484 



PROCEEDINGS OP THE GEOLOGICAL SOCIETY. 



I' 



be 





that the Carboniferous Limestone at this 

 point formed the wave-washed cliff of the 

 Liassic sea, and that its caverns were 

 subsequently filled by Liassic deposits. A 

 longitudinal section at their junction 

 would then show similar conditions ; but 

 we cannot strictly adopt this idea, from 

 the fact that the same phenomena prevail 

 throughout the whole line of the Car- 

 boniferous Limestone, and that the veins 

 are continued to unascertained depths. 



The section now described was as it ap- 

 peared on the visit of the Members of the 

 British Association in 1863 ; but every 

 subsequent working alters its precise fea- 

 tures, though its general character re- 

 mains the same. 



1. Immediately to the south-east, and 

 parallel to the Marston road, may be 

 seen a vertical face of limestone contain- 

 ing Spirifera Walcottii, S. Munsterii^ 

 Echini, &c., unquestionably of Liassic age. 

 This appears to be a continuation of the 

 long face of similar limestone noticed 

 higher up the road. On entering the 

 quarry, this limestone is seen to pass 

 down as a vertical dyke, partly covered 

 by vegetation on the south, but which 

 appears to be about 6 feet thick. It is 

 composed of a wavy, thinly laminated, 

 yellow or bluish material, occasionally 

 conglomeratic, and somewhat resembling 

 marble. It has on its north side 



2. A breadth of 10 feet of regularly 

 bedded Carboniferous Limestone, showing 

 a considerable inclination to the south, 

 where it is cut off by the above. 



3. A nearly vertical vein, the sides of 

 which are composed of red, chocolate, or 

 variegated impure limestone, sometimes 

 with a central fissure stained with oxide 

 of iron, or containing ironstone, at others 

 filled with crystallized carbonate of lime, 

 9 inches. 



4. A thin band of Carboniferous Lime- 

 stone with organic remains, giving the 

 appearance of a vertical vein of that lime- 

 stone, 1 foot 3 inches. 



5. Dyke of conglomeratic Lias, passing 

 to the top, with occasional patches of 



