﻿418 DE. C. A. MATLEr ON THE [Aug. I908, 



as revealed in the cliff along the western shore of the bay, it will 

 be found that only 10 feet of calcareous rock is exposed, and that 

 there the beds pass up into brightly- coloured shales and cherts that 



Pig. 5. — Decalcified Cyathaxonia--Se(?s in the cliff, Roaring Well Bay. 



have a decomposed appearance (fig. 5). The sequence (fig. 3 A, 

 p. 416, & fig. 4, p. 417) is as follows, in descending order -. — 



(iii) Black shale, poorly exposed at the base of cliffs of Drift, and sepa- 

 rated from (ii) by Drift. About 15 or 20 feet visible, 

 (ii) Shales ofTarious colours, usually ^veathering brown, with numerous 

 bright-red shale-bands and layers of chert. The beds have a 

 weatliered aspect, some of them are contorted, and some cleavage is 

 traceable in the lowest zones. They pass dov\n into (i). 



120 feet seen, 

 (i) Limestones with red shale-partings, the highest bed being discon- 

 tinuous and showing the effects of solution. 



10 feet to the centre of the anticline. 



The stratigraphy clearly shows that the 120 feet of shaly and 

 cherty material (ii) and possibly also the black shales (iii) are 

 remanie-beds resulting from the decalcification of cherty and 

 argillaceous limestones, shales, etc. as seen near by on the opposite 

 side of the anticline. The phenomenon is of the same character as, 

 but on rather a larger scale than, that described in the Cyatha.vonia- 

 Beds near the Bathing-Place north of Rush.^ The unexpected 



^ Quart. Journ. Geol. Soc. vol. Ixii (1906) p. 293. [In addition to the 

 examples of decalcification there given, reference should also be made to the 

 numerous instances in North Wales of the perish iug and solution of Carboni- 

 ferous Limestones at the outcrop, described in the ' Geology of Flint, Mold, & 

 Euthin' Mem. Geol. Surv. 1890, to which Dr. A. Strahan has been good 

 enough to draw my attention.— C. A. M., July 7th, 1908.] 



