Abstract

A suite of shore lines and horizontal coralliferous limestone terraces of Quaternary age, indicating halts of the sea 560, 260, 215, 150, 100, 45, 27, and 5 feet above mean sea level, and drowned valleys and shelves indicating halts at about 60 and 300 feet below sea level are present on Espiritu Santo Island in the New Hebrides group. Other terraces at intermediate levels above 45 feet were seen, but their altitudes were not determined. Remnants of a terrace about 1200 feet above sea level are also present. The terraces correspond in altitude and in sequence with those on the Hawaiian Islands about 3000 miles away, which seems to indicate that eustatic shifts in sea level ranging from at least 300 feet below to 560 feet above present sea level may have occurred in Quaternary time. Several of the terraces have been identified on Saipan in the Marianas Islands 3200 miles west of the Hawaiian Islands and 2229 miles north of Espiritu Santo Island. Four hypotheses are offered to account for the great shifts in sea level. It is believed that these eustatic shifts gave opportunity for the great development of coral reefs in the Pacific in Pleistocene time. The smaller shifts appear to be chiefly the result of the rise and fall of sea level concomitant with glaciation and deglaciation and concurrent changes in the configuration of the ocean floors.

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