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The Geology of Devizes. 



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Fig. 7. — Structure of Chalk Rock (magnified sixty times). 



The Chalk Rock is found near the top of Morgan's Hill and 

 Oldbury Hill, and has been dug from shallow pits in many places 

 all round the borders of Salisbury Plain. 



7. Upper Chalk. Above the Chalk Rock comes the Upper Chalk, 

 a pure soft white Chalk with numerous layers of flint nodules. This 

 Upper Chalk is not well exposed anywhere near Devizes, so I do not 

 propose to describe it in detail, though near Salisbury it is some 

 600ft. thick, and in the Isle of Wight more than 1000ft. There is 

 no doubt that it originally spread across the whole Vale of Pewsey, 

 and, together with the underlying Chalks and Greensands, spread 

 westward across Somerset and Gloucester to the mountains of Wales. 



The whole of England was submerged beneath the ocean in which 

 the Upper Chalk was deposited, and it is not even certain whether 

 the summits of the highest mountains in Wales remained above the 

 surface of the water. Some of my readers may ask, " Where has 

 all the great tract of chalk gone to ? " The answer is that it has 

 been washed off all those parts where it is not now found; but 

 certain stones remain to testify to its former existence, for there are 

 few parts of England where chalk-flints may not be found in greater 

 or less abundance, and all these flints have been derived from the 



