The rock cycle is a process that goes on forever. Igneous rocks are formed from the cooling of magma. Igneous rocks can be either extrusive or intrusive based on how fast or slow the magma cools. Intrusive rocks are formed from slow cooling of the magma; this allows crystals to form throughout the rock. Extrusive rocks form quickly usually above the surface so there is no time for visible crystals to form. Sedimentary rocks are usually formed when weathering of igneous, metamorphic or sedimentary rocks occurs and parts of the rock are broken off. These pieces of rocks often make their way into bodies of water and so fossils can often be found in sedimentary rocks. Metamorphic rocks are created below the crust when igneous rocks, sedimentary rocks or other metamorphic rocks are forced beneath the crust due to the shifting of plates. Tectonic plates are always moving so when these to plates collide, a mountain or volcano is formed or one of the tectonic plates forces the other one into the crust. Here the rocks below the surface are heated and applied with great amounts of pressure. If the rocks melt then new igneous rocks are formed, but when just the right amount of pressure and heat is applied a metamorphic rock is created. So with out the plate tectonics, no rock cycle could occur because no movement would be taking place. Therefore we would either have no rocks or the rocks would never change.
No comments:
Post a Comment