Big Bend: Burro Mesa Pour-off Trail

The short, hot walk up the Burro Mesa Pour-off Trail is a stroll through the volcanic history of Big Bend, much of it laid out in the tall bluff to the left as you enter the canyon.

The dark basalt and conglomerate at the bottom of bluff – much of which is buried in eroded sediment – is the same volcanic rock that lies under the Chisos Mountains to the east.

About 30 million years ago, new volcanic flows poured over the top of those Chisos rocks from nearby vents, producing the dark Burro Mesa rhyolite at the top of the bluff and the light yellow wedge of the Wasp Spring breccia immediately below it. It was the last significant volcanic activity in Big Bend. The entire lineup is a mirror of the rocks along the South Rim, only dropped several thousand feet here by subsequent faulting.

The trail climbs slightly through the desert before dipping into the sandy wash that leads into the canyon. From there, it veers into the box canyon to the right, following a rocky wash strewn with with Texas persimmon. It snakes around to the left, where the pour-off looms ahead.