Red Mountain Trail No. 159 - Red Mountain Is A Volcanic Cinder Cone That Rises 1,000 Feet Above The Surrounding Landscape. It Is Unusual In Having The Shape Of A "U," And In Lacking The Symmetrical Shape Of Most Cinder Cones. In Addition, A Large Natural Amphitheater Cuts Into The Cone's Northeast Flank. Erosional Pillars Called "hoodoos" Decorate The Amphitheater, And Many Dark Mineral Crystals Erode Out Of Its Walls. Studies By U.S. Geological Survey (USGS) And Northern Arizona University Scientists Suggest That Red Mountain Formed In Eruptions About 740,000 Years Ago. The Trailhead Is Located On U.S. Highway 180, 25 Miles Northwest Of Flagstaff, Arizona. The Trail Is An Easy 1.5 Miles Through Open Terrain With Fantastic Views Of The San Francisco Peaks And Surrounding San Francisco Volcanic Field. There Is A Short (approximately 6 Feet) Ladder Climb Required Just Before Entering The Natural Amphitheater Of The Cinder Cone. Photo By Deborah Lee Soltesz, February 2015. Credit: U.S. Forest Service, Coconino National Forest. For More Information About This Trail, See The Red Mountain Trail #159 Trail Description On The Coconino National Forest Website. Photo