Metamorphic Rocks

Metamorphic rocks start as one kind of rock and—with pressure, heat, and time—progressively adjust right into a new form of rock.

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Metamorphic Rock Isua

Metamorphic rock, estimated to be as old as 3.8 billion years, situated near Isua at Qorqut Sound, Greenland also.

Picture by James L. Amos


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The term “metamorphosis” is many often supplied in reference to the procedure of a caterpillar altering into a butterfly. However, the word “metamorphosis” is a vast term that shows a adjust from one point to an additional. Even rocks, a seemingly continuous substance, can readjust into a brand-new type of rock. Rocks that undergo a readjust to form a new rock are described as metamorphic rocks.

In the rock cycle, there are three various forms of rocks: sedimentary, igneous, and metamorphic. Sedimentary and igneous rocks began as somepoint various other than rock. Sedimentary rocks were initially sediments, which were compacted under high press. Igneous rocks developed when liquid magma or lava—magma that has arised onto the surconfront of the Earth—cooled and hardened. A metamorphic rock, on the other hand, started as a rock—either a sedimentary, igneous, or even a different kind of metamorphic rock. Then, because of miscellaneous conditions within the Earth, the existing rock was readjusted into a brand-new kind of metamorphic rock.

The conditions forced to create a metamorphic rock are exceptionally specific. The existing rock must be exposed to high warmth, high press, or to a hot, mineral-affluent liquid. Usually, all 3 of these circumstances are met. These conditions are most frequently discovered either deep in Earth’s crust or at plate borders wbelow tectonic plates collide. In order to create metamorphic rock, it is necessary that the existing rock reprimary solid and also not melt. If tright here is also a lot heat or push, the rock will certainly melt and end up being magma. This will certainly result in the development of an igneous rock, not a metamorphic rock.

Consider just how granite transforms create. Granite is an igneous rock that forms when magma cools reasonably progressively underground. It is normally composed generally of the minerals quartz, feldspar, and also mica. When granite is based on intense heat and also push, it alters right into a metamorphic rock referred to as gneiss.

Slate is another common metamorphic rock that creates from shale. Limestone, a sedimentary rock, will adjust right into the metamorphic rock marble if the best conditions are met.

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Although metamorphic rocks generally create deep in the planet’s crust, they are regularly exposed on the surconfront of the Earth. This happens because of geologic uplift and the erosion of the rock and soil above them. At the surchallenge, metamorphic rocks will be exposed to weathering procedures and also may break down into sediment. These sediments can then be compressed to create sedimentary rocks, which would certainly begin the whole cycle abrand-new.