This time to count to one hundred is your human timescale. The time elapsed while you counted to one hundred was probably somewhere between 30 and 60seconds. This is a timescale that you can relate to, especially considered you just experienced it! You are familiar with this amount of time and you are comfortable with discussing events (like counting) that can occur over a period of 30 to 60 seconds.
Now you are going to start converting the human scale to the geologic scale. For the purposes of this exercise, you are going to consider each 100 years along the timeline provided above as equivalent to the time it takes you to count to 100. So, counting to 100 equals the passage of 100 years. Lets convert our dates before present to counting times (fill in the blanks):
This human scale is the amount of time you would have to count to reach the founding of the United States at your new scale. Now, perform these conversions for each of the other events on the timeline (fill in all the blanks):
Remember, the human scale represents the number of seconds you would have to be counting to arrive at a given event. Most people consider the founding of the United States or the founding of Rome to have occurred a long time ago. How do these dates compare with the time between now and the first appearance of humans?
Comparing these dates with the time when the first human occurred on the earth surface, there is a large difference since the first humans occurred approximately 100,000 years to present while United States and Rome were formed approximately 250 and 2750 years to present.
The Cambrian explosion is estimated to have occurred approximately 540 million years to present while the earth is approximated to have been formed approximately 4,600,000,000 years to present. The difference in the length of time is quite large.
Place humans within the perspective of Earths history? How does human history