What are the White Cliffs of Dover made of and how have they been formed over time?

The White Cliffs of Dover are made of chalk, a soft, white limestone rock. They were formed over millions of years through the accumulation of tiny marine organisms called coccolithophores, which lived in the ancient seas that covered the area. Over time, the remains of these organisms were compressed and solidified into the chalk cliffs that we see today. Erosion from the sea and weathering have also played a role in shaping the cliffs over time.