284 GEOLOGY OF THE BRISTOL COALFIELD. 



Limestone with Univalves and yEgoceras Charmassei 2.3 

 Limestone with Lima and large Arietites ... 10.0 



Shales ... ... ... ... ... 3.0 



Blue Limestone, unascertainable. 

 Above is a iine layer of Septaria which here is extremely local, 

 but which may be met with and examined near Pill, on the 

 Portishead Railway. The Obtusus zone next follows, but this part 

 of the hill is so much covered with fields and cultivated ground, 

 that a good opening is to be seldom seen. A far better locality for 

 obtaining examples of Ammonites {Arietites) obtusus is in the 

 Portishead cutting. 



On attaining the altitude of ^23 feet above the sea level at the 

 cross roads and near the church, is a bluish marly limestone about 

 a foot in thickness, and corresponding to the marlstone. The stone 

 is so full of the shells of Am. Thouarsensis, A. radians, and 

 A. Aalensis, that the presence of the middle lias is fully justified. 



When the foundation for a cottage was excavated some time ago, 

 the late Mr. Sanders and the author observed the dark clays of 

 the Upper Lias, surmounted by about 12 inches of the Midford 

 Sands. It is upon these sands that the geologist first meets with 

 the Inferior Oolite, On the left hand side of the road, near the 

 cross roads, is a quarry for furnishing a supply of road-making 

 material. The limestone here has a dark colour from the oolitic 

 granules containing ten or fifteen per cent, of oxide of iron The 

 lowest two feet of this quarry is celebrated for the large proportion 

 of Gasteropoda they yield. It is also here that we collect the exquisite 

 Pleurotomariae so well described by Mr. Tawney. Immediately 

 above this, and immediately connected with it, is a stratum con- 

 taining a very large supply of Ammonites, Nautili, and Belemnites. 

 This layer of limestone underlies about eight feet of strata that 

 furnish the most of our Conchifera, which are, perhaps, better 

 examined in the next quarry, on the south side of the summit. 

 Many of the beds are celebrated for their furnishing so great a list 

 of Echini, Corals, and Brachiopoda. Here it is that we find that 



