CHAPTER VII 

 THE CHALK 



As we have traced the world's history written in the 

 rocks we have seen an old continent gradually submerged, 

 a deepening sea flowing over this part of the earth's 

 surface. Now we shall find evidence of the deepening of 

 the sea to something like an ocean depth. We are coming 

 to the great period of the Chalk, the time when the material 

 was made which forms the undulating downs of the south- 

 east of England, and of which the line of white cliffs 

 consists, which with sundry breaks half encircles our 

 shores, from Flamborough Head in Yorkshire, by Dover 

 and the Isle of Wight, to Bere in Devon. Across the 

 Channel white cliffs of chalk face those of England, and 

 the chalk stretches inland into the Continent. Its extent 

 was formerly greater still. Fragments of chalk and flint 

 are preserved in Mull under basalt, an old lava flow, and 

 flints from the chalk are found in more recent deposits 

 (Boulder Clay) on the East of Scotland, pointing to a 

 former great extension northward, which has been nearly 

 all removed by denudation. In the Isle of Wight the 

 chalk cliffs of Freshwater and the Culvers are the grandest 

 features of the Island ; while all the Island is dominated 

 by the long lines of chalk downs running through it from 

 east to west. Now what is the chalk ? And how was it 

 made ? The microscope must tell us. It is found that 

 this great mass of chalk is made up principally of tiny 

 microscopic shells called Foraminifera, whole and in crushed 

 fragments. There are plenty of foraminifera in the seas 

 to-day ; and we need not go far to find similar shells. 



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