Geological Society . 1G3 



These are covered by Dolomitic 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 Coalfields of 

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

 boundary of the South-Eastern Coalfield is to be looked for at a 

 sufficient distance east of Brabourne to allow of the presence of 

 the Carboniferous Limestone and Millstone Giit, as shown approxi- 

 mately 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 (1904-1907), proved the existence of the 

 Coal Measures at 1069 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 Fredville (1905-1907), 3 miles north- 

 east of Waldershare, reached the Palaeozoic floor at 1109^ feet, 

 and entered the same lower series of valuable coal-seams, dipping 

 at an angle of 17° (Journ. Boy. Soc. Arts, vol. Iv, 1907, pp. 456- 

 57). Further experiments have been carried on north and east 

 of Dover, but their results are not yet available for scientific 

 purposes. Thus a valuable coalfield 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 unexi)ected 

 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 3 miles south-west of 

 Canterbury, Instead, however, of Coal Measures, Upper Silurian 

 shales with Mono(jraptus priodon formed the Palaeozoic floor at 

 1072 feet below O.D. In the second, at Bobbing near Sittingbourne, 

 hard Silurian grits and shales occurred at 1070 feet below O.D. In 

 both borings the Silurian rocks are nearly vertical, and bear mnrks 

 of crushing The northern boundary of the South-Eastern Coalfield 

 is therefore to be sought in the district between Predville and 

 Chilham, and probably nearer to the former locality than to the 

 latter. 



The Silurian portion of the buried Palaeozoic floor is then traced 

 westwards thi'ough Ciiffe, on the Thames below Gravesend, to Ware 

 in Hertfordshire, and northwards through Essex to Harwich, Sutton, 

 and Culford (Bury St. Edmunds). To the south of this the Devonian 

 rocks occupy the area of London, and extend as far as the district 

 of Croydon. 



The varying thickness of the overlying rocks is also dealt with, 

 and details are given of three sections, at Kopersole, Chilham, and 

 Bobbing, in the hope that they may be useful to other explorers. 



