Natural Sciences and Technology Grade 5-B ... - Thunderbolt Kids

There was a flood and the river rose and covered the skeleton with
mud and sand.
Over time, more floods deposit more layers of sand and mud over
the skeleton. Over thousands of years, the bottom layers start to
become compacted and turn into sedimentary rock. Under the
ground, water carried substances from rock into each little space
where a bone had been. Rock took the place of bone. We say the
bones were fossilised. A fossil bone has the same shape as the
original bone but much heavier.
Millions of years later, the conditions of the environment above the
skeleton may change. The rock is eroded and weathered over time
by wind and water and the fossil is exposed on the surface. A
scientist sees the fossil and agreat discovery is made!
150 Earth and Beyond