The Marcus Landslide formed as a result of partial flank collapse along the east flank of the McDowell Mountains in Maricopa County. In 2018, Steve Skotnicki released a 1:12,000 scale geologic map detailing the complex geology of the McDowell Mountains and environs.
That map, which include two dozen photos, including this one, can be downloaded at https://library.azgs.arizona.edu/item/AGCM-1552429194087-328
Photographer: Brian Gootee
Photo Date: circa 2016