In the years 1920 to 1940 there existed in the United States a vast frontier of undeveloped area to challenge geophysics. A great unexplored reserve of oil traps awaited the enterprising geophysicists who first brought their scientific devices to these strange lands. Through those early years, there was always new acreage for everybody interested; it was only necessary to stay away from, or keep ahead of, the competition. It was a lush period of easy, ready exploration. The geophysical frontier was the virgin area.