)
Fig. 118 Continental drift . The continent of Pangaea 200 million years ago.
continental drift
the theory originally put forward in 1912 by Alfred Wegener that continental masses were continuously moving over the surface of the globe as though floating on a sea of molten rock. Doubted extensively for many years, the theory is now generally accepted and supported by evidence from geomagnetic studies, the distribution of plants and animals, and the study of PLATE TECTONICS. Two hundred million years ago the present continents were joined in a universal land mass called Pangaea. Since that time, the continents have drifted apart and the study of plate tectonics shows that they are still moving. Over a period of 400 million years Britain has drifted from south of the tropic of Capricorn to its present position - over 80° of latitude. Pangaea was probably formed by previously separate continents coming together, and the Appalachian, Caledonian, Greenland and Scandinavian mountains probably resulted from North America and northern Europe coming into collision. Previous separation would account for the position of the equator and South Pole 440 million years ago.Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005