For continuity of the ice cores this problem could easily be overcome by auguring adjacent to the thermal borehole using the SIPRE developed shallow (100m) mechanical drill. The ice below 70m was completely satisfactory for core studies. in 1962 the thermal drill was tested again at Camp Century and a new core obtained to a depth 246m. In 1963 another new hole was started and a third new core was augured to a depth of 264m, extended to the 535m depth in 1964 (Hansen, Ueda, Garfield).
Although the thermal coring method worked with satisfaction it was considered a slow method for very deep core drilling objectives. It was also realized that a thermal process would not penetrate the heavily laden solid particles and debris layers auticipated to exist near the base of the ice sheet. Consequently, Hansen had also been working on an alternative drilling method with a more rapid rate of penetration and a rock cutting capability, along with the development of the thermal drill system. The solution was found in an available reconditioned deep-rock auguring Electrodrill invented by A. Arutunoff, (Reda Pump Co.), Bartsville, Oklahoma. The Electrodrill was purchased, modified for drilling in ice, and transported to Camp Century in mid-1965. The Electrodrill, using a diamond cutting bit, was inserted in the 535m bore hole and rapidly cored from to 1002m before the 1965 season ended. On July 4th 1966 the Electrodrill reached the bottom of Greenland ice sheet at 1387m, and into 3.6m of sub-ice. The lowest 17m of the ice core contained silt bands, pebbles and some cobble sized fragments (Ueda and Garfield, 1969)
After the Camp Century operation the Electrodrill was air transported to Byrd Station and used to core to the 227m depth before the end of the field season in February 1967. Drilling was resumed at Bryd Station at the start of the next field season in November 1968, and reached the bottom of the Antarctic ice sheet at 2164m on January 1968 (Ueda and Garfield, 1969).
Another turning point in the SIPRE/CRREL ice sheet drilling program occurred shortly after the success of the Byrd Station project (SIPRE relocated an combined to become CRREL, Hanover, NH in 1961). A collaborative multidisciplinary core studies program had been developing since 1962 between SIPRE, the University of Bern (1962, H. Oeschger) and the University of Copenhagen (1966, Dansgaard). Each laboratory was pursuing and developing their own specialities and research interests in ice core science; SIPRE/CRREL; physical properties, chemical stratigraphy and mechanical behavior, in addition to its overall major emphasis on engineering development of shallow (100m), intermediate (400m), and deep (to bedrock) ice core drilling systems; University of Bern： 14C, 10Bc, 36Cl, geochemical modeling, air bubble gas composition, CO2 variability, and shallow drill development; University of Copenhagen; stable isotopes, dust content, climate variations, geophysical modeling and deep core drill development.
A major benefit of this collaboration was an obvious pooling of research expertise and established laboratory facilities, combined with the immediate exchange and knowledge of detailed results of tests, experiments and measurements from each others studies.
