336 DE. A. M. DAVIES AND ME. J. PEINGLE ON [June 1913, 



The question of greatest general interest suggested by the 

 ■Calvert borings is whether productive Coal Measures may be 

 present in that portion of the Palaeozoic floor which they have 

 shown to come so unexpectedly near the surface. The answer to 

 this question must at present be very uncertain, and I would simply 

 make the following remarks : 



(1) The Midland Coal Measures show evidence, by the coalescence 

 ■of seams, attenuation, and overlap towards the south, that a barrier 

 of older rocks must exist in that direction. The occurrence of pro- 

 ductive Coal Measures at Burford (whether they are productive or 

 unproductive at Batsford does not appear from the published state- 

 ment) shows that by that latitude the barrier has been crossed. 



(2) Carboniferous Limestone is known to occur at Northampton, 

 and, by inference from the pebbles in the Permian conglomerates, 1 

 also beneath the Forest of Arden or its neighbourhood. Its absence 

 at Batsford, half way in a straight line between Northampton and 

 the Porest of Dean, along with its overstep by Coal Measures 

 between that Forest and the Porest of Wyre, renders it quite 

 possible that in the Calvert area Coal Measures might rest directl)' 

 upon the Cambrian rocks. In this connexion it may be noted that 

 the Lias of Calvert, while showing relations to that of the Badstock 

 area in respect of its overlap, shows neither the attenuation nor 

 the calcareous composition which are there associated with nearness 

 to an extensive mass of Carboniferous Limestone. 



Further knowledge is needed before any definite conclusion as 

 to the existence of Coal Measures can be reached ; and the shallow 

 •depth of the Palaeozoic floor makes that further knowledge com- 

 paratively easy to obtain. 



Mesozoic Overlaps on the Palaeozoic Floor. 



It may be useful to summarize here what is known as to the 

 progressive submergence, with interruptions of partial emergence, 

 of the Palaeozoic floor of the South-East of England. 



(1) The Charmouthian overlap (hemerae raricostati to jamcsoni) 

 is now known at Calvert and at Brabourne ; reasons have been 

 given for believing it to exist at Bletchley also ; and, from an 

 examination of the Bopersole cores, it is thought that when the 

 fossils are extracted and identified they will prove it there also. 

 At Calvert there must have been a temporary submergence in the 

 hemera raricostati, followed by a short emergence before the main 

 Jamesoni transgression. Similar oscillations are known to have 

 occurred in the Badstock area, where remanie fossils of the rari- 

 costatum zone are found at the base of the armatum zone in some 

 places, though in others the former zone is present. At Yobster 

 it rests upon the Carboniferous Limestone : elsewhere in the 



1 H. T. Brown, Q.J.G. S. vol. slv (1889) p. 27 & table on p. 24 ; W. W. King, 

 ibid, vol. lv (1899) pp. 122, 123. 



