INTRODUCTION. xi 



yellow, and more or less charged with coralloidal, botryoidal, and other crystalline 

 forms (Building Hill) : in one district, this deposit splits into flexible laminse, as thin 

 as paper (Marsden) ; in another it is dull, fine grained, compact, and thick bedded ; 

 and at a few paces off, it is glimmering and completely crystallised : this member also 

 varies in chemical composition ; inasmuch as the crystalline portions are entirely 

 composed of carbonate of lime ; while the earthy, which form the principal mass of the 

 deposit, are essentially magnesio-calcareous in their composition. 



As regards those cases in which one or more members of the system are wanting 

 a reference may be advantageously made to the section at Tynemouth Cliff, which 

 exhibits the following* deposits in the order represented : 



Pseudo-brecciated limestone. 

 True brecciated do.^ 

 Beds of Freestone.^ 



Now I am led to conclude, that in this section, three members of the series are 

 absent ; — namely, the Marl-slate {e), the Compact limestone (d), and the Fossiliferous 

 limestone (c). My reasons for this conclusion are; 1st, the true brecciated bed 

 contains fragments of brown-coloured limestone, identical with that which occurs at 

 Down Hill, and other places along the Permian escarpment, north and south of this 

 locality; 2d, it contains fragments of the fossiliferous limestone ;^ and 3d, the Marl-slate 

 is entirely absent. The breccia was clearly not formed until after the deposition and 

 complete consolidation of those members the debris of which it contains. A parallel case 

 appears to obtain at Claxheugh, where the brecciated or pseudo-brecciated limestone 

 (b) is seen overlying the sandstone (/). In several places, the Marl-slate only is 

 absent ; as in the Cliff on the south side of Cullercoats Bay ; though at a few yards to 

 the north, between tide marks, near the line of the 90 Fathom Dyke, the Marl-slate 

 (here coloured black, with carbonaceous matter, as in the adjacent quarry at Whitley) 

 is distinctly seen intercalated between the sandstone, and the flaggy beds of brown 

 limestone. 



The order of superposition of the Permian beds is instructively displayed in several 



1 This bed encloses large boulders of limestone (some of -whicli are two feet in diameter) in the centre of 

 the cliff; but at tbe north end it completely loses its brecciated cliaracter, and becomes quite arenaceous 

 and compact. 



2 This bed is a true conglomerate, enclosing some rather large angular boulders of purple-coloured 

 freestone. 



3 I only succeeded in finding two or three specimens of fossiliferous limestone in the breccia at 

 Tynemouth Cliff; and these yielded me the following fossils : — Fenestella retiformis, Synocladia virgulaeea, 

 Acanthocladia anceps, Cyathocrinus ramosus, Productus horridus, Strophalosia Goldfussi, S. excavata, 

 S. Morrisiana, Streptorhynchus pelargonatus, Camarophoria Schlotheimi, S. glohidina, Trig onotr eta cristata, 

 T. undulata, Cleiothyris pectinifera, Epithyris elongata, E. sufflata, Pecten pusilhis, Monotis speluncaria, 

 Bakevellia ceratophaga, Pleurophorus costatus, and Pleurotomaria antrina. 



