﻿Yol. 6 1.] THE RHiETIC DEPOSITS OF CrLAMOKGANSHIRE. 413 



pre-Liassic times), or the Rhsetic lias not been deposited. In either 

 case, it seems to me that it is necessary to invoke the assistance of 

 earth-movements to explain matters ; but, taking all the facts 

 available into account, it would certainly seem that at the localities 

 in question the Bhsetic had not been deposited, owing to an elevation 

 which was initiated about the time of the deposition of the Sully 

 Beds. On the westerly continuation of the Cardiff-Cowbridge anti- 

 cline at Bevos, near Tythegston, it is interesting to notice that the 

 relations of the Lias to the Keuper also suggest that the above is 

 the correct interpretation of the phenomena ; while at Sutton again 

 it is very doubtful whether the Keuper Conglomerate was ever 

 parted by a Rhgetic deposit from the Sutton Conglomerate. 1 



In the stretch of water which extended into the Lavernock 

 district, and the outlines of which had been modified by the earth- 

 pressures referred to above, the Sully Beds were formed, while the 

 ' Tea-Green Marls ' at certain other localities were undergoing 

 subaerial denudation. When the Bhaetic ocean gained access to 

 the British region it spread over the Lavernock area ; its waters 

 mingled with those of the Lavernock lake; the sediment too was 

 commingled, and the resultant deposit has the peculiar lithic 

 structure which characterizes Etheridge's ' Grey Marls ' and the 

 upper portion now denominated the Sully Beds. The appended 

 diagram (fig. 3, p. 412) will help to elucidate my views as regards 

 the relationship of the Pteria ( Avicula )-contorta Black Shales to 

 the subjacent marls and Sully Beds. Throughout the period during 

 which the Su]ly Beds were in process of formation, earth-pressures 

 may have affected the rocks, and it is especially desirable that 

 exact records should be kept of any sections showing the junction 

 of these beds with the overlying Black Shales, in order to see 

 whether there is definite evidence of any overlap of the upper 

 strata of the Sully Beds on to the ' Tea-Green Marls/ 



It appears imperative that these Sully Beds should be grouped 

 with the Bhsetic, and consequently a certain portion of the ' Tea- 

 Green Marls/ as defined during the re-survey of the district 

 (1892-1901), must be assigned to that series and removed from the 



1 The debated question as to the age of the Sutton Stone is now a thing of 

 the past : ' the whole of these beds may be regarded as the basement-beds 

 of the Lower Lias, representing the Ostrea-Beds and other portions of the zone 

 of Ammonites jplanorbis, and including perhaps portions of the zone of A. angu- 

 latus' (H. B. Woodward, 'The Geology of the South- Wales Coalfield: Pt. vi' 

 Mem. Geol. Surv. 1904, p. 62). I concur with this view. A little to the west 

 of the Caves, below West, near Southerndown, a quarry (now disused) had 

 been opened out in beds about the junction of the Sutton Conglomerate and 

 Stone, and from the spoil-heap were collected Chemnitzia (fragment), Anomia ? 

 (with Serpula), Astarte (Cardites, ? rhomboidalis, Tawney), Cardinia regulars, 

 Terq. (=C. suttonensis, Tawney), Gryphcea, Lima ( Ctenostreon) tuberculata, 

 Terq., Lima (Plagiostoma) sp. (small), Lima (Badula) hettangiensis, Terq. 

 (juv. = L. stibduplicata, Tawney), Ostrea onulticostata, Minister, Plicatula intus- 

 striata, Emmrich, Pecten valoniensis, Defrance, Mytilus imbricato-radiata, 

 Tawney, Lithophagus sp., Serpula (?J, and Astrocoenia gibbosa (Duncan). Lima 

 Terquemi is not uncommon, and this fossil alone demonstrates the non-Rhaetic 

 and the non-White Lias nature of the deposit in which it occurs. 



