Vol. SS.] SUCCESSION IN THE N0ETH-WE3T OE ENGLAND. 529 



already been mentioned as occurring in the Siiverdale coast-section 

 at the same horizon. The band itself, which is exposed on the 

 shore on each side of the pier, is conspicuous on account of its 

 more shaly character and its yellower colour, as compared with the 

 beds among which it lies. It contains large examples of Gyrtina 

 septosa, together with specimens of Chonetes aff. comoides and 

 Productus JiemispJiericiis. The overlying beds exposed at low tide 

 to the west of the pier cannot be far below the base of the Upper 

 Dibunoi)hy1lum Sub-zone, and they contain abundant specimens of 

 Litliostrotion portloclci and other corals. Brachiopods are, on the 

 whole, rare ; but Productus cf. maximus and Pr. hemisphericus are 

 locally abundant. South of Grange promenade no exposures 

 occur on the coast, until we reach Seawood cottages ; here and 

 farther south-Avest, beyond Kent's Bank Station, the beds of the 

 Upper Dihunophyllum Sub-zone come on and the Nodular Gir- 

 vanella Band is well exposed. At Kirkhead End these beds are 

 cut off by a small north-and-south fault, which runs down the east 

 side of the Bay opposite Wyke House. This fault brings in again 

 the CJionetes-ix&. comoides Band in the corner of the bay close to the 

 railway-embankment. 



A good section of the strata at the base of the Upper 

 Dibunophyllitm Sub- zone is seen in the railway-cutting 

 immediately to the north. This includes a bed of shale, along 

 which horizontal movement appears to have taken place, as the 

 shale has been nipped out, and occurs in patches between the 

 harder limestone-beds above and below. 



On the west side of the Bay, south of Wyke House, the lower 

 beds of the Upper Dihunophyllum Sub-zone again appear at the 

 surface, and from here to Humphrey Head a continuous section 

 of these beds is exposed on the foreshore. This section affords 

 one of the best exposures of the Lonsdalia Beds to be met with 

 in the N'orth of England. It consists of 20 to 25 feet of grey 

 limestones, including, near the middle, a thin layer of black shale 

 containing specimens of CJionetes compressa, while the Nodular 

 Girvanella Bed at the base is exposed along the greater part of the 

 section. The nodules are very abundant; they form compact con- 

 centric incrustations round small fossils averaging about an inch 

 in diameter, and weather out prominently at the surface. Under 

 the microscope, tubes of Girvanella can sometimes be observed, 

 arranged concentrically round the nodules. The greater number 

 of the nodules, though undoubtedly due to organic agency, present 

 a somewhat obscure structure ; it seems probable, however, that 

 calcareous algae, and especially Girvanella^ directly or indirectly 

 contributed largely to their formation. 



The beds are particularly rich in corals, and contain reef -like 

 masses of Litliostrotion^ Lonsdalia floriformis, and CyatJiophyllum 

 regium. Brachiopods are scarce, but Pi'oductus giganteus and 

 Pr. liemispliericus occur locally in some abundance, while specimens 

 oi Schelliuienella cf. senilis occur in patches. The following is a list 

 of species collected from this interesting locality : — 



Q. J. G. S. No. 272. 2 q 



