The Grand Canyon of the Yellowstone River is more than 1,000 feet deep in most places, up to 4,000 feet wide, and 20 miles long. It was carved from old rhyolitic lava flows and thermally altered by heat and gases from the Yellowstone Volcano. Far below, the Yellowstone River continues etching the canyon deeper and wider. From Grand View, Upper Falls and Lower Falls are hidden behind one or more bends in the canyon. Around 1900, Yellowstone visitor Mr. Reeves wrote that the Grand Canyon of the Yellowstone was the grandest, most sublime sight he had ever seen, with narrow, steep bridle paths high above the river and immense Painted Cliffs in soft shades of yellow, pink, light browns, and reds blending beautifully, with a few pines clinging to the sides.