“Geologists think the mountains were formed by several distinct tectonic events over the course of 500 million years, a span of time that represents a thick slice of the planet's geological record. The Appalachians once soared as high as the Rockies or even higher. They were most recently thrust upward about 290 million years ago, which makes these mountains older than the bones of the first dinosaurs. They predate the appearance of deciduous trees. They are older than flowers. There were mountains here before the Earth had ever seen anything as fantastic as grass. Some of the rocks were formed in the Precambrian Era, in that gray epoch when life was pondering a wholesale leap from one cell to many.”