* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Bio 1309 Early Earth History 4 Billion Years old! Horrible Place!
Document related concepts
Bio 1309 Early Earth History Slide 1 4 Billion Years old! First the earth – really inhospitable! Then the moon ! The great bombardment! Slide 2 Horrible Place! • No free Oxygen • High Radiation (no ozone yet…) (so what is ozone anyway?) • Noxious gasses with sulfur, carbon monoxides, dangerous chemicals • LOTS of volcanic activity • Water likely not buffered .. (whats a buffer?) Slide 3 1 So What changed? • Earliest bacteria – Archae made Oxygen. • Earth rusted (iron III oxides) Slide 4 Grand Canyon example Slide 5 Impact Craters! The Barringer Crater in Arizona - .74 miles across, 560 ft deep http://www.haydenplanetarium.org/tyson/read/2009/06/05/musings-of-a-solo-ist-astrophysicist-the-humanist Slide 6 2 Riding the Continents - Pangaea • Pangaea was a supercontinent that formed about 300 million years ago – It began to break apart around 200 million years ago Slide 7 Riding the Continents – Pangaea Separates • Pangaea broke into two continents: – Laurasia • Laurasia was the more northerly of the two continents – Gondwanaland • Gondwanaland was the more southerly of the two Slide 8 Riding the Continents – Jurassic Period Slide 9 3 Riding the Continents – Cretaceous Period Slide 10 Riding the Continents - Now Slide 11 Riding the Continents Slide 12 4 Riding the Continents - Evidence • Fossil evidence for Pangaea includes presence of similar and identical species on continents now great distances apart • For example, fossils of the therapsid, Lystrosaurus, found in South Africa, India and Australia Slide 13 Therapsid? Definition: • any of various groups of mammal-like reptiles of the extinct order Therapsida • inhabiting all continents from midPermian to late Triassic times • Some of which were probably warmblooded and directly ancestral to mammals. Slide 14 Pangea Examples of Organisms Slide 15 5 Riding the Continents - Range • Lystrosaurus fossils have been found together with members of the Glossopteris flora – distribution would have ranged from polar circle to equator if the continents were in their present position Slide 16 Lystrosaurus & Glossoptera Slide 17 Riding the Continents • Similarly, the freshwater reptile, Mesosaurus, has been found in only localized regions of the coasts of Brazil and West Africa Slide 18 6 Mesosaurus – Only Africa & Brazil Slide 19 Riding the Continents – Geo Evidence • Additional evidence for Pangaea found in geology of adjacent continents – Includes matching geological trends between eastern coast of South America and western coast of Africa Slide 20 South America and western coast of Africa Slide 21 7 Riding the Continents – More Data • The polar ice cap of the Carboniferous Period covered the southern end of Pangaea • Glacial deposits of till, of the same age and structure found on many separate continents that would have been together in the continent of Pangaea Slide 22 So what is Till? Till Definition: mixture of rocks, boulders, and soil picked up by a moving glacier and carried along the path of the ice advance. The glacier deposits it along its path: on the sides of the ice sheet, at the toe of the glacier when it recedes, and across valley floors when the ice sheet melts. Till deposits are like the footprint of a glacier and are used to track the movement of glaciers. Slide 23 Till Deposits Slide 24 8 Riding the Continents – Magnetic Data Paleomagnetic study of apparent polar wandering paths support theory of super-continent Orientation of magnetic minerals in rocks show movement of continental plates Slide 25 Paleomagnetism Data Slide 26 Riding the Continents- Mountains • The continuity of mountain chains provides evidence for Pangaea • One example Appalachian Mountains chain extends from northeastern United States to the Caledonides of Ireland, Britain, Greenland, and Scandinavia Slide 27 9 Mountain Data • The Appalachian Mountains chain extends from northeastern United States to the Caledonides of Ireland, Britain, Greenland, and Scandinavia! Slide 28 Mountain Data Slide 29 10