The easternmost part of California's Trinity Alps are informally known as the Red Trinity Alps. The appellation is a result of the abundance of peridotite and red serpentine. Peridotite is a rock the occurs in abundance only in the Klamath Mountains (of which the Trinity Alps are a part) and in the Brooks Range in Alaska. The rugged, bright red mountains in this region are striking and unusual. While the red stone is certainly dominant in this area, there are still significant intrusions of granite and sedimentary rocks, as well as a small amount of sandstone. This cacophony of stone types adds to the visual interest of the area, creating a unique alpine setting. The Trinity Alps are one of California's most spectacular mountain ranges, yet it remains fairly anonymous and lightly visited.