South Downs
range of hills in the United Kingdom
The South Downs is the chalk cliffs which are on the southern coast of England.
![](http://up.wiki.x.io/wikipedia/commons/thumb/b/b9/Seven_Sisters_cliffs_and_the_coastguard_cottages%2C_from_Seaford_Head_showing_Cuckmere_Haven_%28looking_east_-_2003-05-26%29.jpg/300px-Seven_Sisters_cliffs_and_the_coastguard_cottages%2C_from_Seaford_Head_showing_Cuckmere_Haven_%28looking_east_-_2003-05-26%29.jpg)
Chalk is mainly in the East of the country, and runs from France right up to northern England. It was laid down in a tropical sea during the Cretaceous period. The chalk was made by tiny plankton called coccolithophores in tropical conditions.[1]
Flint is often found in the chalk, and has a different origin. It has a different structure. It is made of silica, probably made by sponges.[2]
References
change- See also: Chalk