<P> Compared to the vigorous convergent plate mountain - building of the late Paleozoic, Mesozoic tectonic deformation was comparatively mild . The sole major Mesozoic orogeny occurred in what is now the Arctic, creating 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 . 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 . </P> <P> By the end of the era, the continents had rifted into nearly their present form . Laurasia became North America and Eurasia, while Gondwana split into South America, Africa, Australia, Antarctica and the Indian subcontinent, which collided with the Asian plate during the Cenozoic, the impact giving rise to the Himalayas . </P> <P> The Triassic was generally dry, a trend that began in the late Carboniferous, and highly seasonal, especially in the interior of Pangaea . Low sea levels may have also exacerbated temperature extremes . With its high specific heat capacity, water acts as a temperature - stabilizing heat reservoir, and land areas near large bodies of water--especially the oceans--experience less variation in temperature . Because much of the land that constituted Pangaea was distant from the oceans, temperatures fluctuated greatly, and the interior of Pangaea probably included expansive areas of desert . Abundant red beds and evaporites such as halite support these conclusions, but evidence exists that the generally dry climate of the Triassic was punctuated by episodes of increased rainfall . The most important humid episodes were the Carnian Pluvial Event and one in the Rhaetian, a few million years before the Triassic--Jurassic extinction event . </P> <P> Sea levels began to rise during the Jurassic, which was probably caused by an increase in seafloor spreading . The formation of new crust beneath the surface displaced ocean waters by as much as 200 m (656 ft) more than today, which flooded coastal areas . Furthermore, Pangaea began to rift into smaller divisions, bringing more land area in contact with the ocean by forming the Tethys Sea . Temperatures continued to increase and began to stabilize . Humidity also increased with the proximity of water, and deserts retreated . </P>

Which era is known as the age of the dinosaur