Hole-in-the-Rock
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. This is a great place to watch the sun set over Phoenix.
geologicalhero
