Geology of Ohio terrestrial environment since the Permian. For instance, the main subdivisions of the Pennsylvanian: the Pottsville Group, Alleghany Group, Conemaugh Group and Monongahela Group, along with the Early Permian Dunkard Group, are each more terrestrial than the last. The region was situated inland, experiencing terrestrial erosion as the Proto-North American continent of Laurasia collided with Gondwana to form the supercontinent Pangaea. Rocks from the end of Paleozoic are best exposed in road cuts along I-77, between Canton and Marietta, I-77 from Cambridge to Bridgeport and cliffs on the Ohio River north of Marietta to East Liverpool. For 245 million years, spanning
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