Roaring Mountain, Yellowstone National Park

This area of thermal activity covers the side of a mountain, thus the name. The description from the National Park website describes it thus: "Roaring Mountain, located 4.5 miles north of Norris Geyser Basin, is a barren, furrowed, white ridge, rising 400 feet from the base. The mountain side is spotted with steam vents or fumaroles, and the fumaroles' vents are rimed with bright yellow, crystalline sulfur deposits. The leaching of sulfuric acid has produced the stark, barren environment."