MARL-SLATE AXD LOWER MAGXESIAN LIMESTONE. 187 



and seems, before fossilization, to have had numerous shells at- 

 tached to it. Most of the traces of the latter are so obscure as 

 not to be determinable. Possibly they may be Lingulm; but 

 with them are two or three well defined specimens of Gervillia 

 antiqua, as well as something resembling Spirorhis microconchus. 



This locality is as it were the ultima thule of the Marl-slate 

 and its fossils — just as the adjoining quarry at Whitley is that of 

 the Magnesian Limestone and its fossils. These outliers form 

 the most northerly fossiliferous rocks of the Permian period in 

 Britain, assuming the sandstones and breccias north of the Sol- 

 way to be without fossils. It would be useless speculating as to 

 how much further north the strata to which they belong origi- 

 nally extended, though the existing evidence favours the idea 

 that they ranged in that direction far beyond their present limits. 

 Certainly there is none of that obscurity about the manner in 

 which the Magnesian Limestone terminates to the north as there 

 is in respect to the south. No portions of the Series, where last 

 seen in Durham and Northumberland, show the least traces of 

 becoming sandy and argillaceous, lite the Magnesian Limestone 

 of Derbyshire and Nottinghamshire. Nor do the fossils of these 

 two localities indicate any approach to a change either in the 

 distribution of species, or in their individual peculiarities, simi- 

 lar to that observed in the south. Indeed it is quite clear that 

 the northern termination of the Magnesian Limestone is abrupt 

 and owing to denudation, like the whole of its western edge 

 from Northumberland to Nottinghamshire. 



I may here mention, that at the south end of Whitley sands, 

 about a mile further north, there is a large boulder of Magnesian 

 Limestone that has been washed out of the Till. It is full of 

 fossils, but as it appears to have belonged to the middle portion 

 of the Series, I shall refer to them afterwards. Its occurrence, 

 however, as a boulder from the Till, points to the existence of 

 Magnesian Limestone north of its present limits so recently as 

 the Glacial period. 



Fulwell Water Works, &>~c. — The Sunderland and South Shields 

 Water Company, at the Pulwell works, have penetrated the 



