The outcrop is fenced off but Dickas states that it can be seen from the overpass.  The Catoctin greenstone represents 700 million year old basalt flows (interspersed with sandstones) that poured out during rifting of the continent of Rodina.  The rocks were later metamorphosed when Africa and North America collided.  The rocks now form a boudinage extenstional structure (sausage shaped) of sandstone and greenstone.  Greenstone consists primarily of chlorite with some epidote giving it a green color.