Geology Explained

Geologists is a science which looks at the history of Earth through the study of rocks . There are three main types of rocks which are studied sedimentary, igneous and metamorphic. The first of which are called sedimentary rocks , these are layered in appearance and are made up of rock fragments that have formed into layers, these are compressed over millions of years until eventually they are cemented together. Fossils are often found in these rocks . Examples of sedimentary rocks are mudstone, sandstone and limestone otherwise known as GEOLOGY. The fossils which are found within these rocks are usually the remains of plants and animals. The second rock type is Igneous rock, these rocks do not contain fossils within them, this is molten rock (also known as magma) which has cooled and solidified which can be converted into ENERGY. There are two types of Igneous rock the first of which is called Intrusive Igneous rock this is formed when molten rock (magma) is forced from deep underground into the outer layers of the earths crust, this slowly cools down. Extrusive Igneous rock is formed when a volcano erupts and magma cools quickly on the ground. Magma on first leaving the volcano reaches temperatures of between 700ºC and 1300ºC. Granite is an example of intrusive igneous rock. The third main type of rock is metamorphic rock – these are existing rocks which have been heated and compressed without melting. The rocks from which they were made have the same identical chemical composition. An example of this is marble this is formed from limestone , the two of which are forms of calcium carbonate. Gneiss, slate and marble are examples of these rocks . Metamorphic rock is often shiny in appearance and has small crystal like fragments running through it. Constant recycling of material in the Earths crust is taking place and the term ‘rock cycle’ is used when referring to this. Weathering of existing mountain ranges causes eroded rock to be deposited and this forms sedimentary rocks . When sedimentary rocks become buried and compressed or uplifted by large movements from the Earths crust and they are subjected to pressure and heat they could be transformed into metamorphic rocks . These metamorphic rocks may continue to be lifted and form mountain ranges, or they may sink deeper down and melt to form magma. Molten rock (magma) begins to push towards the crust by pressure. This eventually cools and solidifies forming Igneous rock. If volcanic activity causes the molten rock to be extruded from the crust this will form extrusive igneous rock on the ground. If it crystalises below the surface it will turn into intrusive igneous rock. Any type of rock can eventually reach the surface as a result of movements from the crust or mantle, these can become subject to erosion and weathering, this begins the cycle again ie. The ‘rock cycle’. The Peak district national park is a good place for Geologists this is in Derbyshire in England. The rocks around the Peak District are thought to have been laid down 300 million years ago. At that time the place we now know as the peak district was thought to be a warm sea that was about 5 – 10 degrees south of the equator. This accounts for a lot of the geological rocks we see in the Peak District today. As with the Grand Canyon this too will be a great place geologically speaking.

Tags:
 Print This Post Posted in anaerobic digestion 1 Comment