Here at the AZGS, we get many hundreds of inquiries - from homebuyers, exploration companies, news outlets, rockhounds, other government agencies, and people just curious about the geology and geography of the state.
I got an email the other day from someone who had flown over Arizona on their way from California to Texas who was amazed by Meteor Crater but puzzled by large circular holes in the ground to the east. He asked if we could explain what he had seen.
AZGS Senior Geologist Jon Spencer suspects he was looking at a cluster of sinkholes produced where evaporates dissolved from the Supai Formation, leading to collapse in the overlying Kaibab Limestone [right].
[update 5-3-10, 11:30] AZGS geologist Steve Rauzi weighed in this morning, saying that the photo shows the McCauley Sinks south of Winslow along the western edge of Permian salt in the Holbrook basin. He also pointed me to a paper by James Neal describing these features in some detail.
Ref: Neal, James T., Robert Colpitts, and Kenneth S. Johnson, 1998, "Evaporite Karst in the