﻿Vol. 6 I.J CONTIGUOUS DEPOSITS OF GLAMOROANSHIKE. 389 



(A) Lavernock. 



The section at Lavernock is certainly one of the finest in the 

 country of the beds under consideration. The Rhsetic can be 

 studied in the foreshore and cliffs of the deeply-indented little bay 

 immediately to the north of Lavernock Point ; the White Lias 

 and the Ostrea-Beds succeed ; while round the Point, and as far as 

 St. Mary's-Well Ba3 T , Sully, are the planorbis-, angulata-, and 

 BucJrfandi-beds (pars), arranged in a gentle syncline. At St. Mary's- 

 Well Bay, the Rheetic again makes its appearance. North of 

 Lavernock Point the strata rise into a gentle anticline, with the 

 result that the Keuper makes its appearance. Thus Keuper, 

 Rhsetic, and Lower Lias can all be examined in this unrivalled 

 coast- section. 



Although brief reference has been made to the section by several 

 authors, 1 it has not received sufficient attention. The most 

 complete record is that given by Bristow ; but he mentioned 

 comparatively few fossils. For several reasons, a very detailed 

 section has been appended to the present paper (facing p. 392). 



The Keuper Red Marls are of the usual type : dark-red marls, 

 with greenish-grey zones. Above come the ' Tea-Green Marls,' 

 having, according to my measurements, a total thickness of 33 feet 

 4 inches. The most interesting feature in connection with these 

 marls is the occurrence in them of gypsum — a mineral that is 

 particularly rare in North- West Gloucestershire and Worcestershire. 

 Indeed, I have not found it in the marls of the sections which I 

 have studied in that district in any appreciable quantity. 



Above the ' Tea-Green Marls ' come the Sully Beds — a portion of 

 Etheridge's ' Grey Marls.' The line of demarcation between the 

 two series of deposits is necessarily an arbitrary one. The peculiar 

 lithic characters of the Sully Beds at Lavernock, and the fact 

 that John Storrie found ' . . . . some remains of the great Laby- 

 rinthodon, Mastodonsaurus . . . . ', in association with a number 

 of small teeth of Spliwrodus, a mandible believed to belong to 

 Palceosaurus, two teeth belonging to the same dinosaur, and 

 remains of Trematosawms, about 6 feet below the Rhsetic ' fish- 

 bed,' 2 all support the conclusion that the Sully Beds are more 

 intimately connected with the Rbsetic than with the Keuper. The 

 most useful evidence in support of this contention, however, was 

 obtained at St. Mary's-Well Bay (Sully), Cross, and Cadoxton ; 

 as will be shown later (pp. 395, 396, & 399). 3 



The uppermost marlstone of the Sully Beds is conspicuously 

 waterworn, some of the irregularities projecting at least 5 inches 



1 R. Etheridge, Trans. Cardiff Nat. Soc. vol. iii (1870-71) pt. ii, p. 39 

 H. W. Bristow, (Geol. Surv.) Vert. Sect. Sheet 47. 



2 Trans. Cardiff Nat. Soc. vol. xxvi (1893-94) pp. 105-106 & pi. 



3 [Since thi3 paper was written I have made a detailed examination of the 

 Watchet district ; and it appears desirable to state here that organic remains 

 are numerous in that district, in marlstones corresponding to these Sully 

 Beds.— June 16th, 1905.] 



