Astronaut training included four months of studies covering subjects such as astronomy, orbital mechanics and spacecraft systems. Some 30 hours of briefings were conducted on the Apollo command and service module, and twelve on the Apollo lunar module. An important feature was training in geology, so that astronauts on the Moon would know what rocks to look out for. This training in geology included field trips to the Grand Canyon and the Meteor Crater in Arizona, Philmont Scout Ranch in New Mexico, Horse Lava Tube System in Bend, Oregon, and the ash flow in the Marathon Uplift in Texas, and other locations, including Alaska and Hawaii. There was also jungle survival training in Panama, and desert survival training around Reno, Nevada. Water survival training was conducted at Naval Air Station Pensacola using the Dilbert Dunker.