It has been known for years that the Deccan Traps, an area of volcanic rock in central India, was an active volcano around 65 million years ago. It has even been suggested that it was massive volcanic eruptions from that region that killed the dinosaurs, rather than an asteroid impact. A new study indicates that environmental changes had already been causing mass extinctions on the ocean floor at the time the asteroid hit Mexico's Yucatán Peninsula.
A research team from the University of Washington examined sediment and fossils from Seymour Island, off the Antarctic Peninsula, using a method called magnetostratigraphy — comparing the magnetic polarity of the sediment to known changes in Earth's magnetic field over time. The unusually thick layers of sediment on Seymour Island gave the researchers better accuracy in their estimates of when the layers, and any fossils in the layers, were deposited.
"The eruptions started 300,000 to 200,000 years before the [asteroid] impact, and they mayRead More »from Dinosaur die-out may have been second of two close extinctions