Heports and Proceedings — Geological Society of London. 333 



proved by the boi'ing (1897-9) at Ropersole, where the same Pennant 

 Series occurred at 1,180 feet below O.D., and its extension in the 

 intervening area about 5 miles to the west of Dover by a boring under 

 the direction of M. Breton at Ellinge (1901-2), where the coal- 

 field was struck at 1,286 feet below O.D. 



In these three borings the strata of the Coal-measures are practically 

 horizontal, a fact which, in the opinion of the author, implies that 

 they form the bottom of a syncline witii its long axis passing from 

 Dover in a north-westerly direction parallel to the scarp of the j^orth 

 Downs. 



The boring at Brabourne (1897-8), under the direction of 

 Mr. Brady and the late Mr. Etheridge, gave the next fixed point in 

 the inquiry. It established the fact that, at the base of the North 

 Downs, the Palaeozoic floor consists of highly inclined strata (in the 

 opinion of the author, of Devonian age) at 1,789 feet below O.D. 

 These are covered by Doloinitic Conglomerate and Triassic marls, the 

 section being identical with that of the Mendip Hills in Somerset. It 

 therefore marks the position in Kent of the Pembroke- Mendip 

 anticline, which forms the southern boundary of the coal-fields of 

 Bristol and of South Wales. It follows that the south-western 

 boundary of the South-Eastern Coal-field is to be looked for at 

 a sufficient distance east of Brabourne to allow of the presence of the 

 Carboniferous Limestone and Millstone Grit, as shown approximately 

 on the map. 



These results, laid by the author before the Royal Coal Commission 

 in 1903, led to further experiments under his direction. The first of 

 these, at Waldershare (1904-7), proved the existence of the Coal- 

 measures at 1,069 feet below O.D., in two distinct groups, the upper 

 belonging to the Pennant Series as before with an average dip of 10°, 

 and the lower with an average dip of 20°, belonging to the lower 

 group of Coal-measures of Somerset, Gloucester, and South Wales. 

 The second, at Eredville (1905-7), three miles north-east of 

 Waldershare, reached the Palaeozoic floor at 1,1 09 J feet, and entered 

 the same lower series of valuable coal-seams, dipping at an angle of 

 17° (Journ. Roy. Soc. Arts, vol. Iv, pp. 456-7, 1907). Further 

 experiments have been carried on north and east of Dover, but their 

 results are not yet available for scientific purposes. Thus a valuable 

 coal-field has been proved over a large area, with its eastern and 

 western boundaries as yet undetermined, as shown on the map. 



Two further experimental borings to the north and west, carried 

 out under the author's direction in 1910-11, led to most unexpected 

 results. Hitherto the Coal-measures were either horizontal, or 

 dipping in the normal fashion without signs of faulting, and there was 

 every reason to believe that the Coal-measure trough would be struck, 

 on the first site, at Chilham, about tliree miles south-west of 

 Canterbury. Instead, however, of Coal-measures, Upper Silurian 

 shales with Monograptus priodon formed the Palaeozoic floor at 

 1,072 feet below O.D. In the second, at Bobbing, near Sittingbourne, 

 hard Silurian grits and shales occurred at 1,070 feet below O.D. In 

 both borings the Silurian rocks are nearly vertical, and bear marks of 

 crushing. The northern boundary of the South-Eastern Coal-field is 



