Mesozoic the Innuitian orogeny, the Brooks Range, the Verkhoyansk and Cherskiy Ranges in Siberia, and the Khingan Mountains in Manchuria. This orogeny was related to the opening of the Arctic Ocean and subduction of the North China and Siberian cratons under the Pacific Ocean. In contrast, the era featured the dramatic rifting of the supercontinent Pangaea, which gradually split into a northern continent, Laurasia, and a southern continent, Gondwana. This created the passive continental margin that characterizes most of the Atlantic coastline (such as along the U.S. East Coast) today. By the end of the era, the continents had rifted into
Middle Jurassic cycads, and ferns were also common. Middle Jurassic The Middle Jurassic is the second epoch of the Jurassic Period. It lasted from about 174 to 163 million years ago. Fossil-bearing rocks from the Middle Jurassic are relatively rare, but some important formations include the Forest Marble Formation in England, the Kilmaluag Formation in Scotland, the Daohugou Beds in China, Itat Formation in Russia, and the Isalo III Formation of western Madagascar. During the Middle Jurassic epoch, Pangaea began to separate into Laurasia and Gondwana, and the Atlantic Ocean formed. Tectonic activities are active on eastern Laurasia as the Cimmerian plate