Chaos Jumbles, a massive debris avalanche from a series of dacite domes (Chaos Crags) north of Lassen Peak, Lassen Volcanic National Park, California. The domes formed by extrusion of viscous magma, and tend to be very steep. Eventually they collapse, forming debris avalanches. These avalanches occurred around 1600 A.D. The Park Service wisely moved a visitor center and campground from this area.