| Summary: | Seismic reflections obtained from bedrock beneath the Malaspina Glacier along a tenâ€mile profile line indicate ice thicknesses ranging from 1130 to 2050 ft. The base of the ice is 700 ft below sea level near the center of the profile and shallows both northward toward the mountains and southward toward the ice margin. Good reflections were obtained with dynamite charges of about one ounce in 26â€ft waterâ€filled shot holes but only in relatively crevasseâ€free areas. Deeper reflections substantiate the inferred sedimentary nature of the subglacial rocks and show geologic structures consistent with the regional pattern. Gravity measurements along the central three miles of the seismic profile line indicate a gentle northwestâ€southeast trending subglacial topographic grain. Seismic refraction shots beyond the present margin of the glacier suggest a thickness of unconsolidated proglacial deposits in excess of 500 ft. © 1953 American Geophysical Union. Communicated manuscript received December 29, 1952; open for formal discussion until March 1, 1954. The field work was done under the supervision of R. P. Sharp and the office work under C. H. Dix; both have criticized the manuscript and their guidance i s gratefully acknowledged, D. L. Baker and G. P. Rigsby took considerable time from their own field projects to aid in the geophysical work. Valuable equipment was loaned by the United Geophysical Co. and the Atlas Exploration Co. The work was done under the sponsorship of the Office of Naval Research (Contract N6onr-244-16), the Arctic Institute of North America, and the California Institute of Technology. Published - Allen_et_al-1953-Eos_2C_Transactions_American_Geophysical_Union.pdf
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