The "Holey Tour" planetary geology field trip, Arizona

Arizona has a wide variety of geological features relevant to planetary geology. The "Holey Tour" is a 2 d field trip (Phoenix-Flagstaff-Phoenix) that introduces participants to crater forms (hence the "holes" of the tour), including a maar, karst sinkhole, pit crater, cinder-cone craters, a volcano-tectonic depression, and the classic impact structure Meteor Crater. The Apollo astronaut field training site near Flagstaff is examined, which includes a terrain that was artificially generated to simulate a cratered lunar surface. In addition, planetary volcanism is discussed with stops that include a shield volcano, composite cone, silicic dome, and cinder cones; considerations include key variables in volcanic morphology, such as lava composition and rates of effusion. The general geology of Arizona is discussed throughout the trip and includes parts of the Colorado Plateau, the Basin and Range Province, and the Central Highlands (also called the "transition" zone). The trip can be adapted to meet the needs of any group, from secondary school students to established planetary scientists.