Vol. 51.] THE CRUSH-CONGLOMERATES OF THE ISLE OE MAN. 563 



41. TJie Crush-Conglomerates of the Isle of Man. By G. W. 

 Lamplugh, Esq., F.G.S. "With a Petrographical Appendix 

 by W. W. Watts, Esq., M.A., E.G.S. (Communicated by 

 permission of the Director-General of H.M. Geological Survey. 

 Read June 19th, 1895.) 



[Plate XIX.— Map.] 



Contents. 



Page 

 I. Introduction 563 



II. General Description of the Crush-Conglomerates 564 



III. The ' Skiddaw Slates ' of the Isle of Man 565 



IV. The Distribution of the Crush-Conglomerates 566 



(1) Summary of the Field-evidence. 



(2) Detailed Account of the Sections. 



(a) Coast Sections. 



(b) Inland Sections. 



(c) Sulby Glen. 



(d) Sections east of Sulby Glen, 



V. The Stratigraphical Relations of the Crush-Conglomerates . 579 



(1) The Method of Formation. 



(2) The Age and Duration of the Crushing. 



VI. Similar Rock-structures elsewhere in Great Britain 585 



VII. Concluding Summary 587 



I. Introduction. 



Among the Skiddaw Slates of the Isle of Man there occur in some 

 localities considerable thicknesses of a curious conglomeratic rock 

 which it is my object to describe and discuss in the following com- 

 munication. 



In spite of the extended development of this rock it has hitherto 

 received scant attention, the only noteworthy reference to it that I 

 have found in previous geological literature being the passing 

 mention by Henslow, as follows : — ' Near Ballaneah 1 I observed the 

 cliffs to consist of angular fragments of clay-slate embedded in a clay- 

 slate paste, and what is curious, these fragments are scarcely to be 

 distinguished from the base, excepting on the surface of the rock 

 which has been exposed to the action of the waves, where they 

 become sufficiently apparent by the fragments assuming different 

 tinges of colour, giving the specimen a mottled appearance.' 2 



In dealing with this matter I should have preferred to avoid for 

 the present the broader question of the general arrangement of the 

 Skiddaw Slates in the Island, but from the nature of the subject 

 this will not be altogether possible. 



1 Evidently ' Ballanayre ' of the Ordnance Maps. 



2 Trans. Geol. Soc. ser. 1, vol. v. (1820) p. 490. 



