Geosite List Home Geosite The Hashigui-iwa Rocks The Hashigui-iwa Rocks Rock towers line up for as long as 900 meters in a straight line that looks like a bridge pile. The magma that flowed from underground about 14 to 15 million years ago had penetrated the Kumano strata to make a quartz porphyry dike. Map The Hashigui-iwa Rocks 33.4875808,135.7955968,14 See in the map app