310 PKOCEEDINGS OF THE GEOLOGICAL SOCIETY. [Jan. 18, 



Passing over for the present the bed of greensand, 9 feet in thick- 

 ness, which lies under the pebbly bed, and turning to the subjacent 

 clay, which is exposed to a depth of 23 feet in the course of the dig- 

 ging, we find it to contain, especially towards the upper part, — 



Pliosaurus of Shotover. Cardium striatulum. 



Ichthyosaurus of Shotover. Thracia depressa. 



Asteracanthus ornatissimus. Astarte Hartwelliensis. 



Ammonites — one species of the group Cucullsea. 



of A. polyphcus, A. triplicatus, or Perna. 



A. giganteus. Discina Humphreysiana. 

 Ammonites tfiplex. 



Towards the bottom of the excavation lies a layer of brown cracked 

 nodules, the cracks partly filled with bisulphuret of zinc. The 

 Ammonites and other fossils occur again below the nodules. No 

 specimen of Ostrea deltoidea being found here, but the shells of 

 Aylesbury being abundant, we may infer that it is the upper part 

 of the Kimmeridge Clay Avhich is here seen. 



The bed of greensand, 9 feet thick, which separates these two 

 clays, may now be considered. The mineral character of such a de- 

 posit is such feeble evidence, that without injustice to that the sand 

 may be referred to any part of the series between the Kimmeridge 

 Clay and the Gault. In appearance, however, it is like some of the 

 dark-green sand-beds at the back of the Isle of Wight (as at Black- 

 gang Chine), and it is not like the Portland Sand or the Iron-sands 

 of Shotover. I find in it none of the fossils of the Gault above, 

 nor any common fossils of the Portland rock or sands, but a few 

 examples of the Ammonite like A. polyplocus already mentioned in 

 the Kimmeridge Clay, Cardium striatulum, Thracia depressa, Pecten 

 arcuatus, Gorbida, and Wood. I do not find a trace of these fossils 

 in the pebbly drifts above, and do not suppose them to have been 

 transported from older strata into this greensand. On further 

 search I discover no sign of unconformity at the junction of the 

 sand with the subjacent clay, nor any mark of wasting on that clay; 

 but, on the contrary, a somewhat gradual introduction of the sandy 

 grains, so as to make an easy passage upwards from clay to sand. 

 I am therefore induced to believe that instead of this being, as at 

 first sight it might be thought, Lower Greensand, it is really a sandy 

 cap of the Kimmeridge Clay — perhaps the first stage of a change 

 towards the Portland series, but still to be classed with the clay. 



The information thus gathered from the section now discussed 

 may be increased by observing what occurs in the railway-cutting a 

 mile to the north-east of the Brickyard. According to the working- 

 section prepared by the engineer, Mr. Ward *, it appears that the 

 Gault is there found resting unconformably on ferruginous sands 



this band a specimen of Exogyra resembling E. haliotidea, which somewhat 

 strengthens my opinion that this thin layer is all that here represents the Lower 

 Greensand. It thickens towards the westward, retaining its worn sandy and 

 pebbly character. Possibly other observers may prefer to separate from the 

 Gault the five feet of sandy and pebbly layers, and call them Lower Greensand ; 

 but this is not my conclusion. — April 11, 1860. 



* I am indebted to Mr. Clutterbuck for the sight of this section. 



