Hundreds of thousands of years ago the massive Mount Tehama volcano dominated what is now the southern side of Lassen Peak in Lassen Volcanic National Park. The collapse of its large 2-mile wide caldera has since left a series of smaller landforms as well as the Sulphur Works, the volcanic center of what used to be Mount Tehama that is still very active to this day.
The Lassen Volcanic scenic drive (CA-89) actually goes over part of the Sulphur Works and has paved sidewalks on both sides that eventually lead to a paved parking area with a restroom off the road. On the south side of the road is a steam vent, and on the north side is a boiling mud pit as well as a view up the hill where the terrain is colored with bright whites, yellows, and oranges due to the sulfuric gases and acids breaking down the terrain. All in all, the Sulphur Works are a much smaller and more accessible version of the larger and more popular Bumpass Hell geothermal area, the trailhead of which is just a few miles up the road for those entering from the south.