During the Triassic period, there were no separate continents like there are today. Almost all the Earth's land mass was together in a single supercontinent called Pangaea ("all the land"). Pangaea was centered more or less on the equator. All the deep-ocean sediments (the things that settled at the bottom of the ocean) had disappeared. This happened because oceanic plates moved sideways and downward until they were finally on top of each other, or under each other.