Chalk is formed from the skeletons of tiny animals called foraminifera.

Foraminifera lived and died millions of years ago. When they died, their skeletons fell to the sea bed and over the years layers of these skeletons built up.

Millions of years later movement in the earth's crust raised them above sea level and formed white cliffs.

The chalk is extracted for use in the building industry and for writing on chalkboards, sometimes it is coloured.