This metal plaque is found near the viewing area to the west of Hog's Back Falls, on the side of the stairs leading up to the weir walkway. The plaque states, "THESE ROCKS, SANDSTONES AND LIMESTONES, WERE FORMED ON THE BOTTOM OF A SHALLOW SEA WHICH COVERED THIS REGION IN ORDOVICIAN TIMES SOME 400 MILLION YEARS AGO. NOTE THE RIPPLE MARKS FORMED BY THE ANCIENT WAVES. LATER THE REGION WAS UPLIFED AND THE STRATA HERE WERE FOLDED AND BROKEN. A MAJOR BREAK OR FAULT CAN BE SEEN AT LOW WATER JUST BELOW THE EAST END OF THE BRIDGE. THE PRESENT COURSE OF THE RIVER OVER THESE ROCKS WAS ESTABLISHED AT A STILL MUCH LATER DATE."