Transcript Granite
Produced and Presented by Ryan Hiscoke The Rock Cycle Explained The Rock Cycle is a group of changes. Igneous rock can change into sedimentary rock or into metamorphic rock. Sedimentary rock can change into metamorphic rock or into igneous rock. Metamorphic rock can change into igneous rock or sedimentary rock. Igneous Rock Igneous rocks are sometimes called ‘the mother of all rocks’ because they are the first type of rock formed after a volcanic eruption. Igneous rocks are formed when magma breaks through the crust and pours lava over the surface. When this cools it forms hard rock known as igneous rock. Granite is an example of an igneous rock and the size of its crystals tells us how quickly it cooled. If the magma in the underground pockets cool slowly the crystals will be large. But if the lava above ground cools quickly small crystals will form. Igneous rocks are hard and always have crystals in them. Igneous rocks never have fossils in them because they come from magma and anything near it would disintegrate Some examples of how different types of Igneous rock were formed Pumice Pumice rocks are igneous rocks which were formed when lava cooled quickly above ground. You can see where little pockets of air had been. This rock is so light, that many pumice rocks will actually float in water. Pumice is actually a kind of glass and not a mixture of minerals. Because this rock is so light, it is used quite often as a decorative landscape stone. Ground to a powder, it is used as an abrasive in polish compounds and in Lava soap. Granite Granite rocks are igneous rocks, which were formed by slowly cooling pockets of magma that were trapped beneath the earth's surface. Granite is used for long lasting monuments and for trim and decoration on buildings Sedimentary Rock When Rocks erode and become washed away. The particles are called sediment. These little particles of sediment are washed downstream where they eventually settle to the bottom of the rivers, lakes, and oceans. Layer after layer of sediment is deposited on top of each other. Over time these layers are compressed down more and more through time, until the bottom layers slowly turn into rock. Some examples of sedimentary rock and their uses Gypsum Gypsum rocks are sedimentary rocks made up of sulphate mineral and formed as the result of evaporating seawater in massive prehistoric basins. It is very soft and is used to make Plaster of Paris, casts, melds, and wallboards. Limestone Limestone rocks are sedimentary rocks that are made from the mineral calcite, which came from the beds of evaporated seas and lakes and from sea animal shells. This rock is used in concrete and is an excellent building stone for humid regions. Sandstone Sandstone rocks are sedimentary rocks made from small grains of the minerals quartz and feldspar. They often form in layers as seen in this picture. They are often used as building stones. Metamorphic rock Metamorphic means ‘change in form’. Sometimes igneous and sedimentary rocks may get buried deep underground. The heat and pressure of Earth ‘cooks’ and twists the rock. It changes into a new type of metamorphic rock. If you examine metamorphic rock samples closely, you'll see how flattened some of the grains in the rock are. Some examples of how different types of Metamorphic rock were formed Gneiss These rocks may have been granite, which is an igneous rock, but heat and pressure changed it. You can see how the mineral grains in the rock were flattened through tremendous heat and pressure and are arranged in alternating patterns. Schist These rocks can be formed from basalt, an igneous rock like shale, a sedimentary rock or a metamorphic rock like slate. Through tremendous heat and pressure, these rocks were transformed into this new kind of rock.