Plate tectonics (Part 1): What are they?

Helen Gould (UK) What does “plate tectonics” really mean? The Earth’s surface bears about 20 plates, which are able, over millions of years, to move about on layers beneath the crust. Some of the surfaces of these plates consist of continental crust, some of oceanic crust, some both (Fig. 1). Fig. 1. Map of the tectonic plates of the Earth. Who came up with the idea? The idea didn’t develop overnight as a result of one person’s efforts. In 1915, Alfred Wegener suggested “continental drift”, in which the continents moved around on the Earth’s surface. Arthur Holmes later suggested continents could be moved by convection currents in the mantle, fuelled by the heat of radioactive decay. Harry Hess was an American geologist who came up with the idea of seafloor spreading. In the 1960s, J Tuzo Wilson developed the convection current idea further, proposed “hot spots” and “plates” and, in 1963, Fred Vine and Drummond Matthews proved the existence of seafloor spreading using “magnetic striping”. What proof is there that plate tectonics really exists? The fit of continents against each other, particularly Africa and South America, shows that they were once joined (Fig. 2). This branch of geology – palaeogeography – has led to the detection of several ancient supercontinents and oceans. Their existence is supported by matching similar geological features, such as ancient crystalline rocks and glaciated areas, in adjacent regions of South America and Africa, and North America and Europe. Two massive continents, which existed in the past, … Read More

To access this post, you must purchase Annual subscription, 12 Month Subscription or Monthly subscription.
%d bloggers like this: