Gilbert and Ellice Islands the latitude of 5° to 10° south and longitude of 176° to 180°, west of the International Date Line. The Ellice Islands are midway between Hawaii and Australia. The Ellice Islands are recognised as part of the Polynesia subregion of Oceania. In 1606 Pedro Fernandes de Queirós sighted Butaritari and Makin, which he named the Buen Viaje (‘good trip’ in Spanish) Islands. The Gilbert Islands were named in 1820 by a Russian Admiral, Baron Johann von Krusenstern, after a British captain, Thomas Gilbert, who encountered the archipelago in 1788 while exploring an Outer Passage route from Port Jackson to Canton.
Geology of the Pacific Ocean . The Pacific Ocean developed from the Panthalassa, a vast global ocean, following the breakup of the supercontinent Pangaea in the Mesozoic Era, gradually forming Gondwana and Laurasia, which in turn divided. There is no firm date for when the changeover occurred, as the replacement of the sea bed is a continuous process, though reconstruction maps often change the name from Panthalassic to Pacific around the time the Atlantic Ocean began to open. The Panthalassic Ocean first opened around 750 million years ago at the breakup of Rodinia, but the oldest Pacific Ocean floor is only around 180 Ma old.