The Gaian Theory Essay Research Paper IntroductionContinental

  • Просмотров 132
  • Скачиваний 5
  • Размер файла 16
    Кб

The Gaian Theory Essay, Research Paper Introduction Continental drift is the theory that the positions of the earth’s continents have moved considerable distances throughout geologic time. A German meteorologist, by the name of Alfred Wegener, proposed the first comprehensive theory of continental drift in 1912. He based it on the way the continents fit together on the opposing Atlantic coasts as well as the paleontology correlation on both sides of the Atlantic. The theory he proposed, stated that, 200 million years ago there was one large continent, or supercontinent, called Pangaea; Pangaea split into two large landmasses called, Laurasia and Gondwanaland.(Plummer 460) During the Mesozoic era, Laurasia and Gondwanaland broke apart in some areas and drifted further away

from their previous positions In this process, the Earth’s rotation caused horizontal alterations in the granite continents floating on the sea of the basaltic ocean floors. The frictional drag along the leading edges of the drifting continents created mountains. Wegener’s theory met controversy until 1954, when British geophysicists seeking to explain the phenomenon of polar wandering revived it. (Plummer 460) Around the same time that geologists were again becoming interested in the idea of moving continents, a geologist at Princeton University, by the name of Harry Hess came up with the theory of sea floor spreading in 1962. Hess’s theory states that the sea floor moves away from the mid-oceanic ridge as a result of mantle convection. This theory clearly contrasted with

Wegener’s early theory of continental drift, except for Wegener believed that the sea floor remained stationary while the continents moved through it. In the late 1960’s the theory of Plate Tectonics evolved from the two preexisting ideas of continental drift and sea floor spreading.(Plummer 465) Geologists and biologists have traditionally thought of life as having adapted to changes in the environmental conditions over time, but a new view of the earth has emerged from what is now called the Gaia theory. Many scientists now look at the entire earth as an organism; where living and nonliving matter evolve together maintaining an environment nearly ideal for life. Gaia and Plate Tectonics Working Together The Gaia theory maintains, that soon after the formation of life,

organisms began to change the environment, as well as adapt to the environment. One example of Gaian regulation is in the earth’s maintenance of a relatively constant atmospheric temperature since life began. The Earth’s global temperature has remained relatively constant considering the sun gives off 30 percent more heat to the earth compared to four eons ago. One regulator in reducing global temperature is the conversion of carbon dioxide and water in the presence of light into carbohydrates and oxygen. As the amount of light reaching the earth has increased, the rate of photosynthesis increased, thereby removing CO2 and cooling the planet. Another regulator is the storage of CO2 in calcium carbonate in the shells of limestone producing organisms. This control of global

temperature has been critical in Gaian regulation of the planet.(Anderson,348) One more example of how the earth and the biosphere may have evolved is in its dependence and possible influence on plate tectonics. It’s fairly obvious that plate tectonics has a great effect on the biota, but the hypothesis that the biota has altered plate tectonics is still in its infancy. Some scientists believe that plate tectonics can only occur on a planet that has a moderate surface temperature. High surface temperatures, such as those found on Venus, “favor the development of a thick, buoyant crust.”( Stolz,50 ) In order for plate tectonics to work, the plates must be thin enough and dense enough to break and subduct. For this to be true, then it also must be true that life has an