 The average slope is 85.3 feet per mile (15.37 meters per kilometer).Beaver Creek's course is located in a region of diabase rock which intruded into the local sedimentary layers of the Brunswick and Lockatong Formations during the Jurassic and the Triassic, then the remaining course flows over the Brunswick Formation.Diabase is a dark gray to black, fine grained and very dense, consisting of primarily labradorite and augite.