Thursday: Tucson to Las Vegas arrow_back_ios_new Previous The fauna of the region. The flora of the region. Lunch stop at Burro Creek bridge. Thursday morning, 7 a.m. The Keystone Thrust Fault, part of the Las Vegas Shear Zone, pushed older limestones up over young, red sandstones. Zibi in the foreground for scale. Those wacky young-uns do the YMCA. Later in the trip, they impress everyone by spelling other four-letter words. arrow_forward_ios Next