This image was acquired from
wikimedia. It was marked as Public Domain or CC0 and is free to use. To verify, go to the source and check the information there.
Keywords from Image Description:
SourlandTraprock. argillite and argillite derived hornfels emerges along the ft contour of located near Hillsborough Township New Jersey Typical argillite in this region is grayish color while hornfels appears blackish and more fine grained due to the effects of contact metamorphism selfphotographed original text Photo taken by