By A. J. Jules-Browne, B.A., F.G.S. 329 



great plains of chalk which once covered the surface of England, 

 and united England to France across the shallow trough which we 

 call the English Channel. 



Part II. — Classification and Nomenclature of the Strata 



Described. 



If we had merely to consider the neighbourhood of Devizes, or 

 even the County of Wiltshire alone, the simplest arrangement of 

 the Cretaceous Rocks would be to group all the Sands and the Gault 

 Clay together as a lower division, and to regard the several members 

 of the Chalk as an upper division. This was, indeed, the early 

 classification adopted by Conybeare and Phillips in 1822, and by 

 Fitton in 1827, but subsequent researches showed that it was not 

 really a natural one. The earliest names used for the beds below 

 the Chalk were Greensand, Gault, and Ironsands, the term Green- 

 sand being invariably applied by Dr. W. Smith to the sands above 

 the Gault, and including the Malmstone. 



The person chiefly responsible for the present nomenclature was 

 Thomas Webster, who proposed the terms Lower and Upper Green- 

 sand in 1824. They were suggested as a compromise, and only 

 because certain persons had mistaken the green sandstone which 

 occurs below the Gault at Folkestone for the true Greensand of 

 Wiltshire. Fitton strongly protested against them, but they were 

 retained by Murchison and others, who thought they were con- 

 venient names and never realised the force of the objections which 

 were brought against them. These objections were urged at various 

 times by Dr. Fitton, Mr. Godwin- Austen, and Professor Judd. 



The term Lower Greensand as a name for the Ironsands is bad, 

 because the general colour of these sands is not green, and because 

 it unites under a common designation two groups which are widely 

 separated in reality, one of them belonging to the upper series and 

 the other to the lower series of the Cretaceous System. The terms 

 upper and lower can only be logically applied to parts of the same 

 whole, thus we can speak of the Upper and Lower Chalk, or of 



