Final answer:
Metamorphic rock is formed when other types of rocks are subject to high temperature and pressure, leading to physical and chemical alterations. The original rock is called the protolith, and common examples of metamorphic rocks include schist and marble.
Step-by-step explanation:
Rock that is formed from other rock under typical surface conditions is called metamorphic rock. This process occurs when pre-existing rocks, either igneous or sedimentary, are altered by conditions like high temperature and pressure.
The transformation can lead to a new texture or mineral composition, with features such as foliation or recrystallization. Metamorphic rocks come to exist because of geological activities that carry rocks to great depths where they undergo these changes, before possibly being brought back up to the surface.
The original rock from which a metamorphic rock is formed is known as the protolith or the parent rock. Common examples of metamorphic rocks include schist, slate, and marble, all of which have at least one parent rock that has been subjected to metamorphic processes. Key factors influencing metamorphosis include the geothermal gradient and tectonic pressures, typically found in mountain-building regions.