Geomagnetism research. US geologists Allan Verne Cox (seated, 1926-1987), Richard Doell (centre, 1923-2008), and (Gary) Brent Dalrymple (right, born 1937) at a control panel for geomagnetic experiments. All three worked in the 1960s on geomagnetic reversals, developing the timescales allowing magnetic changes in rocks to be used for geological dating. Cox and Doell received shares of the 1970 Vetlesen Prize for this work. Photographed circa 1965 at the US Geological Survey, Rock Magnetics Laboratory, Menlo Park, California, USA. This photograph is part of the Historic American Engineering Record (HAER).