One of the largest known mass wasting events in North America is the Blackhawk slide in California’s Mojave Desert. Located in the Lucerne Valley area, north of the San Bernardino Range, the slide is ~5 miles long, ~2 miles wide, and between 30 and 100 feet thick. These extraordinary dimensions are attributed to almost frictionless sliding of the rock debris as it rode along a layer of compressed air, like a hovercraft or air-hockey puck. As the high pressure air squeezed out, the free ride ended, and the slide debris settled to the floor of the desert, somewhere in the neighborhood of 17,000 years ago.
A nice deposit of information on the slide can be found here:
Flash Earth link to the spot: