CHAPTER IV. 



THE RELATIONS OF THE UPWARE AND BRICKHILL 

 DEPOSITS TO OTHER BRITISH FORMATIONS. 



Our first care in considering the relations of the Upware and 

 Brickhill deposits to other British rocks, is to establish the close 

 relationship of these two deposits to one another. This is no 

 difficult task. Homotaxially the beds are similarly placed, and 

 there are many points of rock resemblance between them, amongst 

 which the identity of the included phosphatic nodules is the most 

 striking. But it is of the fossils that we have particularly to in- 

 quire, and these establish with decision the same fact of the close 

 affinity of the two deposits. Out of the 86 species found at Brick- 

 hill, 61 are common to the Upware Bed. The numerous types of 

 Brachiopoda, so special and limited in their distribution, which are 

 common to both areas, are of themselves a sufficient witness of the 

 nearness in age of the two deposits, only three of the Upware 

 species being absent from Brickhill. Of the Brickhill Polyzoa all 

 but two are found at Upware ; and the sponges tell the same story, 

 the Elasmostoma (Manon) macropora, Catagma porcatum, and 

 Verticellites clavatus, species so restricted in space and time, being 

 common to the two. Amongst the other organic groups the re- 

 semblances are however not so striking. 



The state of preservation of all the fossils in the two localities 

 is so precisely similar that the most practised eye fails to separate 

 them out with certainty from a mixed lot. 



Between the Upware and Brickhill areas is another well known 

 place, Potton in Bedfordshire, where the Neocomian Phosphatic 

 nodules have been worked for some years. This locality has been 



