Geologic Time Scale

Image 1: The Geologic Time Scale above is a helpful reference to use along with the information provided below. The left half shows a timeline of Earth’s geologic history which is split into Eons, Eras, Periods, and Epochs and how many millions of years ago (MYA) these occurred. The right half labels the major North American Events which includes the orogenies (mountain-building events) mentioned in this article. Events relevant to New York’s geology are outlined by a red rectangle. Geologic events are labeled with a cardinal direction (N, E, S, W) to show the region of the North American continent in which they occurred. For example, the “Grenville Orogeny (E)” occurred on the East coast.