Must see on trip to New Mexico. http://hubpages.com/travel/State-Park-in-Texas-Palo-Duro-Canyon-Dramatic-Attraction http://tpwd.texas.gov/state-parks/palo-duro-canyon
Palo Duro Canyon, Canyon TX Cave exploration
15 great hiking trails in Texas. I would add Caprock Canyons of course :)
The Palo Duro Canyon, or "hard wood" in Spanish due to the abundance of juniper trees in the area, has been open to the public for over a century.