﻿388 MR. L. RICHARDSON ON" THE RH^TIC AND [Aug. IQO5, 



III. Description of Sections. 



i. The Penarth District. 



Iu the Penarth district are included the outliers of Leckwith, 

 Penarth, Lavernock, and Cross : all capped by Lower Liassic 

 deposits. 



The Penarth section, it is almost superfluous to state, is a classic 

 one, as the name of the locality suggested to Murchison an alternative 

 denomination for the Ehsetic — the Penarth Beds. It is unnecessary, 

 for the present purpose, to discuss all that has been written on this 

 far-famed section ; but, for the convenience of those who desire to 

 study the literature, references are given in a footnote. 1 



The cliff-section at Penarth is disappointing. It is true that there 

 is a faulted syncline which has brought the Khaetic to the foot of 

 the cliff, but recently (August 1904) a slip has obscured the greater 

 part of the section which was available. Accordingly, if anyone 

 wishes to obtain details of value, it is necessary (to quote Mr. H. B. 

 Woodward) ' to climb an almost perpendicular cliff/ Fragments of 

 the several hard beds can be seen on the beach, and from an examina- 

 tion of their lithic structure it is often possible to state that such 

 and such a bed is present in the cliff-section ; but that is about all. 

 The details recorded by Bristow and Etheridge were obtained in a 

 railway-cutting ; and at the present time several such exposures 

 are available, especially at Penarth Docks. 



It is not necessary, however, to climb Penarth Head, for at Seven 

 Sisters' Bay the base of the Iihsetic is within 3 feet of the beach ; 

 while at Lavernock Point the beds are even more accessible and 

 convenient to examine than at Garden Cliff, Westbury-on- Severn. 

 The section at Seven Sisters' Bay is very similar to that at 

 Lavernock ; if anything, the beds are a little thicker, and continue 

 to increase in thickness until Penarth Head is reached. At 

 Penarth Head Mr. Woodward has noticed a band of limestone, 

 which reminded him of the Cotham Marble ; and I have observed 

 a similar bed — which probably represents the Sun-Bed of the White 

 Lias — at Lavernock (p. 393) and Barry (p. 398). On the beach at 

 Seven Sisters' Bay were pieces of limestone, probably from the 

 same horizon, that had been bored by Lithophagus (Lithodomus, 

 Cuvier) and encrusted with Plicatula intus-striata, Emmrich. 



1 H. T. De la Becbe, Mem. Geol. Surv. vol. i (1846) p. 253 ; T. Wright, 

 Quart. Journ. Geol. Soc. vol. xvi (1860) pp. 381-82 ; W. V. Guise, (Presi- 

 dential Address, 1863), Proc. Cotteswold Nat. F.-O. vol. iii (1865) pp. 117, 118 ; 

 H. W. Bristow, Geol. Mag. vol. i (1864) p. 236, & Rep. Brit. Assoc. 1864 

 (Bath) Trans. Sections, p. 50; B. Etheridge, Trans. Cardiff Nat. Soc. vol. iii 

 (1870-71) pt. ii, p. 39; Bristow & Etheridge, Geol. Surv. Vertical Sections, 

 1873, Sheet 47 ; T. Wright, ' Monogr. Lias Ammon. Brit. Is.' Pal. Soc. 1878, 

 p. 10; J. Storrie, Trans. Cardiff Nat. Soc. vol. xiv (1882-83) p. 100; H. B. 

 Woodward, Proc. Geol. Assoc, vol. x (1888) p. 529, & Pep. Brit. Assoc. 1888 

 (Bath) p. 900 ; J. Storrie, Trans. Cardiff Nat. Soc. vol. xxvi (1894) p. 105 ; 

 A. Strahan & T. C. Cantrill, ' The Geology of the South-Wales Coalfield : 

 Part iii — The Country around Cardiff' Mem. Geol. Surv. 1902, pp. 59-63. 



