The Conversazione. 



307 



Mr. Mackniel, for many years known as an active local Geologist, 

 and who lias kindly undertaken the office of curator to our temporary 

 museum, was also an observer on the spot. Professor Morris de- 

 scribed the fossil remains : and to these three gentlemen alone is 

 due the credit of preserving any notes of the Geology of the Wilts, 

 Somerset, and Weymouth Railway. 



Since Mr. Mantell's time, the geology of Westbury has attracted 

 much attention from the important discovery of the valuable iron ore. 

 Mr. Cunnington took this opportunity of correcting an error in the 

 published section. 1 The iron of Westbury is not derived from the 

 Lower Green Sand, which stratum is altogether wanting at West- 

 bury ; but from certain beds of pisolitic shale belonging to the 

 Kimmeridge Clay. In support of these views, he stated that the 

 shale from which the iron is smelted contains numerous layers 

 of the Ostrea deltoiclea, the characteristic fossil of the Kimmeridge 

 Clay, and that to the south of the works the iron shale is covered 

 with a bed of pure Kimmeridge Clay, with all the usual fossils of 

 that stratum. 



He further drew attention to the remarkable fact that these 

 Kimmeridge Clay beds yield in the furnaces both zinc and titanium ; 

 the former in the metallic state, the latter as titanium cyanide. 

 Unfortunately neither occurs in sufficient quantity to be of value — 

 the zinc on the contrary is injurious to the furnaces. He mentioned 

 that both these metals are absent from the Seend iron ore, which is 

 Lower Green Sand. Mr. C. also suggested that the presence or 

 absence of these metals might aid the geological chemist in deter- 

 mining the ancient rocks from which the Kimmeridge Clay and 

 other secondary strata derived their origin. 



Regarding the Oxford Clay of Trowbridge, Mr. Man tell mentions 

 that the abundance of fossils in some'of the beds is truly astonishing-, 

 especially the immense numbers of the shells and osselets of Cepha- 

 lopoda? "Often in exposing an area of clay or shale many yards 

 in extent, the whole surface was studded with the glittering pear- 

 ly shells of Ammonites of various species, and the numerous 



1 Geol. Jour., vol. vi., 1850. a [bid, i>. 314, 



VOL. XIII. — NO. XXXIX. Z 



