The Mesozoic Era began about 240 million years ago and ended about 66 million years ago. The era is best known as the age of the dinosaurs. It was an active geological era as well. At the beginning of the Mesozoic, there was one continent, Pangaea, and one ocean, Panthalassa. By about 180 million years ago, Pangaea began to break apart. At the same time, the Panthalassa Ocean began to separate into the individual but interconnected oceans that we see on Earth today. Why would a supercontinent break up after being together for tens of millions of years? A supercontinent is like a giant... Show more The Mesozoic Era began about 240 million years ago and ended about 66 million years ago. The era is best known as the age of the dinosaurs. It was an active geological era as well. At the beginning of the Mesozoic, there was one continent, Pangaea, and one ocean, Panthalassa. By about 180 million years ago, Pangaea began to break apart. At the same time, the Panthalassa Ocean began to separate into the individual but interconnected oceans that we see on Earth today. Why would a supercontinent break up after being together for tens of millions of years? A supercontinent is like a giant insulating blanket that does not allow mantle heat to escape very effectively. As heat builds up beneath a supercontinent, continental rifting begins. Basaltic lavas fill in the rifts and eventually lead to seafloor spreading and the formation of new ocean basins. The Atlantic Ocean basin formed as Pangaea split apart and seafloor spreading pushed Africa and South America apart. As the continents making up Pangaea moved apart, there was an intense period of plate tectonic activity. Seafloor spreading was so vigorous that the mid-ocean ridge buoyed upward and displaced so much water that there was a marine transgression. Much of the North American continent was covered with water. Later in the Mesozoic, those seas regressed and then transgressed again. The moving continents also collided with island arcs and microcontinents so that mountain ranges accreted onto the continents’ edges. For example, the subduction of the oceanic Farallon plate beneath western North America during the late Jurassic and early Cretaceous produced igneous intrusions and other structures. The intrusions have since been uplifted to form the Sierra Nevada Mountains. Show less
The Mesozoic Era began about 240 million years ago and ended about 66 million years ago. The era is best known as the age of the dinosaurs. It was an active geological era as well. At the beginning of the Mesozoic, there was one continent, Pangaea, and one ocean, Panthalassa. By about 180 million years ago, Pangaea began to break apart. At the same time, the Panthalassa Ocean began to separate into the individual but interconnected oceans that we see on Earth today. Why would a supercontinent break up after being together for tens of millions of years? A supercontinent is like a giant insulating blanket that does not allow mantle heat to escape very effectively. As heat builds up beneath a supercontinent, continental rifting begins. Basaltic lavas fill in the rifts and eventually lead to seafloor spreading and the formation of new ocean basins. The Atlantic Ocean basin formed as Pangaea split apart and seafloor spreading pushed Africa and South America apart. As the continents making up Pangaea moved apart, there was an intense period of plate tectonic activity. Seafloor spreading was so vigorous that the mid-ocean ridge buoyed upward and displaced so much water that there was a marine transgression. Much of the North American continent was covered with water. Later in the Mesozoic, those seas regressed and then transgressed again. The moving continents also collided with island arcs and microcontinents so that mountain ranges accreted onto the continents’ edges. For example, the subduction of the oceanic Farallon plate beneath western North America during the late Jurassic and early Cretaceous produced igneous intrusions and other structures. The intrusions have since been uplifted to form the Sierra Nevada Mountains.
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