Compositional vs. Mechanical Water and oil Water and ice

Compositional Layer (Water and ?) Crust : oceanic-crust & continental crust Mantle Predicted by the behaviour of seismic waves Confirmed by rock samples Core-mantle boundary, composition changes again Seismic waves suggest very high density material  metals rather than rock Presence of a magnetic field around the earth also indicates molten metallic core

Mechanical Layer (Water and ?) Because of plate tectonics theory, plates had to be thicker than just the crust Plates: crust acting together with the uppermost part of the mantle  lithosphere Rigid lithospheric plates "float" on aesthenosphere (partially molten, not liquid)

Mechanical Layer (Water and ?) Great pressure  solid part of mantle  mesosphere Lithospheric mantle, aesthenosphere, and mesosphere same composition but mechanical properties different Geologists often refer to the aesthenosphere as the jelly in between two pieces of bread: the lithosphere and mesosphere Inner and outer core. Outer core is liquid molten metal Inner core is solid Composition of core different from mantle, possible to remain a liquid at much higher pressures

Evidence for the Continental Drift Theory

Biology Mesosaurus, small reptile Found living in South Africa and Brazil Plant existed when coal was being formed only located in India and Antarctica

Geology Rocks of similar type, age, formation and structure in south-east Brazil and South Africa Appalachian Mountains of eastern USA correspond geologically with mountains in northwest Europe

Climatology Coal formed under warm, wet conditions found beneath Antarctica icecap Evidence of glaciation had been noted in tropical Brazil and central India Coal, sandstone and limestone could not have been formed in Britain with its present climate