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9.17: World Oceans and Landmasses During the Ice Ages

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    10296
    • Contributed by Miracosta Oceanography 101
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    World Oceans and Landmasses During the Ice Ages

    Sea level change since the end of the last glaciation has had major impacts on humans and all "remaining" species alike. A major mass extinction has been on-going since the last ice age. Many will argue that it is because of human over-consumption, but climate change and sea-level-rise have also been major contributing factors (the two factors are linked). When sea level was low, humans (and other species) were able to migrate throughout the world when what are today's continental shelves were coastal plains (Figure 9.35 and 9-36).

    Global topgraphy (bathymetry and topography) reveals the continental shelves that were exposed as coastal plains during the Pleistocene Epoch and early Holocene times bering land bridge
    Figure 9.35. Map of the world with continental shelves shown in light blue. During the peak of the last ice age continental shelves were exposed as extensive coastal plains (allowing humans to migrate). Figure 9.36. The continental shelf in the Bering Straits region between Siberia and Alaska was exposed during the last ice age, allowing many species (including humans) to migrate between continents.

    At the peak of the last ice age sea level about 400 feet (120 m) lower than today. What are now continental shelves were exposed land (coastal plains) that extended out to near the shelf break around continental landmasses. Rivers and streams carved canyons that have flooded as sea level rose, creating fjords, estuaries and bays we see around the world today. Most of the record of human prehistory is now submerged.