|Athro, Limited Earth Science Geologic Time Scale|
|Comprehending Geologic Time|
The classic analogy for illustrating the relative durations of parts of the geologic time scale is the yardstick: Imagine that all the earth's history is laid out on a yardstick. Recall that the original measure of the yard was the distance from the king's nose to the tip of his fingers. If one yard represents all of geologic time, then one swipe of a nail file across the tip of king's finger will remove all of human history...
You can use this calculator to create your own metaphor for geologic time. The history of the could be the the distance from your home to school - you can figure out where dinosaurs would be on the trip. Or the history of time could be the length of a class - and you could figure how much of the class you have to sit through before intelligence appears (if your class is 40 minutes long, human history begins in the last 1.5 milliseconds).
See also: The Geologic Time Scale