The 42-acre Alluvial Fan was created on July 15, 1982, at 5:30 am when Lawn Lake broke through the terminal moraine that had held since the end of the last ice age. The release of 29 million gallons of water swept trees, car-sized boulders, lighter rocks, gravel, and sand 4 miles down the valley floor. Although much of the flood's force was absorbed in the meadows of the valley, the water continued on to flood Estes Park to a depth of 6 feet.
