- Created by: amina
- Created on: 18-01-11 19:45
scientists once thought that the Earth was only 6000 years ols. Tpeople believed it because there was no way of testing the theory.
now we know that rocks provide evidence of how the Earth has changed nd clues as to its age.
rocks contain the history of the earth.
erosion- the earths surface is made up of layers. the oldest at the bottom. the layers are made of compacted sediment, which is produced by weathering and erosion. erosion changes the surfae of the planet over long periods of time.
craters-the surface of the moon is covered with craters from collisions with meteors. the ecraters from the earth have been removed by erosion
mountain formation- if new mountains were not being formed thewhole earth would have been worn down to sea level by erosion.
fossils- provide evidence of animals and plants and how they have changed in time.
folding-some roks look like they have been folded, this would require a big force to be applied over a long period of time.
radioactive dating- radioactivity of rocks decrease over time. measrues radioactivity of rolevels to find out how old they are.
estimate that the earth is around 4500 million years old. and when the earth was first formed it was completely molten and would have taken a long time to cool down.
the oldest rocks that hve been found on earth are about 4000 milllion years old.