﻿Vol. 6l.l SEQUENCE IN THE BErSTOL AEEA. 229 



flexures rolls over at a small angle to the north, and the Palaeozoic 

 rocks are concealed from view for about 100 yards. They again 

 emerge in the cliff at Battery Point, and their age can here be 

 definitely fixed as Horizon (3. 



The abundance of Cleistopora in the flexed beds indicates the 

 upper part of K, and the small distance between these beds and 

 Horizon /3, at Battery Point, confirms this conclusion- Hence, we 

 have the ' Bryozoa-Becls ' (just below K,) in juxtaposition with the 

 upper part of K.,. This phenomenon necessitates a big fault, and, 

 if we assume a reversed fault to separate Horizon a (the ' Bryozoa- 

 Beds ') from the flexed beds of the upper part of K 3 , we have a 

 simple explanation of the series of small sharp flexures. This view 

 is in partial agreement with that expressed by Buckland & Cony- 

 beare more than eighty years ago. 1 



Tournaisian. 



Exposures and lithological character: — 



Horizon a (the i Bryozoa-Bed ') is well shown in a low cliff of 

 red limestone on the beach. 



The upper part of the Cleistoj^ora-Zone can be examined on the 

 foreshore, between the outcrop of Horizon a and Battery Point. 



The clathra tus-suhzone is excellently displayed at Battery 

 Point, and in the cliffs for some distance east of the point. 



The resupinata-suhzone, extremely rich in Zaphrentis, is 

 well seen in two quarries in the Portishead-Clevedon ridge, 

 that is : (1) A quarry, cut into the side of the Big Weston 

 Wood, which can be seen from the road; and (2) A disused 

 quarry a short distance up Nightingale Vale (past the large 

 quarry referred to below). 



Horizon y and the ' laminosa-Holomites 9 can only be made 

 out in poor exposures at the side of Nightingale Vale, between 

 the resupinata-qu&rry and the large quarry already mentioned. 



The C a ninia -Oolite is well seen in this large quarry; it has the 

 fossiliferous band at the base, and is capped by compact dolomites. 



Fauna": — 

 Modiola-Zone. 



Horizon a (the only part of the zone that is exposed) occurs, 

 as already stated, in a low cliff. The beds in the cliff are re- 

 markably similar to those at the same horizon in the Avon 

 section, and the fossiliferous strata contain an identical assem- 

 blage of organisms : namely, prolific crinoid- debris with abundant 

 JRhabdomeson, but very few other fossils. 



The title ' Bryozoa-Bed ' is well deserved, but the abundance 

 of bryozoans has been absurdly overstated. Rhabdomeson is the 

 only bryozoan that is at all common, and this fossil is not more 

 abundant here than it is in certain beds in the Cleistopora-Zone 



1 Trans. Geol. Soc. ser. 2, vol. i (1824) p. 246. 



2 Only the most interesting points are noticed. 



Q. J. G. S. No. 242. R 



