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  An easy way to understand 'natural' climate change is to imagine an Ice Age coming every 100,000 years or so. Climate change normally occurs in reasonably regular cycles. This has been the pattern over the last 7-800,000 years. The scientific for Ice Age is Glacial. This name refers to major cold episodes in the Earth's history, when continental ice sheets form, glaciers advance, and sea levels fall. The periods between Ice Ages are called Interglacials. These are times when polar ice caps shrink and glaciers retreat. Their released melt-water then raises sea levels again. We currently reside in one of these warmer phases. The last complete glacial cycle took place between 130,000 and 20,000 years ago. The particular details of this approximately 110,000 year long event have been 'mapped' according to Marine Isotopic Stages (MIS). This involves comparing oxygen isotope ratios preserved in the carbonate shells of long dead marine organisms. Geologists argue that di...

  Comments about the monotony of the mallee are a cultural commonplace. There are, however, a surprising variety of mallee trees, with distinct patterns of distribution across the whole region known simply as "the Mallee". To begin at the beginning, there are two foundational events in our geological past that explain some of this unexpected diversity. The first is a marine incursion into the western part of the Murray-Darling Basin (ca. 6 MYA). Late Miocene and Early Pliocene retreats by the Southern Ocean left its seabed of sedimentary deposits called the Parilla Sand Formation.  The second is a freshwater submergence of much of the same area by the palaeo-Lake Bungunnia (ca. 3.5 MYA). Late Pliocene and Early Pleistocene faults and uplifts blocked the drainage of the Murray and Darling Rivers to the sea. The lake overlaid the Parilla Sand with siltier sediments of Blanchetown Clay and some Bungunnia Limestone, before finally breaching the tectonic barriers and emptying out....

  Australian eucalypts have traditionally been named according to their bark. Smooth-barked species are generally called Gum or Mallee. Rough-barked species are known as Box or Stringybark. There are four smooth-barked eucalypts, three Gum and one Mallee, that typify different parts of the borderlands of Western Victoria. They have become the predominant canopy-trees in areas with particular geographic characteristics. From north to south, these are: (i) Dumosa Mallee , Eucalyptus dumosa , sometimes called White Mallee, is the most widespread of the Mallees. It grows in a great arc across southeastern Australia, from south of Dubbo and Louth in NSW, through northwestern Victoria and the Murray Mallee of SA, to Eyre Peninsula and the Flinders Ranges. Early explorers were not impressed. John Oxley's Journals of Two Expeditions into the Interior of New South Wales  (1820), mentions "those dreadful scrubs of eucalyptus dumosa". Allan Cunningham, his accompanying botanist, is ...