Year 13 Test 1 Tectonic theory

A theory explaining the structure of the Earths crust and many associated phenomena as resulting from the interaction of the rigid lithosphere

Francis Bacon observed that the coastlines of certain countries appeared to fit (West Africa and East South America) "Jigsaw Fit"

Robert Mallett was the first scientist to observe the speed at which earthquakes spread, contributing to Plate Tectonic Theory

Alfred Wegener develops theory of continental drift, the idea that the countries belonged to one super continent, "Pangea" and then drifted apart.

Laurasia in the North and Gondwanaland in the South

In S America and Africa, Mesosaurus and Glossopteris fossils found.

Discovery of Mid Atlantic Ridge thanks to sonar. Rock of recent age.

Harry Hess proposes theory of Sea floor spreading, idea that ocean floor is moving apart with lava rushing in to create new land.

Symmetric pattern on either side of MAR of differing magnetic polarity leading to conclusion that sea floor is spreading as rock pattern aligned with theorised magnetic polarity reversals.

2.5cm/yr

3-4 billion years old

200 million years

30-70km thick

5-10km thick

Granite, Felsic minerals