How Earth is Formed

How Long is Long?

The earth formed along with our solar system around 4.6 billion years ago. This idea of ‘billions of years’ is a foreign concept for humans in that we are used to measuring time in minutes, hours, or days. This lab is designed to place geologic time into this human perspective. The goal is to illustrate how vast geologic time is by comparing geologic time with the simple task of counting to 100.

The following timeline provides some major events in human history and the evolution of life. You will use this timeline in later sections of the lab.

Years before Present

250 Founding of the U.S.

2750 Founding of Rome

3800 Construction of Stonehenge

9000 Founding of Jericho, the World’s First City

17,000 First Humans enter North America

30,000 Modem Humans enter Europe

100,000 First Anatomically Modem Humans

500,000 Homo erectus Discovers Fire

3,500,000 First Bipedal Human Ancestor (Australopithecus)

66,000,000 Extinction of the Dinosaurs

425,000,000 Arthropods are the First Organisms to Live on Land

540,000,000 Cambrian Explosion in the Diversity of Life forms

4,000,000,000 First Life on Earth

4,600,000,000 Earth is Formed

I. First you need to determine your scale of comparison. This is the human scale you are going to use to compare with the geologic time scale. For this exercise we are going to use the time it takes you to count to one hundred.

First, record the time it takes you to count to 100 (in seconds):

Time: ________ 60 seconds _________