* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download devonian presentation
Survey
Document related concepts
Spherical Earth wikipedia , lookup
History of geomagnetism wikipedia , lookup
Paleontology wikipedia , lookup
Schiehallion experiment wikipedia , lookup
Anoxic event wikipedia , lookup
Age of the Earth wikipedia , lookup
History of climate change science wikipedia , lookup
History of geology wikipedia , lookup
Tectonic–climatic interaction wikipedia , lookup
History of Earth wikipedia , lookup
Future of Earth wikipedia , lookup
Transcript
The End of the Devonian Period: A Mass Extinction Alexandra Allen San Francisco Sate University Earth Science Department Life Flourishes Throughout the Period: During the Devonian, a majority of the Earth was covered in a vast ocean, giving marine life the ability to evolve and thrive. Some species hat evolved in the Devonian were the first of their kind such as: Ammanoid Cephlapods Gnathostomes Siliceous Sponges Life Flourishes Throughout the Period: And many other species evolved and expanded, including: Spiny Acanthodians Osteichthyans Placoderms Chondrichthyan Fish Sacopterygians Actinopterygians Trilobites Mass Extinction of Marine Life: The Devonian Period ends with a series of mass extinctions that wipe out nearly 70% of all invertebrate species. Tropical marine species suffered the most loss, followed by freshwater species. The Devonian extinction occurred over a period of 20 million years, leading paleoscientists to speculate on the causes. There are two theories as to the domino effect of Devonian Extinctions… Both based on the idea that expanding erogenous plants decreased the amount of Carbon Dioxide in the atmosphere, leading to a cooling planet, and eventually, glaciation of the Southern Pole. Devonian Extinction Theories: Cooling of Earth due to CO2 Decreases 1) Chemical Weathering- This process creates Calcium and Magnesium, removing CO2 from the atmosphere, and cooling Earth. 2) Carbon Storage- Plants convert CO2 to Carbon which is then stored inside the plant structure. When it dies, the Carbon is released into soils. Through weathering, CO2 is again removed from the atmosphere effectively cooling the Earth. Why does the Earth Cooling and Glaciation matter?