ANNIVERSARY ADDRESS OF THE PRESIDENT. IxXVii 



Triassic beds, to which at least, therefore, it must have been posterior. 

 Further, many of the transverse faults, which are numerous, run 

 directly to this great longitudinal fault, but cannot be traced beyond 

 it, showing clearly that those transverse faults cannot have been 

 anterior to the longitudinal fault. The great dislocating movement 

 of this district must, consequently, have been posterior to at least a 

 large portion of the Trias, and may have hQ&a. posterior to the Lias. 



In the more northern portion of this coal-field the strike is N.N. E., 

 and in the more southern N.N.W,, presenting the appearance of two 

 lines of elevation crossing each other at an angle of about 45°. If 

 however we consider the characteristic direction of the great move- 

 ment of this district as determined by the mean direction of the great 

 boundary fault above described, the orientation vrill be a few degrees 

 E. of N. and W. of S.* 



This conclusion agrees with that deduced from the Nottingham 

 and Derbyshire Coal-field with reference to a decided movement, at 

 least considerably after the commencement of the Triassic period, 

 and possibly after its conclusion. 



In Coalbrook Dale the general dii'ection of the main dislocations is 

 given as N.E. and S.W. by Sir R. Murchison and Mr. Prestwich, 

 who both recognise the lower Permian beds as graduating into the 

 Coal strata. The latter gentleman also considers that there is a dis- 

 continuity between the Triassic and Permian groups which Professor 

 Ramsay also recognizes generally in this region. Hence the prin- 

 cipal movement which dislocated this district must have been after 

 the lower Permian beds, and the best approximation, perhaps, we can 

 make to its epoch, is to refer it to the discontinuity above-mentioned 

 between the two great divisions of the Red Sandstone series. 



In the coal-field in the neighbourhood of Bristol the disturbed beds 

 of the coal-measures are covered unconformably by the Dolomitic 

 Conglomerate of that xieighbourhood. This conglomerate was for- 

 merly referred by geologists generally to the same period as the 

 Magnesian Limestone of the North of England, as being the only bed in 

 this region which could be regarded as the equivalent of that formation. 



Later observations of the geologists of the Survey have left this point 

 still undecided, but have tended to invalidate the opinion formerly 

 entertained. 



M. de Beaumont considers himself at liberty to place this Con- 

 glomerate at the bottom of the Trias. This would assign the same 

 epoch to the movement in the Bristol Coal-field as that above supposed 

 for Coalbrook Dale. Instead, however, of being N.E. and S.W., the 

 direction is here nearly N. and S. 



With respect to the Salopian coal-fields it may be sufficient to state, 

 that the general directions of dislocation are nearly N.E. and S.W. 

 In Denbighshire the Carboniferous Limestone and coal-measures 

 wrap round the Silurians of that region, on the eastern side, their 



* During the preparation of these sheets for the press, I have been indebted to 

 Mr. Jukes for a copy of part ii. vol. i. of the ' Records of the School of Mines,' con- 

 taining his description of the Dudley coal-field. It is confirmatory of what Prof. 

 Ramsay has had the kindness to communicate to me verbally. 



