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The concept of continental drift was first proposed by Alfred Wegener. In 1912 he noticed that the shapes of continents on either side of the Atlantic Ocean seem to fit together (for example, Africa and South America). Benjamin Franklin and others had noted much the same thing earlier. The similarity of southern continent fossil faunas and some geological formations had led a relatively small number of Southern hemisphere geologists to conjecture as early as 1900 that all the continents had once been joined into a supercontinent. The concept was initially ridiculed by most geologists, who felt that an explanation of how a continent drifted was a prerequisite and that the lack of one made the idea of drifting continents wholly unreasonable. The idea of continental drift did not become widely accepted as theory until the 1950s in Europe. By the 1960s, geological research conducted by Robert Dietz , Bruce Heezen, and Harry Hess led to acceptance among North American geologists.The hypothesis of continental drift became part of the larger theory of plate tectonics. This article deals mainly with the historical development of the continental drift hypothesis before 1950. See: plate tectonics for information on current ideas underlying concepts of continental drift.
1 Various Data
South America and Africa are moving apart at 3 cm per year, due to the seafloor spreading along the Mid-Atlantic RidgeCourtesy USGS The Mid-Atlantic Ridge is an underwater mountain range of the Atlantic Ocean that runs from Iceland to Antarctica, and is the longest mountain range on Earth. The ridge was discovered by Bruce Heezen in the 1950s. The discovery of this ridge.
2 Evidence for continental drift
Note: this section needs some work, as it should concentrate on evidence available to Wegener and contemporaries, not modern evidence.
Evidence for continental drift is now extensive, in the form of plant and animal fossils of the same age found around different continent shores, suggesting that these shores were once joined. For example the fossils of the freshwater crocodileCrocodylus Osteolaemus Tomistoma A crocodile can be any of the 14 species of large, water-loving reptiles in the family Crocodylidae (sometimes classified instead as the subfamily Crocodylinae . The term is also used more loosely to include all members of found in Brazil and South Africa. Another illustrative example is the discovery of fossils of the aquatic reptileCrocodilia Crocodilians Rhynchocephalia Tuataras Squamata Suborder Sauria Lizards Suborder Serpentes Snakes Testudines Turtles Superorder Dinosauria Saurischia Ornithischia The reptiles are a group of vertebrate animals. Most reptiles are tetrapods, and t Lystrosaurus from rockRock is a substance composed of minerals and classified according to mineral composition. Rocks are generally clasified by the processes that formed them, and are thus separated into igneous, sedimentary, and metamorphic rocks. Igneous rocks are formed frs of the same age from locations in South AmericaSouth America is a continent crossed by the equator, with most of its area in the Southern Hemisphere. South America is situated between the Pacific Ocean and the Atlantic Ocean. It became attached to North America only recently, geologically speaking, wi, AfricaAfrica is the world's second-largest continent in both area and population, after Asia. 30,244,050 km2 (11,677,240 mi2) including the islands, it covers 20. 3% of the total land area on Earth, and with over 800 million human inhabitants it accounts for ar, and AntarcticaAntarctica (from Greek nu;ταρκτικ&sigmaf opposed to the arctic) is a continent surrounding the Earth's South Pole. It is the coldest place on earth and is almost entirely covered by ice. It is not to be confused with the. There is also living evidence - the same animals being found on two continents. An example of this is a particular earthwormEarthworm is the common reference for the larger members of the Oligochaeta (which is either a class or subclass depending on the author) in the phylum Annelida. In classical systems they were placed in the order Opisthopora on the basis of the male pores found in South America and South Africa.
There exist two main forms of more geological evidence evident: rock sequences and magnetic stripes. When the rock strata of the tips of separate continents are very similar it suggests that these rocks were formed in the same way implying that they were joined initially. For instance, some parts of Scotland contain rocks very similar to those found in eastern North America. The second piece of evidence arises when the rocks were formed from magma erupting out of a volcano. When this happens the iron particles align with Earth's magnetic field and set in this position. As the earth's magnetic field flips every half-million years, strips of land of alternating magnetic orientation are formed - symmetrical from the volcano. This showed how some plates are moving away from each other.
The complementary shapes of the facing sides of South America and Africa is obvious, but is a temporary coincidence. In millions of years, seafloor spreading, continental drift, and other forces of tectonophysics will further separate and rotate those two continents. It was this temporary feature which inspired Alfred Wegener to study what he defined as continental drift.
