Before the 1960s, most geologists were adamant that the continents were stationary. A handful promoted the notion that the continents had moved (continental drift), but they were accused by the majority of indulging in pseudo-scientific fantasy.
Today, that opinion has reversed – plate tectonics, incorporating continental drift, is the ruling theory.
Geologists put forward several lines of evidence that the continents were once joined together and have moved apart, including:
The current theory that incorporates sea-floor spreading and continental drift is known as ‘plate tectonics’.
The general principles of plate tectonic theory may be stated as follows.1 The earth’s surface consists of a mosaic of rigid plates, each moving relative to adjacent plates. Deformation occurs at the edges of the plates by three types of horizontal motion; extension (or rifting, moving apart), transform faulting (horizontal slipping along a fault line), and compression, mostly by subduction (one plate plunging beneath another).
Extension occurs as the sea floor pulls apart at rifts, or splits.
Transform faulting occurs where one plate slips horizontally past another (e.g., the San Andreas Fault of California).
Compressional deformation occurs when one plate sub-ducts beneath another, e.g., the Pacific Plate beneath Japan and the Cocos Plate beneath South America, or when two continental plates collide to produce a mountain range, e.g., the Indian-Australian Plate colliding with the Eurasian Plate to form the Himalayan Mountains. Volcanoes often occur in regions of subduction.
Batten D., Ham K., Sarfati J., Wieland C., The Answer Book Pg 147 – 148.
1. Nevins, S.E. [Austin, S.A.], 1987. Continental drift, plate tectonics, and the Bible. In: Up with Creation! D.R. Gish, and D.H. Rohrer (eds.), Creation Life Publishers, San Diego, pp.173-180. See also Longman Illustrated Dictionary of Geology, Longman Group, Essex, UK, 1982, pp 137-172.