After building a snow bridge to disperse weight, a D7 Caterpillar safely pulls crew housing trailers on ski's over a crack in Beaufort Sea ice north of the coast of Alaska.   Next Alaska Stock Photos   Click Here for all Stock Photo Galleries   Model Released People Lifestyle Stock Photography & Other Topics. These Stock Photos are available for use license. arctic, snow, cold, north, seismic, research, oil, rig, rigs, beaufort, sea, ocean, alaska, vehicle, cat, caterpillar, tread, crack, bridge, trailer, housing, crew, geophysical, exploration, scientific, electronics