Near the end of my rafting trip down the Colorado River through the Grand Canyon, we start to witness a rock layer not familiar to the vast majority of visitors to the Grand Canyon, and in fact, most people are surprised to find out that such rocks are present in the national park: There are volcanoes and lava flows here! In this part of the river, black basalt clings to cliffs from high up, all the way down to the water, and in one area shows a full trail of its flow all the way down from the top of the canyon. Up there the remains of a ancient cinder cone called “Vulcan’s Throne” rests, and from it a long tongue of old lava flow from the throne can be seen all the way down to the water. It was clear we were soon about to experience Lava Falls, the final and one of the most famous rapids on the river.