Geology of the Alps (300 Ma), the Hercynian or Variscan orogeny, in which the supercontinent Pangaea formed from Gondwana and Laurasia, was ended. East of the terranes that now form the Alps was the Paleo-Tethys Ocean. The effects of wind and water were able to chemically and mechanically erode and destroy the Hercynic mountain ranges. In the Permian, the main deposits in Europe were sandstone and conglomerate, products of erosion in the Hercynic mountain range. At the same time, crustal extension took place because the mountain range was isostatically unstable (this is called orogenic collapse). Due to extension, basins formed along the axis of
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