Metamorphism of Shale and Sandstone in the Black Hills

Detailed Description
The bedrock of the Black Hills contained shale and sandstone which were metamorphosed into schist and sandstone, respectively.
Sources/Usage
Public Domain.
https://ohiodnr.gov/discover-and-learn/rock-minerals-fossils/common-roc…;
https://www.nps.gov/articles/should-i-replace-my-slate-roof-with-a-synt…;
https://maps.dggs.alaska.gov/photodb/detail/11210
https://www.usgs.gov/media/images/schist
https://ohiodnr.gov/discover-and-learn/rock-minerals-fossils/common-rocks/sandstone
https://www.dhr.virginia.gov/projectiles-lithics/nottoway-river-quartzi…;