How does gneiss form from granite

It is formed by the metamorphosis of granite , or sedimentary rock. Gneiss displays distinct foliation , representing alternating layers composed of different minerals. Because of the coarseness of the foliation, the layers are often sub-parallel, i. Therefore, granite has been very important as a construction material since ancient times. It has a comparatively high density and a good compressive strength.

Moreover, this material has a poor permeability when not cracked and a strong permeability when cracked. Figure 2: Appearance of Granite. When considering the occurrence of granite, it occurs mainly in the continental crust. Sometimes we can find this material in circular depressions surrounded by a range of hills, formed by the metamorphic aureole or hornfels.

Granite is easily subjected to weathering; it undergoes physical weathering via exfoliation joints this type of weathering occurs on a large scale. We can also observe chemical weathering in this material; carbonic acid, rain and saltwater can cause chemical weathering of the rock.

High temperature and high pressure processes that act on igneous and sedimentary rocks cause the formation of gneiss while the slow crystallization of magma forms granite. There are three types of rocks as sedimentary rocks, igneous rocks, and metamorphic rocks. The main difference between gneiss and granite is that gneiss is a type of metamorphic rock, whereas granite is a type of igneous rock.

Her interest areas for writing and research include Biochemistry and Environmental Chemistry. Figure 1: Gneiss. View all posts. Usually, all three of these circumstances are met. In order to create metamorphic rock, it is vital that the existing rock remain solid and not melt. If there is too much heat or pressure, the rock will melt and become magma.

This will result in the formation of an igneous rock , not a metamorphic rock. Consider how granite changes form. Granite is an igneous rock that forms when magma cools relatively slowly underground. It is usually composed primarily of the minerals quartz, feldspar, and mica.

When granite is subjected to intense heat and pressure, it changes into a metamorphic rock called gneiss. Slate is another common metamorphic rock that forms from shale.

Limestone, a sedimentary rock , will change into the metamorphic rock marble if the right conditions are met. This happens due to geologic uplift and the erosion of the rock and soil above them. At the surface, metamorphic rocks will be exposed to weathering processes and may break down into sediment. These sediments could then be compressed to form sedimentary rocks, which would start the entire cycle anew.

Any rock type can become any other. The audio, illustrations, photos, and videos are credited beneath the media asset, except for promotional images, which generally link to another page that contains the media credit. The Rights Holder for media is the person or group credited. Tyson Brown, National Geographic Society. National Geographic Society. For information on user permissions, please read our Terms of Service.