I dunno where else to put this but on Google Earth I found either one of two things:
A huge glitch
One of earth's greatest un-named, unknown natural wonders
First, in Google Earth, start in Ft Hancock, Texas, follow the Rio Grande/Rio Bravo river just along the border.
Wham! All of a sudden, deep, narrow ravine in the earth just outside of the town! Take that Grand Canyon, Angel Falls!
Closest town near the chasm is Mc Nary, Tx. You'd think searching "Mc Nary canyon" would come up with something, but nope!
Second closest city is El Provenir, Mexico. This screenshot shows one of the strange spikes in elevation that are along the chasm.
Also of note is the extreme farming along the chasm, Look at how that field just goes straight down!
The last screenshot is the most baffling of all! The chasm ends just as abruptly as it starts and the Rio goes right back up! At one of these ends is a reverse waterfall of some kind, or maybe the chasm is slowly filling up with water, who knows!
- The Great Rio Grande Chasm on Google Earth