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PHYS 0106 (Spring, 2001) Earth History Timeline |
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| Phanerozoic Eon: Paeozoic Era: Permian Period | |||
Timeline Links Phanerozoic Neoproterozoic Mesoproterozoic Paleoproterozoic Archean Other Links Historical Geology Page Physical Geology Page Mike's Home Page |
Writer/Researcher: Kerrin Beirne Editor: Cindy Kennedy Web Page Builder: Kerrin Beirne The Paleozoic Era ended with the largest mass extinction, on both land and in water, known today. It is not clear, however, what exactly caused the extinction of 80-90% of marine species, 75% of reptiles and amphibians and many other species. One hypothesis is thought to have been a greenhouse effect. When high amounts of CO2 are released into the atmosphere, the CO2 increases the temerature and causess climate changes. During the Permian, the ocean was stagnant. The poor ciculation of the ocean caused organic matter to sink into the sediments at the bottom of the ocean floor. The breakup of Pangea caused the circulation of the ocean to pick up again, causing extra carbon from the organic matter on the ocean floor to surface and be turned into CO2. This was a contributor to increasing the amount of CO2 in the atmosphere. Volcanic eruptions released large amounts of gases into the air, including high amounts of CO2 and SO2. Continental volcanism during the Permian also contributed to the CO2 level. Evidence of volcanic activity has been discovered in Siberia, know as the Siberian Traps. These traps reveal layers of lava flows and volcanic debris at the P-T boundary. The supercontinent, Pangea, stretched from pole to pole during the Permian. Sea level dropped leaving shallow marine species without habitats. This added to the already decreasing amounts of species due to the formation of Pangea, where species faced competition with other species to survive and lack of continental shelf to live. As species died off, the remains of these species were exposed to the atmosphere, producing the oxidation of organic matter along the continental shelf, which releases CO2 into the atmosphere. When sea level drops, gas hydrates might release large amounts of CO2 and methane into the atmosphere. These gases release through sediments along the continental shelf. Such evidence led geologists to believe that a cycle of CO2 releasing into the air could have been part of the cause that devastated life at the end of the Permian. High amounts of CO2 are deadly to marine life. The CO2 literally poisoned marine inhabitants. For example, plankton almost completely diminished, leaving marine species that lived off plankton for food, died. Although animals and plants are not as affected by high levels of CO2, the massive global increase in temperature was caused by the CO2, which caused climate changes. Many species could not survive the change. Paleontologists know that the temerature rose because of the red beds that formed. The sediments rust at such temeratures and at the end of the Permian, the red beds in Karoo had an "abrupt appearence." Although theories have been made about the extinction, it is still unclear exactly what took place. New evidence has raised the question of a possible impact and the fluctuation of sea level is still a possibility, too. Until more concreat evidence can support a prediction, we are only left guessing what exactly took place. |