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