The term 'Geologic Division' refers to the four major divisions of geologic time: AGE, EON, ERA, and EPOCH. An AGE is the longest division of geologic time, lasting millions of years. An EON is the largest division of geologic time, lasting hundreds of millions of years. An ERA is a division of geologic time that is shorter than an EON but longer than an AGE. Finally, an EPOCH is the shortest division of geologic time, lasting thousands of years.