BRITISH ASSOCIATION. 



299 



Mr. Murchison observed, that the sandstones at Lymm appeared to 

 belong to that great series which he and Mr. Strickland had referred to 

 the keuper ; whilst those described by Mr. Dawes in the previous paper 

 were perhaps to be considered a part of the lower new red, which was 

 now acknowledged to belong to the carboniferous group. 



On the stratified and unstratified Volcanic Products of the 

 West of England, by the Rev. David Williams, 



This communication was supplementary to that which 

 Mr. WilHams made last year at Plymouth. Subsequent 

 investigation, on a far more extended scale, had confirmed 

 him in the results he then announced, viz. that granite, 

 gneiss, mica-schist, porphyry, greenstone, tufaceous ash, 

 breccia, grit, chlorite, talc, and clay slate, were all volcanic 

 products, and that no such distinction as the so called 

 " plutonic rocks" really existed in nature — they were, in 

 short, associated together by evidences of their common 

 origin, and connected together by a series of mutual de- 

 pendencies, and as such were capable of definite classifica- 

 tion, as erupted products, as rocks in situ, which have been 

 fused, semi-fused or had been in some other particular stage 

 of fusion, and as rocks simply altered by contact with in- 

 jected burning lavas. 



His object was to reduce the entire family of ancient 

 volcanic products within the scope of recognised laws, and 

 the ordinary operations of nature. He pointed to a diagram 

 he had constructed, of an ideal volcanic centre in a phasis 

 of activity, which, by admitting modifications to a greater or 

 less amount, he submitted might serve as an illustration 

 of the process of fusion and conversion, so far as the rocks 

 of the earth had been submitted to our view, throughout all 

 regions and all times. He supposed an internal nucleus of 

 white incandescent lava, whose outer border was surrounded 

 by a zone of gneiss, the zone of gneiss by an outer concentric 

 zone of mica-schist, and the mica-schist by any sedimentary 



