Tongtaiqiao Arch is a natural bridge located on the northern hillside of Mount Yangyuanshan. It is 50 meters long, with a span of 38 meters, an arch height of 15 meters, and a bridge surface width of 6 to 8 meters, with the thinnest part of the bridge surface being only 3 meters thick. Its formation is related to the cracks within the rock, the erosion by flowing water, and the collapse under gravity. Originally, Tongtaiqiao was a single, intact rock body, but there were cracks (geologists refer to them as joints) within the rock. These cracks are weak zones in the rock, and water flowing through the rock will preferentially follow these cracks, quickly enlarging them into caves. Over time, weathering and collapse further expanded the caves, eventually connecting both sides of the rock and forming the stone arch.
