76 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [DcC. 6, 



Sometimes among the beds of this series may be seen a paler, softer, 

 and shelly bed, showing a sort of return to the conditions of the 

 lower beds. 



This series I have estimated as 50 feet thick, having measured 

 it bed by bed along the coast west of Dunraven ; it extends here a 

 distance of about one mile and a half, forming low anticlinals, but 

 dipping on the whole east of south. There is some uncertainty in 

 this estimate, from the presence of three small faults, for which I 

 have allowed 4|, 4|, and 8| feet respectively, the downthrow being 

 to the east. 



About 16 feet down occurs a bed with a great number of large 

 Chemnitzice; the wearing action of the sea has formed sections 

 through the columellse of many, as they lie horizontally imbedded in 

 the limestone .terrace below high-water mark. Owing to the hard- 

 ness and toughness of the beds, I have been unable to obtain spe- 

 cimens. 



The uppermost bed of the series, which I take as the line of 

 demarcation from the Lias, is a bed of conglomerate composed of 

 chert-gravel with arenaceous matter, 4 to 8 inches thick, loosely 

 held together ; the fossils of this bed are 



Plicatula intusstriata (abun- 

 dantly), 

 Modiola minima, 

 Ostrea leevis, 



Ostrea liassica, 



Pentacrinus, 



Cidaris-spines. 



Above this boundary-parting is a bed of smooth, pale-grey, con- 

 choidal limestone, containing 



Ostrea Hassica, I Modiola minima. 



Pholadomya glabra, J 



Above this begins the Ammonites-BucHandi series (the Planorbis- 

 beds being absent) with shale and argillaceous limestone containing 

 Oryphcea incurva, Myacites unionides, Cidaris (the same as that 

 occurring at the top of the Ehsetic series, and probably Cidaris 

 Edwardsii). 



Then, about 3 feet up, GrypJicBa incurva occurs socially in dozens, 

 with Ammonites Conybeari, A. rotiformis, A. Bucldandi, Lima, 

 Pholadomya amhigua, &c. 



At Dunraven Point the Carboniferous Limestone dips at an angle 

 of 43°, while the Sutton series lies in a gently curved arch upon 

 it. The Sutton series here is 40 feet thick, the same thickness as 

 near West, but the grey or Southerndown series is scarcely one 

 quarter of its former thickness; there is a small fault here also. 



The chief fossils which I have found in the Southerndown beds 

 are 



Pecten Suttonensis, 

 Lima Dunravenensis, 

 Pinna papyracea, 



Plicatula intusstriata, 



acuminata, 



Ostrea multicostata, 

 Ostrea Itevis, 



Inoceramus Eamsayi, 



These are enumerated in a tabular list as they occur in some of the 

 chief localities of this district (see infra, p. 79). 



