In 1892, Charles Poston named and claimed "Hole-in-the-Rock".^[1]

Hole-in-the-Rock is a series of openings (tafoni) eroded in a small hill composed of bare red arkosic conglomeritic sandstone. The sandstone was first formed some 6–15 million years ago from the accumulation of materials eroding from a Precambrian granite, long since eroded away. The tafoni are thought to have been eroded by water. An open, shelter-like chamber in the face of the formation communicates with the rear of the formation via a hole eroded completely through the rock. Another substantial opening exists in the "ceiling" of the chamber.

There is evidence that the Hohokam, early inhabitants of the region,^[2] used and recorded the position of sunlight shining through the latter opening to mark the seasons—notably the equinoxes and the solstices, which were marked by carving a slick area (metate) in the rock. Other positions were marked with boulders.

The formation is a popular attraction in the park. The openings and main chamber near the summit are easily accessible via a smoothly ascending path that passes behind the hill. It is also possible to climb the face of the hill to reach the chamber. While popular, the trail can be dangerous.^[3] The chamber provides a good view of the city of Phoenix west of the park.^[4] A nearly constant wind blows through the openings in the rock.

• List of historic properties in Phoenix, Arizona

• Papago Park Facts – provided by the City of Phoenix
• Hole-in-the-Rock – provided by Gemland

33°27′23″N 111°56′44″W / 33.4565°N 111.9455°W / 33.4565; -111.9455