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Geohistory

Alligators used to live on what was once Oki?

In the early summer of 2008, a university student who visited Oki in order to conduct a geological survey discovered a fossilized alligator tooth from a 20 million-year-old geological layer. Fossils of pond snails and freshwater bivalves had already been discovered in the same location, but this was the first time for an alligator tooth to be found there.

“Alligators used to live on Oki.” What this means is that in primeval times, there had to have been a lake environment, the sort where alligators would have been able to live. But if you think about this for a moment or two, you start to realize how strange this is. Oki is a group of islands that are in the Sea of Japan, and are of a geographical structure much different from that of lakes.

However, it is this very situation that hides the secret behind the formation of the Japanese Archipelago and the Sea of Japan. Exactly how did the Oki Islands form? Let us explain.

  1. 250 million years ago - 26 million years ago

    The Continental Age

    Oki 50 million years ago

    Oki used to be part of the Asian continent

    More Info

  2. 26 million years ago - 10 million years ago

    Formation of the Sea of Japan

    Oki 23 million years ago

    From a paradise where alligators lived, to the bottom of the sea

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  3. 10 million years ago - 5 million years ago

    Volcanic Island Era

    Oki 5.5 million years ago

    Violent volcanic eruptions lead to the birth of Oki

    More Info

  4. 400 thousand years ago - Now

    From Peninsula to Islands

    Oki 20 thousand years ago

    Separation from the mainland to the current form of the Oki Islands

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