Box canyon

The Box Canyon was adequately named. It was a box, a trap.

For days he camped on Wildfire's trail, always relentlessly driving him, always watching for the trap he hoped to find. . . . Sooner or later Wildfire would go down into a high-walled wash, from which there would be no outlet; or he would wander into a box-canyon.

Highway 145 dead-ends on the east end of Telluride, where a box canyon affords no further passage.