Geophysical evidence of shallow nearshore permafrost, Prudhoe Bay, Alaska

Marine seismic refraction data taken in and near Prudhoe Bay, Alaska, are presented. The higher compressional sound wave velocity in ice‐bonded materials as compared to unbonded materials was used to locate areas of subsea permafrost and depths to the top of the permafrost. These data are compared favorably with similar information from available drilling data. A map is presented which shows the extent of permafrost within 40 m of the ocean surface along approximately 40 km of the Beaufort Sea coast. The permafrost surface is shown to vary irregularly in depth without regard to the distance from shore. Large areas without shallow permafrost are attributed to possible paleo‐river‐valleys and to the lack of clays which may have been removed in these valleys.