The Blackhawk Landslide, San Bernardino mountains, California
The largest slide in the Transverse Range province is the Blackhawk, on the north slope of the San Bernardino Mountains, California. This prehistoric slide is one of the largest known in North America. It was studied in detail by R. L. Shreve in the 1950's and 60's, who introduced the hypothesis that long-runout landslides may move on a cushion of compressed air. However, landslides on Mars and icy satellites occur even without any air to ride on, and other hypotheses have been considered since Shreve's original work.
Here is an aerial view:
Aerial view of the Blackhawk Landslide, in California
The Blackhawk slide is 8 kilometers long, about 3 kilometers wide wide, and 10-30 meters thick. It is a tongue-like sheet of brecciated Pennsylvanian Furnace Limestone derived from Blackhawk mountain about 1200 meters above.