FAUNAL SUCCESSION OF THE UPPER BERNICIAN 625 



assemblage presenting a much impoverished repetition of the 

 Great Limestone fauna. 



Productus aff. aculeatus (Mart.) 

 Productus concinnus, Sow. 

 Productus longispinus, Sow. 

 Productus muricatus, Phill. 

 Productus scabriculus (Mart.) 

 Chonetes cf. hardrensis (Phill.) 

 Bellerophon sp. 

 Petalodus acuminatus (Ag.) 



Faii}ial List : — 



? Dibunophyllid 



? Diphyphyllum lateseptatum 



M'Coy 



Athyris planosulcata (Phill.) 



Seminula ambigua (Sow.) 



Bisulcate Spirifers 



Martinia glabra (Mart.) 



Reticularia lineata (Dav.) 



Schizophoria resupinata (Mart.) 



Notes. — Producttis concinnus occurs in great numbers in 



the baked and crystalhne rock seen above the basalt at 



Haydon Bridge. Most forms in the above list are from 

 Fallowfield near Hexham. 



The Corbridge Limestone. 



Geographical Distribution. 



The limestone is to be seen in the neighbourhood of 

 Corbridge along several faulted outcrops. One of these runs 

 through the town, and is exposed by quarries near the potteries. 

 Another occurs near Aydon Castle. The closed outcrop of 

 brecciated limestone at Halton Shields is undoubtedly the 

 Corbridge Limestone. The bed sweeps round Stamfordham 

 on the east, and has been mapped as far as West Belsay."^' It 

 has not yet been correlated with any of the upper limestones 

 on the north of the Wansbeck. 



StratigrapJiical Character. 



A compact, thinly-bedded limestone resembling the lower 

 division of the Thornbrough Limestone. It rests upon sand- 

 stone. Thickness, i6 feet at Halton Shields. 



Palseontologically, as well as stratigraphically, the Corbridge 

 Limestone resembles the lower member of the Thornbrough 

 Limestone. 



* The older geological maps give a veiy different interpretation of the outcrops 

 from the later edition, and ai-e undoubtedly wrong. The data collected for tliis 

 paper support the results of the revision. 



