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This History of Life. Questions to ponder. Where did we come from? How did the Earth created or come to be?. Theories. Big Bang theory Creation. Big Bang Theory.
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Questions to ponder • Where did we come from? • How did the Earth created or come to be?
Theories • Big Bang theory • Creation
Big Bang Theory • Big Bang - The Big Bang Theory is the dominant scientific theory about the origin of the universe. According to the big bang, the universe was created sometime between 10 billion and 20 billion years ago from a cosmic explosion that hurled matter and in all directions
Creationism • Divine origin - (Earth and life was not spontaneous and placed here by creator)
Earth • 4.6 billion years old (radiometric dating) • Current population 7,206,766,000 • 261 born every minute • Year 1000 = 310 million (current US pop.) • 1900 = 1.6 billion • 2050 = 9 billion • Life first appeared on Earth between 3.9 – 3.5 billion years ago.
Birth of Earth • Earth was one big ball of magma • Meteorites hit the Earth causing heat • Volcanoes emit gases creating atmosphere (H20, CO2, S02, CO, H2S, HCN, N2, H2) http://www.youtube.com/watch?v=Tz8ithgTBj4
Clues in rocks • Earth cooled and water formed oceans • 500 millions of years ago, life first appeared • Earliest clues date 3.5 billion years ago • Records in fossils: Trace, Molds/Casts, Replacement, Petrified, Amber, Original material)
Pangea • In 1915, a geologist named Alfred Wagner came up the theory of Continental drift. This theory states that parts of the Earth's crust slowly drift atop a liquid core. Fossils records found, support the theory of continental drift and plate tectonics. Pangea started as one big super continent then during the Jurassic period broke up into two smaller super continents.
Geological Time Scale • Model that expresses the major geological and biological events in Earth’s history. • Divided into Precambrian and Phanerozoic eon. • Era – next largest division • Period – each era divided into one or more periods
Dinosaurs • What happened to them? • Theories: • Volcanism • Plate tectonics (earthquakes) • Disease • Alvarez Asteroid Theory (The asteroid hit the Earth. Research found a likely candidate for the crater at Chicxulub, on the Yucatan Peninsula of Mexico.) • http://www.youtube.com/watch?v=Y8Ij9xboreA
Mass Extinction • 1. End Ordovician (~445 Ma); ~12% of families, ~ 65% species; large glaciation/sea level fall?? • 2. Late Devonian (~365 Ma); ~ 14% of families, ~ 72% species; impact (Siljan Crater)? • 3. End Permian (~250 Ma); ~ 52 % families, >90% species; impact (Bedout Crater)?; flood basalts (Siberia); one continent; global warming; low oxygen conditions • 4. End Triassic (~210 Ma); ~ 12% families, ~ 65% species; impact (Manicouagan Crater); flood basalts (Central Atlantic) • 5. End Cretaceous (65 Ma); ~11% families, ~ 62% species; impact (Chixculub