b'The Australian continent: A geophysical synthesisFeaturePreview of The Australian continent: a geophysical synthesisBrian L.N. Kennett, which measures about 3700 km from north to south and Research School of Earth Sciences, Australian National4000 km from east to west, occupies a significant part of the University, Canberra Australian Plate, which is currently separating from the Indian Brian.Kennett@anu.edu.au Plate in a diffuse zone in the Indian Ocean. Since its separation Richard Chopping, from Antarctica at about 35 Ma, the Australian continent has Research School of Earth Sciences, Australian Nationalbeen moving steadily northwards, currently at around 7 cm/University, Canberra year with respect to a hotspot frame of reference. Australia Richard.Chopping@anu.edu.au is the most rapidly moving continent on the globe, and has swept into the southern fringe of Asia with current collision Richard S. Blewett active in Timor and Papua New Guinea (e.g., van Ufford and Geoscience Australia, Canberra Cloos 2005).Richard.Blewett@ga.gov.auPhysiographic settingThe Australian Continent: A Geophysical Synthesis was launchedAustralia is an island continent with a landmass defined online in August 2018, and in print at the AGCC in October 2018.by a distinctive coastal outline, which has maintained its Since then, the publication has garnered a lot of interest. Lecturescurrent shape for the last 6000 years. At the time of maximum on the material contained within the book are being conductedglaciation, the Australian mainland, Tasmania and the island at ASEG branches around the country throughout 2019. Lecturesof New Guinea formed a single larger and differently shaped have already been given in the ACT, Western Australia andlandmass that stretched from the equator to latitude 45S. Tasmania. Dates will be confirmed for later in the year for lecturesWith the end of the last Ice Age, global temperatures increased, in Queensland, NSW, Victoria and South Australia. much of the continental ice melted and sea levels rose. This caused flooding of the land bridges between Tasmania and the We produced this volume because we wanted to take a freshAustralian mainland 6000 years ago, and between Australia and look at a number of the available Australia-wide datasets, and toNew Guinea 8000 years ago. The rise in sea levels inundated place many disparate datasets together on an even footing. Weabout one-seventh of the larger ice age continent isolating did not aim to provide all of the answers to questions about theTasmania, the Australian mainland and New Guinea.underlying geology of Australia, but to expose readers to theMuch of the present topography of Australia is the result of wide range of datasets available in the hope that together weprolonged erosion by wind and water, since there have been no can begin to unravel Australias complicated geological historymajor mountain building episodes in the last 200 Ma. Dating of and locate its buried resources. the surface regolith indicates a weathering history stretching We are deeply indebted to all of those who assisted inback over 300 Ma in some parts of the continent (Pillans 2008). the provision of information and datasets, and hope thatThe landscape has been strongly shaped by continent-wide the compilation stimulates new thinking about Australiasglaciation; large ice caps developed in the Permian when remarkable geology. Australia was very near the South Pole, and this glacial influence The book is available for free download in PDF form from http:// on the landscape persists to the present day. By the early press.anu.edu.au/publications/australian-continent, and can,Cretaceous, Australia was already so topographically flat, and additionally, be ordered in print form from this location. Toof such low elevation, that a major rise in sea level divided the aid in comparisons, we have produced an electronic imagecontinent into three landmasses as a shallow sea spread over gallery, which is available at http://rses.anu.edu.au/AuSREM/ the land.Continental. This gallery contains all the figures in the book, asToday, the major physiographic features of the Australian well as some additional material. continent comprise: (1) a major Western Plateau with localised The book is published under a Creative Commons Attributionranges incorporating most of the Precambrian cratons, (2) the 4.0 International (CC BY 4.0), www.creativecommons.org/ Eastern Uplands with the highest elevations concentrated licences/by/4.0. We hope that this will encourage people to usealong the Great Divide with dominantly Phanerozoic rocks and the material available in the book, and the auxiliary links. (3) an intervening zone of Interior Lowlands. The topography of the Australian continent is subdued. The highest point on Preview readers are undoubtedly familiar with some of thethe continent, Mount Kosciuszko, is only 2228 m above sea geophysical datasets available. For those who are yet tolevel, and the lowest point is Lake Eyre at 15 m below sea level. download or obtain a copy of the book, we thought we wouldThe average elevation is only 330 m, the lowest of any of the pique your interest by reproducing of the 2nd chapter of thecontinents (Figure 1).book in the following pages. This chapter introduces the settingThe Australian continent currently has passive margins on three of Australia, including its broad tectonic and physical setting,sides and the fourth is the lower plate of a collision zone to and the surface, basement and sedimentary geology of thethe north. Thus, in the recent geological past, there have been continent. no destructive convergent plate margins that are generally associated with mountain building, landscape rejuvenation Continental setting of Australia and the formation of large reliable river systems. The largest rivers thus flow from the Eastern Uplands through the interior Australia, with an area of 7.69 million km2, is the Earths largestlowlands. Many of the rivers, particularly in the north are island and smallest continent. The continental landmass,intermittent, with flow starting in the summer wet season, but 39 PREVIEW APRIL 2019'