The Australian Environment before Human Habitation Mat Hyland Notre Dame College Introduction 4.6 billion years ago the earth was formed Humans (Aboriginals) arrived in Australia approx. 46 000 years ago. Europeans arrived 212 years ago (1788) The 24 hour clock! Imagine that time on earth fits into one whole day (A 24 hour clock). Seeds 4.15 billion years to 3.5 billion years (0220hrs - 0544hrs) At 2.00am on the clock the planet is still in the process of birth. The seeds are being sown. Meteorites bombard it incessantly, and heat from these impacts, and from atomic decay in the planets pressurised core, fuses it into a ball of iron-rich magma. Rocks as old a 4.16 billion years ago have been found at Mt Narryer in Western Australia. Signature 3.5 billion years to 2.5 billion years (0544hrs - 1057hrs) At 6.00am on the clock our solar system was born and planets start to orbit the sun. Carbon atoms link to other atoms of which some can replicate. It is this chemistry that leaves a faint signature on future life. Breath of Life 2.5 billion years to 1.8 billion years (1057hrs - 1435hrs) At 11.00am the world is warm and cloudy and its surface is largely covered by shallow seas. Each day (one revolution) lasts only 18 hours. Australia at this stage consists of two major landmasses lying relatively close to each other somewhere near the north pole. Bacteria have proliferated to trigger major environmental change. Invaders 450 million years to 350 years (2139hrs - 2210yrs) Land is still barren Some algae have adapted to occasional exposure to air (O2). With the aid of root cells and vascular stems these algae colonise the shoreline. Miniature forests entice animals to follow. The first of these are millipedelike vegetarians equipped with legs and water tight skin. However they are short lived. Spur of Adversity 330 million years to 200 million years (2127hrs - 2257hrs) Pangaea is formed. (All the earths land massess accumulate on one side of the earth distupting global weather patterns). At 10.20pm climates become erratic and a new ice age is born. Crustal drift carries Gondwana (the southern half of Pangaea) from one side of the pole to the other. Migration of polar ice carves is way across five continents. Almost all life forms are extinguished. However many new species appear. Two survival techniques to emerge are the “seed” and the “egg”. Stirring the Stew 200 million years to 130 million years (2257hrs - 2319hrs) At 11.00pm most of the surface is already inhabited by a multitude of forms that are complex and well adapted to their environments. The day is slightly shorter than ours, the climate is warmer and there is little or no snow, even at the poles. Ancient conifers now dominate hill sides. Ferns and tree ferns clothe the valleys. Some amphibians remain and with the evolution of the reptile egg, the first dinosaurs emerge. An Omen 130 million years to 65 million years (2319hrs - 2340hrs) At 11.20pm a comet bursts out of the southern skies and plunges to earth in the very centre of Australia. Flooding is widespread cause of high sea levels. Life is thriving. Conifer, cyad and tree fern forests cover Australian & Antarctica supporting a large dinosaur population. The evolution of the flower begins. Last Exit 65 million years to 53 million years (2340hrs - 2344hrs) In the last twenty minutes of our time scale, temperatures take their first serious plunge since the previous ice age. Vegetation everywhere undergoes massive change and a series of extinctions begins to sweep through the animal kingdom. This includes the disappearance of the dinosaurs. Anatarctica begins to separate from Australia after a billion years. Great Southern Ark 53 million years to 20 million years (2344hrs - 2354hrs) Birds and Mammals now dominate as Australia recovers from one of the worst series of extinctions in its history. As the temperatures continue to descend another ice age exists. Australia drifts north towards the tropics. Plants and animals are forced to look at defence mechanisms. They must adjust to a new climate and a shift in Latitude of 250 Gathering Storm 20 million years to 5 million years (2354hrs - 2358hrs) Australia northern edge ploughs into the Pacific Ocean Plate, pushing up a series of islands known as New Guinea Highlands. With about four and a half minutes to go, polar temperatures take another plunge. Grasslands spread throughout temperate regions and large grazing animals poliferate. Among these are the ancestors of modern kangaroos and wallabies. Fire & Ice 5 million years (2358hrs) With 90 secs to go the climate is much like it is today. Giant mammals thrive all over the world, however in Australia this is limited due to lack of water. Large birds survive well. Huge flocks of pelicans, flamingoes, swans, ducks and other large water birds all congregate around the shrinking remnants of ancient inland lakes. With 30 secs to go, world temperatures take a final plunge into yet another ice age. In Africa a new kind of “hominid” with a top heavy brain has evolved. Behold, This Dreamer 2 million years (2359hrs) We now enter the last few seconds on the clock. A more distorted primate brain evolves as humans move through Europe and down into Asia. Eventually two types of Humans arrive in Australia. One from Java The other from Chinese origin Aborigines prevail to become the worlds most sophisticated huntergatherer.