The supercontinent Pangea as it was 200 million years ago, with black areas representing the extent of a magma flood that lasted several million years. Hundreds of basalt outcroppings rimming the Atlantic Ocean are actually the remnants of a single huge volcanic eruption that may have triggered mass extinction some 200 million years ago, according to a study led by a Berkeley researcher. The research team, headed by Paul R. Renne, director of the Berkeley Geochronology Center and adjunct associate professor of geology and geophysics, concluded that the basalt dikes, sills and lavas resulted from the most extensive pulse of magma eruptions known to date. Sills are what remain after magma intrudes into horizontal underground fissures, then cools and is subsequently exposed.
Dikes are the remnants of magma that flowed into vertical fractures.
Lava is magma that broke through the Earth's crust and flowed on the surface before cooling. Remnants of the eruptions are dispersed from the New Jersey Palisades and the Brazilian Amazon to Spain and West Africa. At the time these areas were near one another in the center of a supercontinent known as Pangea. The eruptions began a process that drove the land mass apart to create the Atlantic Ocean. The time of the eruptions matches within 20,000 years a global extinction at the end of the Triassic period and the beginning of the Jurassic.