﻿A: J. Jukes Brotcme — On the Vjjper Greemand, etc. 355 



rirestone of the Wealden area, and their equivalents of Pii'estone 

 and Chertj^ Sandstone in the Isle of Wight, The Warminster Green- 

 sand has also been generally accepted as another type of the Upper 

 Greensand, and of its claims more will be said hereafter. 



The Chloritic Marl. 



By whom this name was first proposed, and to what bed or beds 

 it was first applied, I have been unable to determine with any cer- 

 tainty, nor have the several geological fi'iends whom. I have consulted 

 been able to enlighten me on the subject. It seems probable indeed 

 that in its first application it was used rather as a descriptive term 

 than as a designation for any particular bed, and simply as a transla- 

 tion of the French " Marne cliloritee," 



Thus the earliest paper which takes cognizance of it is one by Mr, 

 Godwin^Austen on the geology of the south-east of Surrey, 1843.- 

 After describing the Lower Chalk of this district, he says, "This 

 portion of the series, taken in a descending order, slowly acquires 

 an admixture of sand and green earth, so as to become first a craie 

 cUoriUe, till by the further diminution of the calcareous matter we 

 reach the bright green beds of the Upper Greensand with Flicatula 

 inflata." 



This craie cliloritee appears to coincide in position with what was 

 afterwai'ds called the Chloritic Marl ; but a paper written in the 

 ensuing year by Prof. Forbes and Capt, L. L. B, Ibbetson, contains the 

 first actual mention of the term that I have been able to find, and 

 in this a more indefinite location is assigned to it.^ The authors 

 describe the Cretaceous system as seen in the Isle of Wight between 

 Sandown and Whiteclifi Bays, and the following passage occurs : "The 

 Upper Greensand corresponds nearly to the section at St. Catherine's 

 Down, presenting successively sands and clays, imder the name of 

 Chloritic Marl, siliceous bands, firestone and freestone, malm and 

 rag, the malm in a 3-feet bed, highly fossiliferous, surmounted by 

 26 feet of malm and rag passing into Chalk Marl," 



The whole description is somewhat confused ; but if any particular 

 beds are meant to be indicated by the name of " Chloritic Marl," 

 they would appear to be sandy marls and clays overlying the Gault- 

 clay, and forming the passage-beds to which I have previously alluded. 

 The authors may, however, have been mistaken in their identifica- 

 tion of the horizon, or they may have merely meant the term to be 

 descriptive of the lithological character of the beds. 



However this may be, the term Chloritic Marl had apparently 

 been associated with strata at the top of the Greensand or base of 

 the Chalk Marl before the year 184:8, and by this time the authors 

 above mentioned had arrived at more definite views regarding it. 

 Captain Ibbetson read another paper before the British Association 

 in this year " On the position of the Chloritic Marl or Phosphate of 

 Lime-bed in the Isle of Wight, "^ the substance of which was in- 



1 Proc, Geol. Soc. voL iv. p. 169. 



'^ Brit. Assoc. Rep. Traus. Sec. 144. 



3 Erit. Assoc. Kep. 184j, irai.s. Sec. p. 69v 



