March 6, 1890] 



NATURE 



419 



and that they were sufficiently near the surface to allow 

 of their being of great economic value. He further 

 specified the line of the Thames Valley, and the region 

 of the Weald, as possible places where they might be 

 discovered. 



These important conclusions were during the next ii 

 years generally received by geologists, with the exception 

 of Sir Roderick Murchison. The next important step in 

 the direction of their verification was that taken by the 

 Coal Commission of 1866-67, by whom Mr. Godwin- 

 Austen and Sir R. Murchison were examined at length, 

 and the results of the inquiry embodied in the Report by 

 Mr. Prestvvich. In the Report, Mr. Godwin-Austen's 

 views are accepted, and fortified by a vast number of 

 details relating both to the coal-fields of Somersetshire 

 and of France and Belgium. Mr. Prestwich also calls 

 special attention to the physical identity of the coals of 

 these two regions, and to the fact that the Carboniferous 

 and older rocks in both are similarly disturbed. He con- 

 cludes, further, that the coal-fields which now lie buried 

 beneath the newer rocks are probably equal in value and 

 in extent to those which are exposed in Somerset and 

 South Wales on the west, and in Belgium and France on 

 the east. 



In 1872 the Coal Commission Report was published, 

 and in the same year the Sub-Wealden Exploration 

 Committee was organized ^ by Mr. Henry Willett to test 

 the question of the existence of coal in the Wealden area 

 by an experimental boring. The site chosen was Nether- 

 field, near Battle, in Sussex, where the lowest rocks of the 

 Wealden formation form the bottom of the valley. It 

 was resolved to go down to the older Palaeozoic strata, 

 which were thought to occur at about 1000 feet from the 

 surface, or to carry the bore-hole to 2000 feet if they were 

 not struck before. The work was carried on under con- 

 siderable difficulties for the next three years, until in 1875 

 it had to be abandoned at a depth of 1905 feet, because 

 of the breakage of many hundred feet of lining-pipes, 

 coupled with the loss of the boring-tool at the bottom. 

 The section of the strata passed through is as follows : — 



Netherfield Section. 



Purbeck strata 

 Portland strata 

 Kimmeridge Clay - 

 Corallian rocks - 

 Oxford Clay 



Feet. 

 200 



57 



107.-? 



515 



60 



1905 



This section, although it yielded no information as to 

 the Palaeozoic rocks, showed that in this particular dis- 

 trict they are more than 1900 feet beneath the surface, 

 and revealed the great thickness of the Kimmeridge Clay 

 and Corallian rocks, sufficiently distant from the ridge of 

 coal-measures and older rocks, against which the Oolitic 

 strata thin away to the north, to allow of an accumulation 

 of Oolitic sediments to a thickness of more than 1 700 feet. 

 In this respect, therefore, it afforded unmistakable evi- 

 dence that the search for the ridge in question might be 

 carried on with much greater chance of success further 

 to the north, in the direction of the North Downs. The 

 great and increasing thickness of the successive newer 

 rocks of the Wealden formation, which form the surface 

 of the ground between Netherfield and the North Downs, 

 rendered it undesirable to repeat the experiment within 

 the Wealden area proper. Close to Battle, the Secondary 

 strata were of great thickness, and where the whole series 



r 'The Committee consisted of Profs. Ramsay and Phillips, Sir John Lub- 

 bock, b^ Hhilip Egerton. and Messrs. Thomas Hawicsley, Warington 

 .^myth. Prestwich, Bristow. Etheridge, Boyd Dawkins, and Topley. 



f 1 he precise boundary between these two groups is uncertain. If the 

 K.immendge Clay series be taken down to the Coralline Oolite, its thickness 

 will be 151a feet. 



of Wealden rocks were present, they were more than 

 1000 feet thick. 



For the next eleven years the problem remained where 

 it was left by the results of the Netherfield boring ; while 

 in the district of London, evidence was being collected 

 in various sinkings for water, which proved the existence 

 of the Palaeozoic ridge of rocks, Silurian and old red 

 sandstones, older than the Carboniferous, at about 1000 

 feet from the surface. Here, too, the Oolitic strata were 

 not more than 87 feet in thickness, at their thickest point 

 in the well at Richmond. The older rocks, moreover, 

 were inclined at a very high angle, as in the case of the 

 similar rocks underlying the coal-fields of Somerset, and 

 of Northern France and Belgium, and this implied the 

 existence of troughs of coal-measures in the synclinal 

 folds, in neighbouring areas. 



I come now to the last experiment, which has been so 

 fortunately crowned with success. In 1886, I reported 

 to Sir Edward Watkin that it was desirable, both on 

 scientific and commercial grounds, for a boring to be put 

 down in South-East Kent, in the neighbourhood of Dover, 

 and that the Channel Tunnel works under the Shake- 

 spear Cliff would be the best site for the experiment. It 

 was almost within sight of Calais, where the coal-mea- 

 sures had been proved at a depth of 1092 feet. It was 

 also not many miles away from the spot where a large 

 mass of bituminous material — which, according to Mr. 

 Godwin-Austen, was the result of the distillation of coal 

 from the measures beneath — had been discovered in the 

 chalk. Sir Edward Watkin acted with his usual energy 

 on my report, and the work was begun in 1886, and 

 carried on, under my advice, down to the present time. 

 The boring operations have been under the direction of 

 Mr. F. Brady, the chief engineer of the South-Eastern 

 Railway, to whose ability we owe the completion of the 

 work to its present point, under circumstances of great 

 difficulty. The strata passed through may be generalized 

 as follows : — 



Section at Shakespear Cli^, Dover. 



Feet. 



■500- 



660. 



Lower Grey Chalk, and Chalk-Marl 



Glauconitic Marl ... 



Gault 



Neocomian 



Portlandian 



Kimmeridgean 



Corallian ... 



Oxfordian ... 



Callovian ... 



Bathonian ... 



Coal-measures, sandstones, and shales and clays, with 1 



one seam of good blazing coal, struck at ilSo feet > 20. 



from the top of the bore-hole ... ... .. ... ) 



The coal-measures were struck at a depth of 1160 feet, 

 or 68 feet below the point where the coal-measures were 

 met with in the boring at Calais. It may also be noted 

 as a remarkable confirmation of Mr, Godwin-Austen's 

 views as to the abrupt thinning off of the Wealden strata, 

 that, although along the line of the North Downs the 

 Weald clay strikes towards the French coast, and is seen 

 at low water between Hythe and Folkestone, it and the 

 underlying Wealden strata are not represented in the 

 section at the Shakespear Cliff. 



It is too soon as yet to measure the full value of this 

 discovery near Dover, while our work is as yet unfinished. 

 We may, however, remark that the coal-fields of the 

 Continent, which have been proved beneath the newer 

 rocks in Northern France and Belgium, some 60 miles to 

 the west of their eastern outcrops, have now been traced 

 across the Channel, that they are at a workable depth, 

 and that we have now a well-defined base for further 

 researches in Southern England. 



W. Boyd Dawkins. 



