 |
|
| A B C D E F G H I J K L M N O P Q R S T U V W X Y Z |
| • HOME • ABOUT • CATEGORIES • USE OF TEXT AND IMAGES • NEWSLETTER   
|
era
A unit of geologic time usually lasting hundreds of millions of years. Eras are divided into smaller units of geologic time called periods.
Related category
• GEOLOGY AND PLANETARY SCIENCESource: U.S. Geological Survey
Also on this site:
Encyclopedia of Alternative Energy & Sustainable Living
Encyclopedia of History