398 H. A. Baker — Charnian Movement in East Kent. 



Fig. 



5. Corresponding section of a specimen like that shown in Fig. 3 ; the ridge 



hardly projecting above the buttresses. 



6. Diagram of the probable disposition of the jaw-muscles : re. retractors, 



pro. protractors. The radial compass muscles are omitted, being 

 probably absent. The concavity of the false ridge is indicated by 

 a dotted line. The girdle is shown from the oral view, so that the 

 height of the processes and ridges is made to seem less than the actual 

 by perspective due to their inclined character. 



III. — Evidence suggestive of Charnian Movement in East Kent. 



By Herbert Arthur Baker, B. Sc, F.G.S. 



(WITH TWO MAPS: PLATES XXVI AND XXVII.) 



A COMPARATIVE study of the whole of the evidence concerning 

 the Palaeozoic floor beneath the South-East of England and the 

 manner in which the various members of the Mesozoics are disposed 

 upon it has led the present writer to conclude that the area, 

 originally defined by Professor P. F. Kendall, 1 over which the effects 

 of the operation of a " posthumous " Charnian axis may be discerned, 

 can be greatly extended, more particularly to the eastward. The 

 evidence, indeed, strongly suggests the presence of a second Charnian 

 axis beneath Suffolk, proceeding thence south-eastward to North 

 France. 



East Kent lies on the western flank of this alleged Charnian ridge, 

 and in view of the greater abundance of deep borings there, furnishes 

 the best area in which to study its influence upon both the Palaeozoic 

 and Mesozoic rocks. "With regard to the former, all the steadily 

 accumulating information concerning the structure of the South- 

 Eastern coalfield points to the presence, eastward of Kent, of a ridge 

 or barrier of a Charnoid or Malvernoid trend, which appears to have 

 been a potent factor during the deposition of the Kentish Carboni- 

 ferous, and which probably now separates the coalfield from that of 

 the Pas-de-Calais. In Kent the Lower Coal-measures, in the strict 

 sense, are absent, and have apparently never been deposited, and 

 there is no sign of Millstone Grit. The Middle Coal-measures lie 

 unconformably upon the Carboniferous Limestone. The latter has 

 been reached in several borings, particularly in North Kent, since 

 the general dip of the Carboniferous in Kent is to the south-west. 

 There is an area, a little to the north of Ebbsfleet, where, beneath 

 the "blanket" of Mesozoic strata, the Carboniferous Limestone 

 emerges from beneath the Coal-measures. For some five or six miles 

 to the south-west of this zone of Carboniferous Limestone, the 

 surface of the Palaeozoic floor in East Kent is occupied by 

 a succeeding "outcrop " of Middle Coal-measures, and these in their 

 turn are succeeded by the Transition Coal-measures which cover the 

 remainder of the surface of the known coal-basin to the south and 

 west, to and beyond Dover. The general strike of the strata in the 

 field is about 30° S. of E. and N. of W. A tendency of both Middle 



1 Kendall, "Sub-Report on the Concealed Portion of the Coalfield of 

 Yorkshire, Derbyshire, and Nottinghamshire " : Final Report Royal Comm. 

 Coal Supp. , pt. ix, 1905. 



