The Epic Time Scales
The three numbers you see in the parentheses are the three largest units of time, known as the Epic Time Scales. These time scales are for units of time that are much larger than what is normally found on most traditional calendars. The unit of time range in size from 25,000 years to 250 million years. As such, these numbers are in parentheses because in everyday use, people will see no need to include them–just as most people see no need to include the initials “AD” or “CE” after the year while writing a check.
The three units of time found within the Epic Time Scales is as follows:
Eon (250 million years)
Genesis (2.5 million years)
Epoch (25,000 years)