Northern Neivs. 89 



The cross section of this mass must have been of a wedge- 

 shaped form with the small end down, for, as a result of the 

 two successive fractures, the space between had been increased, 

 andjthe dislocated strip sank into the trough. But the strip did 

 not sink evenly, for owing" to the Southerly Fault being the older, 

 the rocks on that side of the trough would be lower, and the 

 edge of the displaced strip nearest the depressed side would sink 

 deeper. The opposite edge would be reared up, and a portion 

 of its fractured surface, with the coal seams, would be exposed 

 with a strike that would now be at right angles to that of the 

 rocks bordering the trough. The transverse faults probably de- 

 V eloped as the displaced mass adjusted itself in its new position. 

 The movements just described were in all probability gradual in 

 their character. Denudation would afterwards do its work, and 

 one result that seems clearly indicated is that the Don, or, 

 as it would then be, the Sheaf, for the Don diversion above 

 VVharncliflFe Gorge had possibly not occured then, followed the 

 line of fault. The probable outcrop of the Barnsley seam is 

 marked beneath the alluvium of the Don Valley on the sketch 

 map. Recent excavations in the neighbourhood of Brightside, 

 disclosed the seam at a depth and with a dip that would carry 

 it to the position indicated. 



We have here, therefore, an example of a trough fault dis- 

 tinguished by the fact that the faulted strip has subsided un- 

 equally, and has one long edge reared up above the opposite 

 one. It is also distinguished by the fact that, owing to the 

 differential rate at which the areas to the east and west of the 

 strip have subsided, one margin is much higher than the other. 

 There is evidence too that the rocks had undergone considerable 

 flexure before the second fracture occurred. The various move- 

 ments are therefore more complex in their character than would 

 be the case with a simple trough fault. Though this explana- 

 tion might seem more prosaic than the one it is oflfered as a 

 substitute for, it does not necessarily detract from the interest 

 of what must be considered to be the most instructive faulted 

 area in the whole of the coal-field. 



The report of the Corresponding- Societies' Committee of the British 

 Association, and of the conference held in London on October 30th and 31st, 

 has been issued. It contains the papers, &c. , referred to in our January 

 issue, as well as the discussions thereon. A valuable addition to the report 

 is the classified summary of the papers printed in the various proceedings 

 and transactions of the cori-esponding- societies. 



1906 March i. 



