EESA06H3 Lecture Notes - Lecture 4: Viscosity, Subduction, Mantle Plume
Document Summary
Any type of rock can change into any other type of rock. If you cool molten magma, you end up with igneous rocks. If rock gets worn down by forces of erosion, it breaks down into sediments, which are transported and become sedimentary rock. If rock get subjected to a lot of pressure it becomes metamorphic. The source of igneous rocks is always magma. Basaltic magma is rich in iron and magnesium and is what the ocean floor is made up of. Difference between magma and lava-> once it comes out of a volcano it is lava; inside the earth it is magma. Igneous rocks can cool in two ways: volcanic/extrusive come out of the earth, intrusive/plutonic cool under the earth; can only see if the rocks on top of them are eroded away. The size of the crystals tells you how long it had to cool down; big crystals cool slowly and small, fine crystals cool quickly.
