Now for a bit of a twist in this geological plot. Turning to botany for a second, look at the picture below of the fruit of Screwbean Mesquite. "Screw" in Spanish is "tornillo". This plant, found along many dry streams and other locations, has given its name to Tornillo Creek and Tornillo Flat in Big Bend. The trail to the pouroff is generally up a dry stream bed, and there are plenty of these bushes/small trees along the way.