Abstract

Floating streams of pumice covering an area of at least 2,000 square miles were encountered in the vicinity of the South Sandwich islands in the south Atlantic Ocean by the ice patrol vessel H.M.S. Protector on March 14, 1962. Nearby islands were not the source. As the sea currents have an easterly direction at about eight miles per day, the source is considered to have been a submarine eruption to the west. Calculations based on water content of pressure conditions indicate a possible depth of 1,100 fathoms or less. It is suggested that the eruptive center is an area of shallow water that lies north of the South Sandwich arc, and the record of an earthquake in that area on March 5, 1962, would seem to confirm this. Bottom samples collected subsequently have been found to be similar to the raft material. The pumice is a vesicular, gray, glassy material with crystals of plagioclase, magnetite, and pyroxene. Two small inclusions were found. The petrography of the pumice and the inclu

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