The River Smithford to Lyell 



both of which we had previously found in the Upper 

 Greensand which occupied a similar position beneath the 

 chalk at Clifftown on the coast. 



At Clifftown the Greensand was of a grayish-green 

 colour, and contained grains of dark-green glauconite, 

 but here it was distinctly red, owing, as we saw on closer 

 examination, to numerous bright red particles, and also 

 to thin films of red matter between the sand grains. 



The difference in colour was due to the oxidation of 

 the glauconite and its consequent decomposition, one of 

 the products being a red oxide of iron. 



Beneath the Upper Greensand lay a bed of bluish 

 clay of a peculiarly smooth and buttery character. It 

 contained numerous fossils in a very perfect state of 

 preservation, many of them still possessing the beautiful 

 mother-of-pearl lustre which characterised the shells of 

 the animals when living. 



Conspicuous amongst these fossils were certain shells 

 which were coiled in a flat spiral, and which, when 

 broken open, were seen to consist of a number of 

 chambers like those of a recent Nautilus. These were 

 ammonites, and the two most commonly occurring in the 

 blue clay were Hoplites splendens and Hoplites lautus, 

 from which we concluded that the rock was the Gault. 



Below the Gault, and also dipping at about 5, was 

 another bed of sandstone not unlike the Upper Green- 

 sand in appearance. It was generally of a greenish 

 colour, but there were also a few beds of pure white 

 sand. The fossils, however, were unlike those of the 

 Upper Greensand, the most common being a large 

 oyster-like shell, Exogyra sinuata, known to be charac- 

 teristic of the Lower Greensand. The white and yellow 



in 



