1890.] on the Search for Coal in the South of England, 179 



the rest of the borings to the south termiDate in the Devonian or Old 

 Eed rocks, it may be inferred that the chalk of the North Downs 

 probably conceals the coal-measures. It must also be noted that 

 there are no Wealden rocks in the London area, and no Lower 

 Greensands, and that the Lower Oolites at their thickest are only 

 87 feet. The secondary rocks, which are of great thickness in the 

 midland and northern counties, thin off as they pass southwards 

 towards London, against the ridge of older rocks, as both Austen and 

 Prestwich have pointed out. 



It is therefore in the area south of London, rather than in that 

 immediately to the north, that the coal-measures are to be looked for 

 at a workable depth beneath the surface, and underneath the chalk of 

 the North Downs. It must, however, be noted that the line of the 

 South Wales syncline through Burford passes to the north of Ware, 

 and that there may be coal-measures in the northern parts of Essex 

 and of Hertfordshire at a workable depth. 



9. The Eeport of the Coal Commission was published in 1871, 

 and in the following year the Sub-Wealden Exploration Committee 

 was organised by Mr. Henry Willett, to test the question of tlie 

 existence of the Carboniferous and pre-Carboniferous rocks in the 

 Wealden area by an experimental boring. The site chosen was 

 Netherfield, about three miles south of Battle, in Sussex, where the 

 lowest rocks of the Wealden formation constitute the bottom of the 

 valley. The rocks penetrated were as follows : — 



Section ov Netheefield. 



Purbeck strata .. .. 200 feet. 



Portland strata 57 „ 



Kimmeridge clay 1073 „ 



Corallian strata .. 515 „ 



Oxford clay 60 „ 



1905 „ 



This boring showed that the coal-measures and older rocks are, 

 in that region, more than 1900 feet from the surface of the ground. 

 We may also infer, from the fact of the bottom of the bore-hole being 

 in the Oxford clay, and from the known thickness of the Bath Oolitic 

 strata in the nearest places, that it lies buried beneath considerably 

 more than 2000 feet of newer rocks. With this valuable, though 

 negative result, the Sub-Wealden Exploration came to an end. It 

 was a purely scientific inquiry, paid for by subscription, and largely 

 supported by those who had no pecuniary interest in the result. 



The experience of the boring at Netherfield showed that the search 

 for the coal-measures and older rocks of God win- Austen's ridge would 

 have to be carried out at some spot further to the noith, in the 

 direction of the North Downs. In the district of Battle the Oolitic 

 rocks were proved to be more than 1700 feet thick, and the great and 

 increasing thickness of the successive rocks of the Wealden formation 

 above them, which form the surfiice of the ground between Nether- 



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