Gondwana Massif have been dated at 320–330 million years old, indicating that the subduction process initiated in the early Carboniferous.This was relatively short lived (lasting about 20 million years), and initial contact of the two landmasses occurred in the mid-Carboniferous, with broader collision during the early Permian. In the Devonian an island arc named Chaitenia accreted to Patagonia in what is now south-central Chile. Gondwana and Laurasia formed the Pangaea supercontinent during the Carboniferous. Pangaea began to break up in the Mid-Jurassic when the Central Atlantic opened. In the western end of Pangaea, the collision between Gondwana and Laurasia closed the
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