The largest explosions, which were set off on top to test the strength of the sandstone tunnels, were advertised in the newspapers as to the date and time. Many residents of Emery Country drove out to the area and witnessed the TNT explosions. These photographs were taken by individuals who were present on that day. They could not get close to the area, but could drive to certain vantage points. This explosion collapsed the top of the largest tunnel. The sandstone failed and the Department of Defense withdrew the project. Craters and tunnels were abandoned, leaving local residents to speculate as to the reasons for the experiments. Most people think it was to see if the rock could withstand a nuclear blast so they might built the North American Aerospace Defense Center or NORAD which was built in the granite mountain near Colorado Springs in Colorado.