and the remaining granite outcrops are now significant landmarks.
  Salt lakes are found throughout the Great Western Woodlands. These are remnants of ancient drainage systems (such as rivers) from about 65 million years ago, and are valuable habitats supporting a variety of vertebrates and invertebrates.
caption: Banded Iron Formation of the Yilgarn Craton
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