Presentation on theme: "The Australian Environment before Human Habitation Mat Hyland Notre Dame College."— Presentation transcript:
The Australian Environment before Human Habitation Mat Hyland Notre Dame College
Introduction n 4.6 billion years ago the earth was formed n Humans (Aboriginals) arrived in Australia approx. 46 000 years ago. n Europeans arrived 212 years ago (1788)
The 24 hour clock! n 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) n At 2.00am on the clock the planet is still in the process of birth. The seeds are being sown. n 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. n 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) n At 6.00am on the clock our solar system was born and planets start to orbit the sun. n Carbon atoms link to other atoms of which some can replicate. n 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) n At 11.00am the world is warm and cloudy and its surface is largely covered by shallow seas. n Each day (one revolution) lasts only 18 hours. n Australia at this stage consists of two major landmasses lying relatively close to each other somewhere near the north pole. n Bacteria have proliferated to trigger major environmental change.
Invaders 450 million years to 350 years (2139hrs - 2210yrs) n Land is still barren n Some algae have adapted to occasional exposure to air (O 2 ). n With the aid of root cells and vascular stems these algae colonise the shoreline. n Miniature forests entice animals to follow. The first of these are millipede- like 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) n Pangaea is formed. (All the earths land massess accumulate on one side of the earth distupting global weather patterns). n At 10.20pm climates become erratic and a new ice age is born. n Crustal drift carries Gondwana (the southern half of Pangaea) from one side of the pole to the other. n Migration of polar ice carves is way across five continents.
n Almost all life forms are extinguished. n However many new species appear. n Two survival techniques to emerge are the “seed” and the “egg”.
Stirring the Stew 200 million years to 130 million years (2257hrs - 2319hrs) n At 11.00pm most of the surface is already inhabited by a multitude of forms that are complex and well adapted to their environments. n The day is slightly shorter than ours, the climate is warmer and there is little or no snow, even at the poles. n Ancient conifers now dominate hill sides.
n Ferns and tree ferns clothe the valleys. n 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) n At 11.20pm a comet bursts out of the southern skies and plunges to earth in the very centre of Australia. n Flooding is widespread cause of high sea levels. n Life is thriving. n Conifer, cyad and tree fern forests cover Australian & Antarctica supporting a large dinosaur population. n The evolution of the flower begins.
Last Exit 65 million years to 53 million years (2340hrs - 2344hrs) n In the last twenty minutes of our time scale, temperatures take their first serious plunge since the previous ice age. n Vegetation everywhere undergoes massive change and a series of extinctions begins to sweep through the animal kingdom. This includes the disappearance of the dinosaurs. n Anatarctica begins to separate from Australia after a billion years.
Great Southern Ark 53 million years to 20 million years (2344hrs - 2354hrs) n Birds and Mammals now dominate as Australia recovers from one of the worst series of extinctions in its history. n As the temperatures continue to descend another ice age exists. n Australia drifts north towards the tropics. n Plants and animals are forced to look at defence mechanisms. They must adjust to a new climate and a shift in Latitude of 25 0
Gathering Storm 20 million years to 5 million years (2354hrs - 2358hrs) n Australia northern edge ploughs into the Pacific Ocean Plate, pushing up a series of islands known as New Guinea Highlands. n With about four and a half minutes to go, polar temperatures take another plunge. n 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) n With 90 secs to go the climate is much like it is today. n Giant mammals thrive all over the world, however in Australia this is limited due to lack of water. Large birds survive well. n Huge flocks of pelicans, flamingoes, swans, ducks and other large water birds all congregate around the shrinking remnants of ancient inland lakes. n With 30 secs to go, world temperatures take a final plunge into yet another ice age.
n In Africa a new kind of “hominid” with a top heavy brain has evolved.
Behold, This Dreamer 2 million years (2359hrs) n We now enter the last few seconds on the clock. n A more distorted primate brain evolves as humans move through Europe and down into Asia. n Eventually two types of Humans arrive in Australia. F One from Java F The other from Chinese origin n Aborigines prevail to become the worlds most sophisticated hunter- gatherer.