Question

Metamorphic rocks indicate that ______

1) an even older parent rock once existed in that place
2) igneous rocks formed in the same place
3) the rock composition has not changed over time
4) the rock was formed through volcanic activity

Answer 1

Metamorphic rocks signify that an even older parent rock, also known as the protolith, existed and was transformed by heat and pressure into the metamorphic rock we observe today.

Step-by-step explanation:

Metamorphic rocks are a profound showcase of Earth's dynamic processes, providing clear evidence that an even older parent rock once existed in the same location. These rocks emerge from the transformation of pre-existing igneous, sedimentary, or even older metamorphic rocks that are subjected to new conditions of heat and pressure. The process is known as metamorphism, which literally means to change form, leading to the recrystallization of minerals in the rock without the rock melting. This alteration creates new mineral assemblages and textures that are stable under the pressure and temperature conditions to which the rock is exposed. Therefore, metamorphic rocks are indicative of the rock cycle at work, showcasing the ongoing recycling and alteration of materials that compose Earth's crust.