Another of my favorite mountains going down Highway 118 is Willow Mountain (3,380 feet), about 2-1/2 miles north of Study Butte, a reddish brown quartz trachyte mushroom-shaped intrusion, a trapdoor laccolith. The trapdoor opening is on the left of the photograph.
Its south face has one of the most spectacular displays of columnar jointing in the Big Bend. Jointing develops in intrusions and lava flows when they shrink as they cool. These columns are up to 400 feet long.
This mountain was purchased by my father, Paul Vonn, in the early ’70s. Before he died in the early ’90s, it became mine. I sold it in 2005 to a lawyer from Austin. I have more pictures taken from the frontal view.
Martha E. von Cotzhausen