Vol. 58. ] DISTURBANCES IN BRAYSDOWN COLLIERY. 619 
The AvrHor said, in reply, that the rapid decrease in amount of 
overthrust and vertical uplift from the bottom coal-seam to the 
top one in the Radstock Series, as exhibited by the large overthrust 
at Radstock and the smaller ones at Braysdown, was a difficult 
problem, and he did not suggest that the ideas brought forward in 
his paper would meet all the difficulties of the case. Similarly with 
regard to the question of ‘dead ground,’ he did not suggest that 
this phenomenon was in every case due to earth-movements, and 
that there were no true ‘ wash-outs,’ especially in other districts. 
But, in this particular locality, the evidence of the polished and 
often rounded termination of coal against ‘dead ground,’ the strize 
on the roofs within the affected areas, the differential movement of 
the strata as shown by the overthrusts, together with the other 
evidence which had been brought for ward, pointed to the conclusion 
that in the great majority of cases the ‘ dead ground,’ ‘ thick coal,’ 
and ‘ thin coal’ were due to these differential earth- movements. 
He thanked the Fellows very much for the kind way in which 
they had received his paper; and he desired to thank Mr. H. B. 
Woodward for reading it, and for the kindly interest which he had 
shown in it throughout. 
