![]() ![]() The ‘stripes’ on the ocean floor, it was suggested, represent different ages of oceanic basaltic rock, which have been pushed away to either side of a spreading centre and replaced by younger basaltic rock. Rock formed during a period of normal magnetism will give a positive magnetic anomaly because the rock has the same polarity as the Earth’s existing magnetic field, while rock formed during a period of reverse magnetism will give a negative magnetic anomaly. Hess and Dietz’s work played a vital role in the development of the modern theory of plate tectonics.ġ963 Vine, Matthews and Morley (VMM) suggested the idea that as new basaltic crust is created, its minerals (particularly magnetite) become magnetized in alignment with the existing magnetic field of the earth. Dietz named this idea seafloor spreading. The following year, geophysicist Robert S. This data led to the discovery of mid oceans ridges which are submarine mountain systems that encircle the planet.ġ960 Harry Hess an American geophysicist developed the idea that the Earth’s crust moves laterally away from volcanically active mid-ocean ridges. However, like Wegner, Holmes’ idea was faced with criticism but in the present day the theory has gained much support.ġ950’s Research vessels mapped the seafloor throughout this decade and as a result data on the topographic features of the ocean basin has been acquired. ![]() He argued that all of Earth’s continents were once joined together in a single landmass before drifting apart.ġ929 Arthur Holmes a British geologist proposed the idea that mantle convection is the force driving continental drift providing a mechanism to explain Wegner’s theory. ![]() this led him to publicly advocate his theory of continental drift. He analysed rock types, geological structures and fossils from each side of the Atlantic ocean and found significant similarities between the matching continents on either side of the ocean. Of course, many others played key roles in the development of the theory and in this post, I will discuss the roles of those who led to the development of a truly pivotal scientific theory.ġ596 Flemish mapmaker Abraham Ortelius noticed that the coastlines of the continents appeared to fit together and as a result, he hypothesized that they were once joined and that the Americas were “torn away” from Europe and Africa.ġ912 On the 6th of January 1912 meteorologist and geophysicist Alred Wegner proposed his theory of continental drift. Now he is regarded by many as the father of plate tectonics. At the time Wegener’s theory was widely disregarded, as he did not have an explanation for exactly how the continents moved. Plate tectonics is the modern version of the continental drift theory first proposed by Alfred Wegner in 1912. Plate tectonics is the theory that describes the large-scale movement of seven major and many minor plates across the globe. ![]()
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