OEOLOaY OF THE AVON BASIN. 



29 



fortahly on the Old Red Sandstone. Tliia iw in my opinion 

 impo.ssible. The Old Eed to the N. dips 75° N.W. The 

 limestone overlying it dips 18° S.B. There is not room for 

 the Lower Limestone Shales between tlie two. Nor is there 

 any sign of fault between the Old lied Sandstone of the 

 lane, upturned as it is, and the Lower Limestone Siiales 

 near the bifurcation of the road. , On my view (see Fig. ;i) 

 the repetition of the Old Red is duo to upfolding of the 

 strata, while the limestone of Fore Hill is brought down by a 

 Hat-lying downthrow from the limestone mass which, ere de- 

 nudation removed it, occupied its normal position over what 

 is now West Hill. The fault is thus analogous to that 

 which brings down the limestone patches in the Clapton- 

 in-Gordano coal-field. And neither in the one case or the 

 other is the throw of very great amount. 



The roll of the strata, by which I contend the upbringing 

 of tlio Old Red Sandstone on either side of Fore Hill to 

 have boon effected, is further evidenced by the limestone 

 of the quarry to the S.E. of tlie map. Did no such roll 

 exist, wo should expect upper beds of limestone here. The 

 beds are, however, low down in the Mountain Limestone 

 Series, closely resembling those of the Black Rock quarry 

 in the Avon section. On my last visit to tliis quarry I 

 found a characteristic fragment of an ichthyodorulitc of 

 Oracanthm (probably Milleri), a form also found in the 

 lilack Rock of the Clifton section. 



4. — Conclusion. 

 it only remains to point out, in conclasion, tliat the 

 ilexuros and faultings described in the last section date back 

 to pro-Mosozoic times — to those periods of disturbance 

 whicli usliered in and siuxieeded the deposition of the 

 rermiaii buds in Ihe nortlieni counties. Tliis is shown by 



