By A. J. Juices-Browne, B.A., F.G.8. 



333 



part of the series. It also occurs in parts of Hampshire and Surrey, 

 but it appears to be entirely absent in the East of Kent. Notwith- 

 standing* this variability of development it is certainly a distinct 

 portion of the series, and its fossils differ as much from those of the 

 Devizes Sandstone as these do from the fauna of the Lower Gault. 

 So far as I know it is never replaced by clay, and consequently this 

 zone of Pecten asper merits a distinct designation much more than 

 the rest of what is called Upper Greensand, because it is chrono- 

 logically newer than the sands and clays of the other two zones. 

 But if we retained the name Greensand for this zone it could not 

 rank as a subdivision of the first class, and if we called the other two 

 zones Gault we should have to include under that name the greater 

 part of what has hitherto been called Greensand. 



I think I have now demonstrated that we cannot continue to use 

 the terms Greensand or Upper Greensand in any definite chrono- 

 logical sense. They must be relegated to the limbo of general 

 lithological names, and share the fate of Greenstone, Trap, and other 

 terms that have done good service in their day, but are not adapted 

 to the present requirements of the science. 



The next proceeding is, of course, to find a new name which shall 

 be free from the defects of the old one. Here I am at once met by 

 the strong objection entertained by some geologists to the intro- 

 duction of any new name into the generally- accepted scheme of 

 classification. There are, however, many geological workers in 

 England and America who do not share this feeling, who cannot 

 regard the growth of some seventy-five years as too sacred and 

 antique to be interfered with, and do not believe that the classification 

 now in vogue is destined to last for ever as a perfect expression of 

 natural facts. It is strange that any votaries of geology should 

 need to be reminded that all science is progressive, and that progress 

 means change. I cheerfully admit that no change should be made 

 unless a very good case can be made out for the desirability of such 

 change; but my feeling is that if any part of our nomenclature 

 conveys a wrong impression of Nature's facts the sooner it is altered 

 the better. 



There are two methods of effecting the desired amendment in our 



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