I just finished reading Colin Fletchers book The Man Who Walked Through Time, and was fascinated and am fascinated by his struggles to comprehend the “geologic time” that you are faced with as you walk into the Canyon.  How does a person who lives ,perhaps 75 years, reconcile 200 million years?

My own pathetic attempts to put 200 million years into perspective have only really come up with the thought that if you look at our average lifetimes (about 75 years),  and you track a succession of people,  one after another,  the next person being born the day the previous died.  The number of consecutive lifetimes would total about 2.7 million  rounded off), in 200 million years.  Approximately the population of San Diego could have lived and died one after another in the time span of 200 million years.

While this is an interesting fact,  it still is not doing anything to really grasp the concept of these numbers.  I do not feel too bad, as Colin Fletcher spent months in the Grand Canyon contemplating this time span,  and by his own admission never fully grasped  it.  Can anyone?