GHOLOQY OP TITIO AVON BASIN. 



27 



ill tlie valley of tlio Severn, between the calcareous cliaiii 

 now ti'eatod of, and that of Monmouthshire. Tlie limestone 

 rock, called i;lie Denny, in the mid-channel opposite the 

 mouth of the Avon, is situated exactly in the lino which 

 would connect the two calcareous chains. The strata, how- 

 ever, are nearly parallel to those at Portishead, dipping 

 N.W. at an angle of C0°." 



In the map appended to the paper from which I quote, 

 the Greater Clapton Fault is laid down as passing between 

 Wood Hill and West Hill. It would thus be continuous 

 with the line which separates Old Red Sandstone and Coal 

 Measures in the map which accompanies my paper on the 

 Portbury and Clapton district. On the other hand, in the 

 " Section from Portishead to Pamboi'ough Hill " (PL xxxii. 

 Sec. 3), the Pennant Grit is made to repose upon the Moun- 

 tain Limestone without the intervention of a fault. 



This I am persuaded is an incoi'rect interpretation of the 

 facts. I regard Denny Island, and not the Portisluiad 

 ridge, as the continuation of the King's Weston and Pen- 

 pole axis. I can find no evidence of a line of fault between 

 West Hill and Wood Hill, the latter hill being, I feel sure, 

 an outlier of the more northerly crest of the Portisliead- 

 Clevedon ridge ; in support of which I would point to the 

 similarity of trend and the similarity of dip. The limestone 

 ridge to the north is in connection with the Portishead- 

 Clevcdon axis, while I hold that the Coal Mcasui'o 

 ("Pennant") Grit cannot have assumed its position on tho 

 coast without the intervention of a fault. That this fault 

 has a tlirow of no small amount is shown by tho fact that 

 by it Old Red Sandstone, with high dip to the N.W., is 

 thrown into close juxtaposition with Coal Mcasiu'c San- 

 stone, probably Pennant, dipping 68° S.W. 



Dealing now with the sti'ata south of this fault, tlio 



