Here's why:
* Depth and Pressure: At 20 kilometers, the immense pressure and heat from the Earth's interior transform existing rocks (igneous or sedimentary) into metamorphic rocks.
* Metamorphic Processes: The intense heat and pressure cause changes in the mineral composition, texture, and structure of the original rocks. This process is called metamorphism.
* Examples of Metamorphic Rocks: Examples of metamorphic rocks formed at such depths include:
* Gneiss: A high-grade metamorphic rock formed from granite or other igneous rocks.
* Schist: A medium-grade metamorphic rock with a foliated texture (layered appearance).
* Marble: A metamorphic rock formed from limestone.
Note: While igneous rocks are formed from molten magma, they are primarily found near the surface or within the Earth's crust. While sedimentary rocks are formed from sediments that accumulate on the surface, they can be buried and transformed into metamorphic rocks at greater depths.
