Earth Sciences 2281A/B Chapter Notes - Chapter 7: Igneous Rock, Protolith, Differential Stress
23 Feb 2019
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Document Summary
Metamorphic rock is rock that has changed from one form to another in response to changing environmental conditions around the rock. It does this until it reaches equilibrium with it"s surroundings. Metamorphism can change composition, size and shape of mineral grains as well as texture, density, and colour of the rock they are a part of. Every metamorphic rock has a parent rock (the protolith), being the rock type that was metamorphosed. These photoliths can be igneous rocks, sedimentary rocks, or other metamorphic rocks. The "grade of metamorphism" describes the temperature under which a metamorphic rock changed. Low grade being due to lower temperatures and high grade being due to higher temperatures. It is generally possible to identify the protolith of a low-grade metamorphic rock. And it is relatively impossible to identify the protolith of a high-grade metamorphic rock. The lower the grade, the more possible it is to identify the protolith.
