The breakup of Pangaea did not happen all at once. There were four stages. In the late Triassic Period Laurasia and Gondwanaland began rifting. By the early Jurassic the expanding Atlantic Ocean had separated North America and Africa. During the second phase, Antarctica seperated from Gondwanaland. India moved toward the equator. The third stage happened in the late Jurassic Period. South America and Africa split. The Tethys Sea begins to close and Laurasia moves clockwise and Africa moves north. The final phase, Greenland separates from Europe and North America to form its own landmass occured during the Cenozoic Period.

During the early and middle Triassic Periods, in the area from Nova Scotia to North Carolina, fault block basins formed as magma swelled under the land's surface. Erosiion of mountains filled in the basins with poorly sorted sediments. This area is called the Newark Group. At the same time lava flowscovered the basin floors. Several sills and dikes were created. One of the most noticeable is the Palisades Sill which follows along the Hudson River in the New York, New Jersey area. It was formed almost 200 million years ago.