Continental Drift Is Unlikely to Have Toaken Place. Discuss.

Only available on StudyMode
  • Topic: Plate tectonics, Mid-Atlantic Ridge, Mid-ocean ridge
  • Pages : 6 (2398 words )
  • Download(s) : 72
  • Published : May 13, 2013
Open Document
Text Preview
Continental drift is a theory stating that the Earth's continents have been joined together and have moved away from each other at different times in the Earth's history. The theory was first proposed by Alfred Wegener in 1912. Whilst his general idea of continental movement eventually became widely accepted, his explanation for the mechanism of the movement has been supplanted by the theory of plant tectonics. However there was a problem in accepting this idea originally because Wegener had no convincing mechanism or solid evidence for how the continents might move. Wegener had originally thought that the continents were through the surface of the earth's crust, like icebreakers plowing through ice sheets, and that centrifugal and tidal force were responsible for moving the continents. Opponents of the idea of continental drift noted that plowing through oceanic crust would distort continents beyond recognition, and that centrifugal and tidal forces were far too weak to move continents ,one scientist calculated that a tidal force strong enough to move continents would cause the Earth to stop rotating in less than one year. Sir Harold Jeffreys was a strong opponent of continental drift. For him, continental drift was "out of the question" because no force even remotely strong enough to move the continents across the Earth's surface was evident, this made a lot of people side with him as he was a highly recognized man with many titles, including winning a prize in 1937 of the Gold Medal of the Royal Astronomical Society . Another problem was that flaws in Wegener's original data caused him to make some incorrect and outlandish predictions: he suggested that North America and Europe were moving apart at over 250 cm per year (about 10 times the fastest rates seen today, and about a hundred times faster than the measured rate for North America and Europe). There were scientists who supported Wegener: the South African geologist Alexander Du Toit supported it as an explanation for the close similarity of strata and fossils between Africa and South America, and the Swiss geologist Emile Argand saw continental collisions as the best explanation for the folded and buckled layer that he observed in the Swiss Alps. Wegener's theory found more scattered support after his death, but the majority of geologists continued to believe in static continents and land bridges. However, it was valantine, a marine biologist that proved that a super continent did exist through the study of coral; there was abundant collectin of coral diversities millions of years back compared with the range we have today. This helps to understand the size of this super continent as coral can only live in the shallow waters, where sunlight can reach it. So the coastline must have been larger, and there was huge areas of shallow water. Eduard Suess claimed in 1885 that the ancient broken continent he named Gondwanaland—fragments that make up India, Africa, Antarctica and South America had once been connected by land bridges. A land bridge is a connection between landmasses that comes and goes. A land bridge that we all think of today connects Alaska with Siberia when the sea level is low as it did during the recent ice ages. When the polar ice caps take water from the ocean, much of the Bering Sea, including the Bering Strait, becomes dry land. Geologists have named this new land bridge Beringia. Similar land bridges are postulated between Britain and Europe, between New Guinea and Australia, between the Philippines and Indonesia, between Sri Lanka and India, and between the Southeast Asian mainland and the Indonesian islands. A land bridge is like a real bridge not everything can cross it. Beringia, for instance, is too cold to serve as a highway for palm trees or any other tree. Carnivores won't move where the animals they feed on can't go. The main species of interest when we consider the ice-age land bridges is Homo sapiens, which invaded many areas during...
tracking img