DEEP CORE DRILLING IN THE ROSS ICE SHELF, LITTLE AMERICA V, ANTARCTICA.

Abstract : Drilling operations and core and drill hole investigations at Little America V in Oct. - Dec. 1958, as well as measurements at Byrd Station in Dec. 1958 are discussed. The hole at Little America V reached 836 ft, and core recovery was 98% of the footage drilled. No saline ice was found in the bottom core, indicating that the bottom ice is melting. In detailed stratigraphic studies made to a depth of 53 m, summer snow deposits were coarse-grained and often associated with icy crusts, ice layers, and glands. Winter deposits were finer-grained, more homogeneous, and lacked the soaked appearance of summer snow. Periods of 2-3 consecutive years at more or less regular intervals of 10-20 yr showed intense ice formation. Layers of foreign material, tentatively identified as volcanic ash, were observed at 172.1 m, 219.4 m, and 222.8 m. The depth-density curve steepened between 20.7 and 36.5 m. If annual precipitation is estimated as 21 cm of water, Little America V rests on about 1225 yr of accumulated snow. Data (some of a preliminary nature) are tabulated and graphed: the depth-density profile to a depth of 53 m, the nature of ice at various depths, spot densities below 53 m, and the annual increments at depth and corresponding water equivalents at Little America V; ice temperature at various depths at both stations; and depth-inclination measurements as well as the diam-vs-depth curve at Byrd Station. (Author)