3. The earth is old... Over 4.6 billion years old!

4. Scientists use a technique called radiometric dating! This uses different isotopes of various elements such as carbon (carbon dating) and lead.

5. The oldest rocks which have been found so far are about 3.9 billion years old. Some of these rocks include minerals which are as old as 4.2 billion years.

6. Let’s take a look at some important events throughout the history of the earth

7. 4.6 billion years ago: earth is formed, along with the other planets. 3.7 billion years ago: earth's crust solidified (104). 3.5 billion years ago: first life appears in oceans (120). 1.9 billion years ago: first cells with nuclei appear in oceans (248). 0.65 billion years ago: first multicellular organisms appear (348). 0.5 billion years ago: first land plants with inner vessels (359).

8. 245 million years ago: Dinosaurs appear (380) 200 million years ago: Pangaea breaks up (388) 65 million years ago: Age of Dinosaurs ends, (394) 3.5 million years ago: First proto-humans appear, in Africa (3.1 cm from end) 100,000 years ago: First Homo sapiens appears (1 mm from end) 10,000 years ago: Recorded human history begins (0.1 mm from end)

9. the history of the earth.... in a roll of toiler paper! 400 sheets long