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How Do Scientists Measure Earth Age?

Generally speaking, scientists have developed four different methods of determining the age of the earth. By using these methods, or a combination of them, the age of geological formations created by past events and even the fossilized bones of prehistoric animals can be determined.

Click image for detailed geologic column.
Based on the research done by scientists, the Geologic Column, a graph that illustrates earth age, was developed. The Column, with its names for the epochs and eras of time, illustrates what scientists think was taking place in earth history. A small version of the Geologic Column is pictured at the right.

Let's take a brief look at each of these methods.

The three primary methods are:

  1. Radiation Measurement
  2. Stratigraphic Superposition
  3. The Fossil Record

Once you finish looking at the methods, return here to do a Special Teacher/Student Geologic Time Activity

From these methods of dating, scientists have determined that the earth as we know it seems to be about 4.6 billion years old. It is theorized that the earth got its start as a result of what is called the "Big Bang nearly 6 billion years ago. The Big Bang theory holds that all the planets, stars, solar systems, galaxies, etc., are the result of a huge explosion that sent material speeding through space. As time passed, the gravitational force of larger chucks of material attracted the smaller chunks and formed the galaxies and solar systems we see today.