The formation of fossils

In a nutshell

Fossils are the remains of living things that are preserved in rocks. Fossils provide evidence for how the Earth and living things have changed over time.

Fossilisation

Definition

Fossilisation is the process of how fossils are formed. They are most commonly found in sedimentary rock, because they are compressed by layers of sand and mud.

Science; Rocks; KS2 Year 3; The formation of fossils

1.	A plant or animal dies.
2.	The remains sink to the ground. They are covered by layers of sand and mud, over a long period of time.
3.	The sand and mud become compressed as more layers cover the remains. This makes a layer of rock form.
4.	The hard parts of the plant or animal, such as roots and bones, leave a print in the layer of rock.

What do fossils look like?

Fossils usually look like pieces of rock and can come in many shapes and sizes. Below are two drawings of what fossilised animals and plants look like.

	This is a fossil of a plant. Notice the veins and midrib (the thick part that runs through the centre of a lead) are visible as they formed an impression in the rock.
	This is a fossil of an animal known as an ammonite. Ammonites became extinct about $66\ million\ years\ ago$ and had spiral shaped shells. The shells are what become fossilised.