The Gaian Theory Essay, Research Paper

Introduction

Continental impetus is the theory that the places of the Earth & # 8217 ; s continents have moved considerable distances throughout geologic clip. A German meteorologist, by the name of Alfred Wegener, proposed the first comprehensive theory of Continental impetus in 1912. He based it on the manner the continents fit together on the opposing Atlantic seashores every bit good as the palaeontology correlativity on both sides of the Atlantic. The theory he proposed, stated that, 200 million old ages ago there was one big continent, or supercontinent, called Pangaea ; Pangaea split into two big land masss called, Laurasia and Gondwanaland. ( Plummer 460 )

During the Mesozoic epoch, Laurasia and Gondwanaland broke apart in some countries and drifted farther off from their old places In this procedure, the Earth & # 8217 ; s rotary motion caused horizontal changes in the granite continents drifting on the sea of the basaltic ocean floors. The frictional retarding force along the taking borders of the drifting continents created mountains. Wegener & # 8217 ; s theory met contention until 1954, when British geophysicists seeking to explicate the phenomenon of polar rolling revived it. ( Plummer 460 )

Around the same clip that geologists were once more going interested in the thought of traveling continents, a geologist at Princeton University, by the name of Harry Hess came up with the theory of sea floor distributing in 1962. Hess & # 8217 ; s theory provinces that the sea floor moves off from the mid-oceanic ridge as a consequence of mantle convection. This theory clearly contrasted with Wegener & # 8217 ; s early theory of Continental impetus, except for Wegener believed that the sea floor remained stationary while the continents moved through it. In the late 1960 & # 8217 ; s the theory of Plate Tectonics evolved from the two

preexisting thoughts of Continental impetus and sea floor spreading. ( Plummer 465 )

Geologists and life scientists have traditionally thought of life as holding adapted to

alterations in the environmental conditions over clip, but a new position of the Earth has emerged from what is now called the Gaia theory. Many scientists now look at the full Earth as an being ; where life and inanimate affair evolve together keeping an environment about ideal for life.

Gaia and Plate Tectonics Working Together

The Gaia theory maintains, that shortly after the formation of life, beings began to alter the environment, every bit good as adapt to the environment. One illustration of Gaian ordinance is in the Earth & # 8217 ; s care of a comparatively changeless atmospheric temperature since life began. The Earth & # 8217 ; s planetary temperature has remained comparatively changeless sing the Sun gives off 30 per centum more heat to the Earth compared to four eons ago. One regulator in cut downing planetary temperature is the transition of C dioxide and H2O in the presence of visible radiation into saccharides and O. As the sum of light making the Earth has increased, the rate of photosynthesis increased, thereby taking CO2 and chilling the planet. Another regulator is the storage of CO2 in Ca carbonate in the shells of limestone bring forthing beings. This control of planetary temperature has been critical in Gaian ordinance of the planet. ( Anderson,348 )

One more illustration of how the Earth and the biosphere may hold evolved is in its dependance and possible influence on home base tectonics. It & # 8217 ; s reasonably obvious that home base tectonics has a great consequence on the biology, but the hypothesis that the biology has altered home base tectonics is still in its babyhood. Some scientists believe that home base tectonics can merely happen on a planet that has a moderate surface temperature. High surface temperatures, such as those found on Venus, & # 8220 ; prefer the development of a midst, floaty crust. & # 8221 ; ( Stolz,50 ) In order for home base tectonics to work, the home bases must be thin plenty and dense plenty to interrupt and subduct. For this to be true, so it besides must be true that life has an influence on home base tectonics. If today & # 8217 ; s C dioxide degrees were comparable to the degrees before life became abundant, so we would hold a significantly warmer surface temperature, perchance warm plenty to forestall home base tectonics. ( Stolz,77 ) The impact of life on home base tectonics, although bad, would likely be significant.. The atmospheric composing would about be 98 per centum CO2, if the Earth were wastes of any life signifiers. That is approximately the same as on Venus. The presence of big sums of CO2 in the atmosphere four billion old ages go was necessary to forestall the oceans from stop deading through. However, if this degree of CO2 were present in today & # 8217 ; s atmosphere, the increased insularity would convey the atmospheric temperatures to 290. F. , or 50. C. ; doing the oceans to boil off and doing the planet everlastingly dry, being comparable to Venus.

It has frequently been suggested that life originated on the Earth because of a happenstance between

the narrow temperature interval over which H2O is liquid and the temperature extremes that really happen on the Earth. The Earth seemingly is besides exceeding in holding active home base tectonics. If the C dioxide in the ambiance of Venus could turn into limestone, the surface temperatures and those in the upper mantle would drop. The basalt-eclogite stage alteration would migrate to shoal deepnesss, doing the lower portion of the crust to go unstable. Therefore there is the interesting possibility that plate tectonics may be on the Earth because limestone-generating life evolves here. ( Nisbet,54 )

The primary ground limestone forming beings are sometimes credited with

leting home base tectonics to happen on Earth is that they consume C dioxide, change overing it to calcium carbonate in their shells. When the being dice, the shells sink to the underside of the ocean and are bit by bit buried. Eventually, some of the C dioxide is returned to the ambiance through volcanic activity, but the net consequence is a decrease in C dioxide in the ambiance. There is no observation or experiments to back up this, but there is one other hypothesis that states that the weight of these beings, largely stromatolites, depressed the pelagic crust sufficiently to do subduction. This seems instead improbable, nevertheless, and unless more grounds is gathered back uping this hypothesis, it will likely ne’er be taken earnestly. ( Stolz,39 )

The presence of H2O in the liquid province is besides critical to plate tectonics every bit good as life. Water plays an of import function in home base tectonics in that as magma rises, H2O permeates the pores of the hardening stone. This happens at such a rate that, on the modern Earth, a volume of H2O approximately tantamount to the entire volume of the oceans passes through the new lava about one time every ten million old ages ; which is a comparatively short clip, geologically talking. In the distant yesteryear, the rate of cycling known as hydrothermal circulation, was likely much greater. ( Westbroek,322 ) This procedure is important to both home base tectonics and life, as the H2O in the stone helps the stone to run once more at a lower temperature, and it controls the chemical science of the H2O. These facts suggest that if plate tectonics were non active, the oceans might hold become excessively toxic to back up life. ( Lovelock,134 )

Decision

This information clearly states that there is some type of relationship between life and home base tectonics. There is the indicant that a crude home base tectonics was in consequence before Gaian ordinance began, but there is important grounds that life has kept the procedure traveling. It seems that the presence of life, and the high surface temperature would do the crust to bit by bit inspissate and go more floaty, thereby doing subduction unlikely. Likewise, without home base tectonics the land would hold become unfertile and the oceans may hold become toxic, therefore likely forestalling the continual being of life on Earth. ( Ages 1991 )

It & # 8217 ; s hard, if non impossible, to divide the statement of how life effects plate tectonics from the statement of how plate tectonics affects life. One can conceive of what the Earth might be like if plate tectonics were non active here. Pangea was likely comparatively featureless, and if the Earth & # 8217 ; s crust were stationary, it would doubtless stay level. In add-on, enduring and eroding would rapidly convey the continent to sea degree, and finally the tides would scatter the deposit across the ocean floor ( Possibly like an Atlantis consequence ) . The absence of home base tectonics would enormously impact life on Earth. There is a good opportunity that life could hold formed in the oceans in the absence of home base tectonics, but it might non hold persisted. It is dubious that life would of all time hold been able to last on land. The actions of enduring and eroding, invariably rinsing critical foods into the sea, and a deficiency of some sort of mechanism for returning those foods back to the land, the stone would go incapable of back uping life.

Plants Cited

Anderson, Don L. The Earth as a Planet: Paradigms and Paradoxes. Science. January,

1984 ) : 347-354.

Lovelock, James E.. Gaia: A New Look at Life on Earth. Oxford: Oxford University

Imperativeness, 1979.

Nisbet, E. G. Living Earth: A Short History of Life and Its Home. New York:

Harper Collins Academic, 1991.

Plummer, Charles C. , McGeary, David, Carlson, Diane H.. Physical Geology Eighth Edition. McGraw-Hill.1999. 460-492

Stolz, John F. Biomineralization and Gaia Scientists on Gaia. Cambridge: The MIT

Imperativeness, 1991.

The Ages of Gaia: A Biography of Our Populating Earth. New York: Bantam Books, 1988.

Westbroek, Peter. Life as a Geological Force: Dynamicss of the Earth. New York: W. W.

Norton and Company, 1991.