How are chalk hills created?

Question

How are hills originally created, white horse hill for example.

Answer 1

Chalk is mainly diatomaceous earth; a thick accumulation of microscopic, silicious shells. These would build up at the sea floor, and then would be uplifted later into a cliff.

Answer 2

I think the people above mean coccoliths, rather than diatoms.

Chalk is mainly made of tiny grains of calcium-carbonate which are the skeletons of long dead, single-celled organisms which lived in the sea once covering the area. Mostly, these are the plates of coccoliths (a photosynthetic algae which floated in the upper water column). But there are also sand-grain-sized shells of foraminifera, ostracods and other animals. There may be a bit of clay and silica (from diatoms, sponges etc) and other things as well in some chalks. The english chalk is nearly all coccolith plates. Some horizons have flint (=silica) nodules where silica has mobilised then precipitated in to chemically different bits that used to be burrows on the sea floor.

Anyway, the important thing is that the english chalk formed very very slowly from the 'raining' of dead coccoliths down to the sea floor, back in the Late Cretaceous (65-100 million years ago). After this, the land was lifted up, and then started eroding back.

Answer 3

Chalk hills are evidence of the long educational history of the earth. Early diatoms were responsible for the first buildup of classroom chalk when they right won the right to an education almost 1 billion years ago today! The study of mathematics produces the most chalk dust, which has accumulated over the aeons, one boring lecture after the next.

Answer 4

the white chalk stuff is chert and there may even be some talcum mixed with it .