Sunday, August 19, 2012

Pennsylvanian (Geological Period)

Also known as Upper Carboniferous, the Pennsylvanian is a geological period of the Paleozoic era, which is divided into seven ones. The Pennsylvanian is marked by the existence of warm and moist weather, swampy lands, and the beginning of the evolution of large reptiles, as well as the formation of shale, limestone, and sandstone in America. The Pennsylvanian spans thirty million years, from 300,000,000 to 270,000,000 years ago.