Organ Mountains, New Mexico, USA
U.S. Bureau of Land Management photo (fair use policy)
The Organ Mountains mark a long block of intrusive rocks within the Rio Grande Rift. The chevron shape of the outcrops and strong vertical jointing in the intrusion make the range resemble the ranks of pipes in an old-fashioned church organ. On the other side of this range is White Sands National Monument.
The Rio Grande Rift is a place in the North American crustal plate where it cracked and started to open. It's similar to the East African Rift Valley, except that unlike the African rift it doesn't go all the way across the plate. This kind of stillborn rift is called an aulacogen (aw-LACK-o-jen). You can see it better in the New Mexico geologic map.
