Dendrochronology, or tree-ring dating, is the science that assigns accurate calendar dates to the yearly growth rings produced by trees. Archaeologists have used this accurate and sophisticated dating method for nearly a century. Archaeological sites in the American Southwest were the proving ground for this method, which refined our understanding of the development and decline of past peoples. Events such as volcanic eruptions, earthquakes, forest fires, and insect infestations can also be understood through the use of tree-ring dating.