The McDowell Mountains, 20 miles northeast of the Phoenix metro area, hosts one of Arizona’s largest landslides. About 500,000 years ago (Pleistocene), a portion of the east-central summit of the McDowell Mountains suddenly collapsed into a catastrophic rock avalanche.
The Marcus landslide originated in weathered granite bedrock at 1,334 meters (4,067 feet) above sea level -- near the second highest ridgeline in the McDowell Mountains; known locally as East End.
The landslide entrained nearly 5.5 million cubic meters (194.2 million cubic feet – or enough Earth material to fill six ASU Sun Devil Stadiums!) of loose granite bedrock and weathered granite (coarse sand-size particles known as grus). The estimated total weight was about 11.7 billion kilograms (25.8 billion pounds), equivalent to 1.5 times the weight of water in Tempe Town Lake!
