﻿Vol. 6 I.] THE KELTIC DEPOSITS OP GLAMORGANSHIRE. 385 



18. The Rh^etic and Contiguous Deposits of Glamorganshire. 

 By Linsdall Kichardson, E.G.S. (Read May 24th, 1905.) 



[Plate XXXIII— Fossils.] 



Contents. 



Page 



I. Introduction ■ 385 



II. The Sully Beds 386 



III. Description of Sections. 



i. The Penarth District 388 



(A) Lavernock. 



(B) St. Mary's-Well Bay, Sully. 



(C) Cross Farm, near Dinas Powis. 



ii. Barry to Cowbridge 397 



(A) Coldknap, Barry. 



(B) Cadoxton. 



(C) Tregyff, near Cowbridge. 



iii. Cowbridge to Pyle 406 



(A) Hendre, near Pencoed. 



(B) Quarella Quarry, Bridgend. 



(C) Stormy Down. 



(D) Stormy-Down Cement- Works. 



IV. Additional Observations on the Sully Beds 410 



V. Conditions of Deposition of the Bhgetic Black Shales 414 



VI. On the White Lias of Glamorganshire, and on the Strati- 

 graphical Position of the White Lias 415 



VII. Summary ..... 420 



VIII. Paheontological Notes 422 



I. Introduction. 



In the autunin of 1904 I made, in company with my friend, 

 Mr. E. Talbot Paris, a detailed examination of the lihsetic and 

 contiguous deposits of Monmouthshire and Glamorganshire. The 

 results of my investigations in the former county have already 

 been made known, 1 and it now remains to record those in the 

 latter. 



Less than four years have elapsed since the officers of the 

 Geological Survey completed the re-survey of the Secondary rocks of 

 Glamorganshire ; and that part of the memoir on 'The South- Wales 

 Coalfield ' which deals with the Bridgend district was only issued to 

 the public last January. This being the case, it might be thought 

 that but little of interest would have remained to be noticed in 

 the present communication. However, whereas the officers of the 

 Survey were mainly concerned in the mapping of the deposits, 

 my attention was directed in most cases to the accumulation of 

 facts bearing upon the physical geography of the lihaetic Epoch. 



On a previous occasion I communicated to this Society a 

 theory, to account for the geographical distribution in North- West 



1 Quart. Journ. Geol. Soc. vol. lxi (1905) pp. 374-84. 

 Q. J. G. S. No. 243. 2 r 



