Geological history of Earth with highly seasonal rainfall patterns. Deserts seem to have been widespread on Pangaea. The Mesozoic extended roughly from . After the vigorous convergent plate mountain-building of the late Paleozoic, Mesozoic tectonic deformation was comparatively mild. Nevertheless, the era featured the dramatic rifting of the supercontinent Pangaea. Pangaea 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. The Triassic Period extends from about 252.17 ± 0.06 to 201.3 ± 0.2 Ma. During the Triassic, almost all the
Laurasia including West Virginia, Britain, and Germany. Siberia moved southwards and joined with Kazakhstania, a small continental region believed today to have been created during the Silurian by extensive volcanism. When these two continents joined together, Laurasia was nearly reformed, and by the beginning of the Triassic, the East China craton had rejoined the redeveloping Laurasia as it collided with Gondwana to form Pangaea. North China became, as it drifted southwards from near-Arctic latitudes, the last continent to join with Pangaea. Around 200 million years ago, Pangaea started to break up. Between eastern North America and northwest Africa, a new ocean