350 Mr. Brockbank and Mr. C. E. de Range on 



note that only 396 yards of measures intervened between it 

 and Worsley Four Feet Coal, and that the Limestones 

 Measures have been removed by denudation before the 

 Permian era, and it appears highly probable that westwards 

 this denudation has been even more extreme, and that 

 workable coals are still nearer the surface ; but still 

 further westward the Upper Measures are again in 

 force, the Spirorbis Limestone appearing at Whiston 

 four feet in thickness. It is there overlaid by a purple 

 sandstone. 



The Spirorbis Limestone is present in nearly all the 

 western Coalfields extending from the Abberley Hills to 

 Ayrshire, a distance of 250 miles, with a mean width of 50 

 miles, so may be assumed to have been deposited over an 

 area of not less than 12,500 square miles. In several dis- 

 tricts there is evidence that before the deposition of these 

 Upper Measures great denudation of the Middle and Lower 

 Coal Measures had taken place, the Upper Coal Measures, 

 in an extreme case, resting directly on the Old Red Sand- 

 stone. And there is also good evidence that extensive 

 denudation took place before and during the Permian 

 epoch, rocks of the latter resting on every member of the 

 carboniferous series from the carboniferous limestones up 

 to the highest Upper Coal Measures known, which occur in 

 the Manchester district. Especially is this the case at 

 Levenshulme, where the actual junction of the two series 

 has been carefully studied by us, the base of the Permian 

 containing well-rounded and travelled pebbles of jasper, 

 limestone, Lydian stone, and vein quartz. The surface of 

 the Coal Measures beneath is a clear, well-marked division 

 of the most defined character, the uppermost beds con- 

 sisting of indurated dark, greyish-purple marls, with 

 numerous angular fragments of the same material, arranged 

 in a manner that would be called a breccia were the 

 material harder, and suggesting sub-aerial waste of an old 



