Plate tectonics Flashcards
Define magma
It is the liquid rock in the mantle
Define endogenic forces
Forces from within the earth that cause the crust to move vertically or horizontally
What is mainly responsible for endogenic forces?
Convection currents
What are convection currents?
It is the rising, spreading and sinking of materials in the mantle as it is heated by the core.
What is the asthenosphere?
Weak and ductile part of the mantle lying below the lithosphere
What is the lithosphere?
It is the crust and the solid part of the upper mantle
What is the oceanic crust made from?
Rocks such as basalt made from silica and magnesium- very heavy rocks make it heavy
What is the continental crust made from?
Rocks such as granite are rich in silica and aluminium- lighter rocks so the crust is les heavy than oceanic
Which crust is the thinnest?
Oceanic crust is around 8km thick while the continental is much thicker at around 45km thick
Who proposed the idea of continental drift?
Alfred Wegener
What the land called when all earth continents were as one?
Pangea
Wat composed the main parts of Wegener’s theory?
Matching fossils- the same fossils were found in different continents thousands of miles apart like the Mesosaurus fossil which was found in both Africa and South America. It was a freshwater animal so could not have swam between the two land masses suggesting the continents must have been joined together.
Matching rock folds- Identical rock folds were found along the west of America and the north west of Europe coats suggesting that these were all once a mountain range that broke apart as they are identical and have the same rock type.
seafloor SPREADING-MAKES THE OCEAN FLOOR WIDER MOVING PLATES
Subduction- old seafloor is destroyed and this explains why some plates move faster than others
