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
Continent craton or continental core. These have included Laurasia, Gondwana, Vaalbara, Kenorland, Columbia, Rodinia, and Pangaea. Certain parts of continents are recognized as subcontinents, especially the large peninsulas separated from the main continental landmass by geographical features. The most notable examples are the Indian subcontinent and the Arabian Peninsula. The Southern Cone of South America and Alaskan peninsula of North America are other examples. In many of these cases, the "subcontinents" concerned are on different tectonic plates from the rest of the continent, providing a geological justification for the terminology. Greenland, generally reckoned as the world's largest island on the northeastern