Where Does Chalk Come From?
Deposits of chalk are found on some shores of the sea. A piece of chalk such as the teacher uses to illustrate something on the blackboard at school consists of the remains of thousands of tiny creatures that at one time lived in the sea. All of their bodies excepting the chalk—called carbonate of lime in scientific language—has disappeared and the chalk that was left was piled up where it fell at the bottom of the ocean, each particle pressing against the other with the water pressing over it all until it became almost solid. It took thousands of years to make these chalk deposits of the thickness in which they are found. Later on, through changes in the earth’s surface, the mountain of chalk was raised until it stood out of the water and thus became accessible to man and school teachers.