﻿Vol. 6 1.] CONTIGUOUS DEPOSITS OP GLAMOKGANSHIKE. 411 



channels. 1 This inland sea, at the close of the epoch, had been 

 reduced by evaporation to a few comparatively- shallow lakes sur- 

 rounded by flats of marl. 



One of these lakes certainly existed in the Lavernock district, 

 and, as I have already pointed out, it would be in such areas that 

 transition-beds between the Keuper and the Rhaetic should be 

 sought for. 2 This lake was deepened, and its limits further 

 restricted, by earth-pressures which occurred at the close of the 

 Keuper Epoch. 



It is difficult, at present, to decide whether the earth-pressures 

 were more intense at the commencement or at the close of the time 

 when the Sully Beds were deposited. 



It is well-known that towards, or at the close of, the Carbon- 

 iferous Period, earth-pressures affected the Palaeozoic rocks of 

 most parts of the world, and among them Glamorganshire, and 

 caused the strata to be thrown into a number of anticlines and 

 synclines. The folds in Glamorganshire have been mapped and 

 admirably described by Messrs. Strahan & Cantrill, the main 

 axis being distinguished by these authors as the Cardiff- 

 Cowbridge anticline. As observed by Mr. Strahan, this anti- 

 cline as far west as Pendoylan was simply a broad arch, but in that 

 neighbourhood became compound. Mr. Cantrill has shown the 

 position of the subsidiary anticlinal fold : it trends a little north 

 of east and south of west, and brings to the surface at Stalling 

 Down, near Cowbridge, quartzitic and pebbly beds belonging to the 

 Old Red Sandstone. 



The movements which occurred at the close of the Keuper Epoch, 

 and affected the newly-formed conglomerates and marls, were 

 probably of upheaval along old anticlinal axes, although of course 

 they need not, and it would appear did not, agree with these pre- 

 cisely in position in every case. One of the main axes of elevation 

 at this time, however, was apparently along the line of country 

 traversed by the subsidiary pre-Triassic anticline referred to above. 

 On the hillside to the south of Aberthin, near Cowbridge, rock 

 thought to be Lower Lias is shown in the Geological-Survey Map 

 to rest directly upon the Keuper; and between this outlier and 

 Cow T bridge there is another outlier of the same rock, which is depicted 

 as resting upon the littoral Keuper. The Rhaetic has been shown 

 by the railway-cuttings at Cowbridge to intervene at those particular 

 localities between the littoral modifications of Keuper and Lower 

 Lias ; but usually in the Cowbridge outlier the Lower Lias rests 

 directly, and therefore non-sequentially, upon the Keuper. Similar 

 phenomena are observed atLlanbleiddian — a village near Cowbridge. 



Now, if deposition had continued unchecked from Keuper to Liassic 

 times, then everywhere the sequence would have been — Keuper, 

 Rhaetic, and Lias ; we should not have seen Lias resting directly 

 upon Keuper. Only two explanations can be suggested : either 

 the Rhcetic has been deposited and subsequently removed (but in 



i Quart. Journ. Geol. Soe. vol. Ix (1904) p. 186. 2 Ibid. p. 357. 



