80 DR FITTON. [1850-51. 



Tertiary strata were to be found, and hardly an out- 

 lier of any importance escaped his observation. Mr 

 Whitaker, who more than any other man has followed 

 in the footsteps of Prestwich over this large region, 

 referred in 1872 to the literature of the subject, and 

 remarked that the period 1841 to 1860 "might well 

 be called the ' Prestwichian period/ from the author 

 who first clearly made out the detailed structure of 

 the London basin." l ' 



Notebook entries for August 1850 record detailed de- 

 scriptions and sections made when on a tour in France. 

 The districts round Boulogne, Glermont, and Beauvais 

 were again explored, and the repeated exhibition of 

 " drift" at Beauvais, and its resemblance to that near 

 Marlborough, attracted his attention. The Abbe Mail- 

 lard was Prestwich's companion at Bracheux for an 

 examination of its sands. Epernay was the locality 

 from which he dated in September, where he was 

 joined by " Morris and Haines," and on this occasion 

 copious notes were made on the " Sables de Billy." 

 Those repeated visits to Epernay bore rich fruit. 



With the growth of geological knowledge questions 

 continually arise with reference to geological nomen- 

 clature. Perhaps no names of formations have given 

 rise to more discussion than those of Upper and Lower 

 Greensand and Neocomian. The views, therefore, of 

 Dr Fitton one of the old masters of geology, and 

 the chief English authority on the Cretaceous strata 

 will be read with interest : 



W. H. Fitton to J. Prestwich. 



53 UPPER HARLEY STREET, 15th March 1851. 



MY DEAR SIR, I hope you are making good progress with 

 your paper ; and I wish to mention to you (as it may save you 



1 Mem. Geol. Survey, vol. iv. p. 395. 



