Vol. 6^.~] THE TOADSTONES OF DERBYSHIRE. 281 



which never comes to the surface in that county. If his recollection 

 served, there were only two distinct lava-flows then recognized ; 

 he gathered from the paper that the Author had identified three. 



As regarded the volcanic beds of County Limerick, which had 

 been referred to, there could be no question about their age. The 

 rocks consisting of ashes and lapilli, felspathic lava and basalt, 

 surmounted by the columnar felstone with crystals of augite, that 

 formed the crest of Knock Roe, were conformable to the Carboni- 

 ferous Limestone of Mount Lawrence and passed below the Yoredale 

 Shales ; while the i pipes ' or ' throats ' from which the lavas were 

 extruded occurred as isolated bosses outside the volcanic area. 

 The speaker, ever since his visit and survey of the district in 

 company with members of his staff, had recognized ' the Limerick 

 traps ' as representative of the volcanic lavas of Derbyshire, and he 

 was unable to discover any grounds for referring their age to the 

 Tertiary Period. 



The Author thanked the Fellows for the kind reception which 

 they had given to his paper, and replied that the few dykes observed 

 in Derbyshire were found in the agglomerates of the Graugemill 

 and Hopton Vents and in the upper lava near Priestcliffe. With 

 reference to the question of the relative ages of the sills and lava- 

 flows and tuffs, there was no doubt that the sills were intruded at 

 a later date. Although in several cases the sills came into contact 

 with lava-flows, in the case of the Tideswell-Dale sill the intrusive 

 rock had transgressed portions of the lower lava-flow, but had not 

 reached the top of that flow. 



