As part of the astronauts' training, USGS and NASA geoscientists gave lectures and field trips during the 1960s and early 1970s to teach astronauts the basics of terrestrial and lunar geology. Field trips included excursions into the Grand Canyon to demonstrate the development of geologic structure over time; Lowell Observatory (Flagstaff), Kitt Peak National Observatory (Tucson) and the Naval Observatory Flagstaff Station, NOFS (Flagstaff); Meteor Crater east of Flagstaff ; and Sunset Crater cinder cone and nearby lava flows in the Flagstaff area. This training was essential to giving astronauts the skills and understanding to make observations about what they would see on the lunar surface and to collect samples for later study back on Earth.