3 résultats pour "oceanography"
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Ocean and Oceanography.
of sediment. When studied in sedimentary core samples, which can represent many millions of years of deposits, they provide a detailed and continuous history of theearth’s environmental changes. The record is particularly informative for the most recent 2 million to 5 million years, during which major fluctuations in global climatehave occurred. Successive ice ages can be traced by the relative scarcity or abundance of the shells of warm-water and cold-water diatoms in various layers of asedimen...
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Ocean and Oceanography - geography.
gravity, so the level of the ocean will be lower over valleys. Using this method, a complete survey of the ocean floor was accomplished in less than two years. Maps madefrom data on the level of the ocean surface have been compared with maps made with direct depth measurements and the two types have corresponded well. Using sonar, depth measurements are made by measuring the time for a sound wave to travel from the surface of the ocean to the ocean floor, and to return ( see Sounding). Often sev...
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Ocean and Oceanography - Geography.
of sediment. When studied in sedimentary core samples, which can represent many millions of years of deposits, they provide a detailed and continuous history of theearth’s environmental changes. The record is particularly informative for the most recent 2 million to 5 million years, during which major fluctuations in global climatehave occurred. Successive ice ages can be traced by the relative scarcity or abundance of the shells of warm-water and cold-water diatoms in various layers of asedimen...