A sinkhole in the Kaibab Limestone east of Flagstaff was once referred to as the 'Bottomless Pit'. Early in the 20th century a plug must have existed in the sinkhole allowing a lake to form. One day the plug failed and the lake waters disappeared into the sinkhole. The sinkhole is now fenced off to prevent access by the public.
This photo appeared in Darton & others, 1916, Guidebook of the Western United States: Part C - The Santa Fe Route, with a side trip to Grand Canyon of the Colorado.
Karst features, such as sinkholes and bedrock fractures are common in northern Arizona.
Online resources:
Darton and others, 1916, Guidebook of the Western United States: Part C - The Santa Fe Route, with a side trip to Grand Canyon of the Colorado. (USGS Bulletin 613) https://pubs.usgs.gov/bul/0613/report.pdf
Harris, R.C., 2002, A review and bibliography of Karst Features of the Colorado Plateau, Arizona. Arizona Geological Survey Open File Report, OFR-02-07, 43 p. https://library.azgs.arizona.edu/item/AOFR-1552427421088-565
Photographer: US Geological Survey
Photo Date: circa 1915
Photo Location Accuracy: Approximately Located