Reston, VA – The U.S. Geological Survey (USGS) and the Association of American State Geologists (AASG) announced that they have developed an updated geologic time scale and color scheme for use in ...
Earth’s history spans 4.54 billion years, and scientists use the geologic time scale to divide it into eons, eras, periods, and epochs. By studying rock layers, fossils, and isotopes, they can ...