

TKIASSIC STRATA OF THE SOUTH-WESTERN COUNTIES. 463 



sition took place in Devon and West Somerset between Keuper and 

 Bunter times, bridging over the hiatus marked by unconformity 

 in the midland counties. 



This proposition can only be proved by a comparison with the 

 results of Professor Hull's searching investigation into the constitu- 

 tion of the Triassic rocks of the midland counties. 



Lest I should be thought to cast doubt upon his determinations, 

 or in any way drag an already settled question into my individual 

 branch of the subject, I must state that I am practically unacquainted 

 with the Trias of the midland counties, and have not called in question 

 the existence of the unconformity between Keuper and Bunter in that 

 area which Professor Hull has so clearly demonstrated*. As far as 

 the beds subjacent to the Keuper are concerned, my conclusions can 

 in no way clash with those arrived at by Professor Hull in the 

 midland counties. I have been compelled to make these remarks, as, 

 from some undesigned coincidence to me unknown, Professor Hull 

 was under the impression that the paper I have had the honour of 

 submitting to the Society cast doubt upon conclusions he had esta- 

 blished, or ignored results he had obtained. 



Proof. — (a) As the Upper Marls of Somerset and Devon and the 

 Upper Keuper Marl of the midland counties directly underlie the 

 Ehaetic beds, there can be no hesitation in regarding them as the 

 same division. 



(6) When we find beds of similar general character and thick- 

 ness conformably underlying the Upper Keuper Marl in either area, 

 even though from the existence of the Mendip-barrier ridge their 

 sediments could not have commingled, we are forced on cumulative 

 evidence to admit the probability of synchronous deposition. 



This is the case with the Upper Keuper Sandstone of the midland 

 counties and the Upper Sandstones of Devon and West Somerset. 

 The general character of the Lower Keuper Sandstone is given by 

 Professor Hullf as " Thinly laminated micaceous sandstones and 

 marls passing downwards into white, brown, or reddish sandstone 

 with a base of calcareous conglomerate or breccia. " The Upper 

 Sandstones of Devon and Somerset may be characterized as red sand- 

 stones and rock-sand J, occasionally mottled with greenish spots, 

 frequently containing calcareous nodules, buff and grey in places ; 

 almost a marlstone near Bishop's Lydeard, brecciated at about 50 

 feet from their base on the south coast. In particular instances 

 modifications of this general character are noticeable. Near Wel- 

 lington and Milverton, for instance, the sandstone passes downwards 

 into a series of clays with intercalated beds of sand and occasionally 

 of fine conglomerate near the base : this variety almost deserves the 

 local epithet of waterstones ; it is about 50 feet thick. 



In some places between Milverton and Wellington the Upper 

 Sandstones are with difficulty separable from the conglomerates, as 



* Mem. Geol. Surv. " On the Triassic and Permian Bocks of the Midland 

 Counties," pp. 31, 87, 94, 97. 



t Mem. Geol. Surv. on Triassic &c. in Midland Counties, p. 10. 

 $ Quart. Journ. Geol. Soc. vol. xxxii. p. 378. 



Q. J. G. S. No. 135. 2 i 



