xii PERMIAN FOSSILS, 



places between the Wear and the Tees.^ The railway cutting at Thrislington Gap 

 exhibits, in the ascending scale, the Sandstone, Marl-slate, and Compact limestone. 

 These members are exposed in the same relative position at several places north and 

 south of this locality ; and, by following them in the direction of their dip, they are 

 seen to pass beneath the other members of the series. The shaft sunk near the quarry 

 at Humbleton Hill for supplying the New Water-works of Sunderland, shows that this 

 Hill rests on a gritty limestone, with imperfect concretions, identical with that reposing 

 on the flaggy beds of brown limestone at Down Hill : this gritty limestone has its 

 uppermost beds exposed in the adjoining Lime-kiln Hole ; and these beds, which 

 contain a few fossils, such as Pleurophorus costatus, Leda Vinti, &c., are there seen to 

 be surmounted by a thick magnesio-calcareous bed, which has been quarried for a 

 number of years, and is clearly identical with the fossiliferous limestone (c) already 

 noticed, as occurring at Hylt on-North-Farm. By passing over the intervening valley 

 to Tunstall Hill, the fossiliferous limestone is again met witli ; but, in following the 

 axis of this hill, it is soon observed to be overlaid by a non-fossiliferous calcareous 

 rock, which either passes, or becomes changed, into the brecciated or pseudo- 

 brecciated deposit exposed at the foot of Tunstall Hope : this is continued down to the 

 coast, where it forms the bold and singular Cliffs extending from the Gorge near 

 Ryhope, south to beyond Seaham harbour. Half a mile north of Ryhope Gorge, at' 

 the south end of the Crags, the breccia is seen to rise from beneath the highest member 

 of the series, — the crystalline limestone (a), which is traced northward to Sunderland, 

 where it forms the entire mass of those varied and singular beds constituting the low 

 rounded eminence well known by the name of Building Hill. Numerous excavations in 

 Bishopwearmouth have convinced me, that the crystalline limestone passes downwards 

 into the brecciated rocks exposed in the Cliffs of the river Wear above the bridge, and at 

 Galley's Gill, precisely as at the South wick quarries and the south end of the Crags. I only 

 know of one place on the coast, south of the Wear, where any other member of the series 

 appears to be exposed, which is at the north end of Black Hall Rocks ; and here occurs a 

 breccia containing fossils the same as those characteristic of the fossiliferous limestone 

 of Humbleton Hill and Hylton-North-Farm, and passing under the highest member of 

 the series (a), which forms the remainder of these " Rocks" to their southern termination. 

 The beds at the south end of Black Hall Rocks have very much the aspect of the 

 dull compact thick-bedded limestone occurring in several places on the coast between 

 the Tyne and the Wear ; and they contain its characteristic fossils, namely Schizodus 

 ScJdotheimi, Mytilus septifer, &'c. At Hartlepool, the southernmost coast point of the 

 Permian limestone, the Cliffs consist principally of the oolitic variety of the highest 

 member — a variety which also occurs between tide marks, opposite Sunderland, and 

 near Roker Baths north of the Wear, associated with botryoidal, and other crystalline 



1 Permian fossiliferous limestones also occur in a few places a little south of the Tees ; but I have not 

 had an opportunity of examining them properly. 



