SECTIONAL TRANSACTIONS.— C. 325 



already U8ed in another connexion ; moreover, other strata! groups could equally 

 well be described as ' epiric' 



The whole question is not one for British geologists alone ; it would be better 

 considered by an international committee who could define, in the first place, the limits 

 of the Permian marine sequence, and then possibly obtain some measure of agreement 

 concerning the position of the equivalent continental deposits. 



Afternoon. 

 Excursion to Burrington and Cheddar. 



Saturday, September 6. 



Excursion to Cattybrook, Aust, Damery, and Chipping Sodbury. 



Sunday, September 7. 



Excursion to Stanton Drew, Stoke Lane, Priddy, and Frome. 



Monday, September 8. 



Presidential Address by Prof. 0. T. Jones, F.R.S., on Some Episodes 

 in the Geological History of the Bristol Channel Region. (See p. 57.) 



Prof. A. H. Cox and Mr. D. A. Bryn Bavjes.— The 100-foot Base Level at 

 Cardiff. 



Well-marked terraces and base-levels occur on the eastern side of the Ta£E Valley 

 in Cardifi City and its immediate neighbourhood. The lowest is a gravel terrace on 

 which the central parts of Cardiff are built. Its southern or seaward margin is about 

 30 feet above O.D., rising inland to 50 feet. 



A higher platform is cut across gravelly drift and occasional solid at a height of 

 100 feet above O.D. in Cardiff, rising to 130 feet further north. 



Near Cardiff these platforms are only developed to any extent on the drift-covered 

 crop of the soft red marls of the Old Red Sandstone and of the Keuper Marl Series. 

 On the west side of the Taff their development has been hindered by the outcrop of 

 harder beds including the Radyr Stone, the local basement bed of the Keuper Series. 

 Their relation to the present Taff River is being further studied. 



The platforms are sufficiently extensive to represent considerable pauses in the 

 process of base-levelling and accordingly corresponding platforms might be expected 

 to reappear locally in some at least of the areas along the Severn Estuary. 



Prof. G. Delepine.— jfAe Dinantian Zones of Goniatites in the North of 

 France and Belgium. 



I would like, in the first place, to pay tribute to the memory of the late Arthur 

 Vaughan, whom I met in Bristol twenty-two years ago. He devoted much of his 

 time to showing me over the fine sections of this country around Bristol and in 

 South Wales. 



Everyone knows the Zones he established in the Dinantian, on Corals and 

 Brachiopods. They were used not only in the British Isles, but also on the Continent, 

 in Belgium and in the north and west of France, and proved successful in establish- 

 ing more accurately the connections between the Dinantian of this country and of 

 the other parts of north-western Europe. 



The difficulty, however, was to obtain satisfactory results when one comes to 

 the formations called Yoredale and Millstone Grit in the north of England, and 

 Namurian in Belgium. In this case. Shales and Grits come in ; Corals are often prac- 

 tically absent, Brachiopods are few and show little change on a large range. Thus, 

 for zoning, one wants to use other groups. Amongst these, the Ammonoids are 

 particularly suitable, because, generally speaking, their species have a wide 

 geographical distribution combined with a short vertical range. 



