This is the Rio Grande Rift just west of Taos, New Mexico. This is not a canyon formed by the Rio Grande; it is a region where the crust of the earth has spread apart, and the river has adopted it as its path. The rift was initially formed about 30 million years ago, and is similar to rifts found in the center of the Atlantic and Pacific oceans; there are only two others on land. Today the rift continues to slowly widen.
I took this picture from the West Rim mountain bike trail within two miles of the Gorge Bridge where US highway 64 crosses over the rift. The trail is maintained by the U.S. Bureau of Land Management as natural wildlife habitat. See the Google Maps location of this image.
For a view further South in this rift, please see my other image:
The haze in the sky (which I think really adds to the depth of this image- particularly when viewed full-size) is from distant summertime forest fires in Los Alamos (70 miles away).
Canon 5D MK II, Tamron 28-300 VC, 3 images AEB +/-2, tripod mount, processed in aperture and the photomatix plugin