Here's a breakdown:
* Metamorphic rock: Formed when existing rocks (in this case, sandstone) are transformed by heat, pressure, or chemical reactions.
* Metagraywacke: A metamorphic rock formed from the transformation of graywacke, which is a type of sandstone with a high content of rock fragments.
The original sandstone that Pilot Mountain is formed from dates back to the Precambrian Era (over 540 million years ago). The intense heat and pressure that transformed the sandstone into metagraywacke occurred during the Appalachian Orogeny, a period of mountain building that occurred over hundreds of millions of years.
