ON THE RED CHALK OF ENGLAND. 



13 



Geologists generally consider the Red Chalk as really equal to the 

 Gault. Many of the fossils certainly are gault species ; others no 

 doubt belong to the Lower Chalk ; and, therefore, probably it is 

 better to regard it as an intermediate formation between the Lower 

 Chalk and the Lower Greensand, which comes into being when the 

 Gault and Upper Greensand have almost thinned out. 



One of the members of our Committee, Mr. Rickard, has been 

 good enough to make me an analysis of the Red Chalk of Speeton 

 and Hunstanton. The Speeton is as follows : — 



Carbonate of lime, with a little alumina 81.2 



Peroxide of iron 4.3 



Silica 14.5 



100. 



From Hunstanton — 



Carbonate of lime, with a little alumina 82.3 



Peroxide of iron 6.4 



Silica . . ... ...... . , . , . 11.3 



100. 



The latter of which agrees remarkably well with the colour of the 

 specimen, for the Red Chalk of Hunstanton is brighter than that of 

 Speeton. 



Two specimens of the borings of Kentish Town, one a red argil- 

 laceous and the other a siliceous mass, gave the following results : — 



Argillaceous — 



Peroxide of iron 6.5 



Carbonate of lime 13.5 



Silica and alumina (chiefly the latter) . . 80.0 



100. 



