84 Reineus — Jukes-Broicne Sf Hill — Gault and U. Greensand. 



(Lower Greensand) for the Greensand of William Smith, whicb 

 gave rise to much confusion. The true succession of the beds 

 was pointed out by Dr. Fitton in 1824, who suggested the name of 

 Merstham Beds for the firestone and greensand above the Gault and 

 ShanMin Sands for the sands below. The proposition of Webster 

 that the beds should be respectively called * Upper Greensand ' and 

 ' Lower Greensand ' finally prevailed, and these terms were adopted 

 by the Geological Survey in 1839 and have since continued in 

 general use. 



It was not until a later date that the accepted character of the 

 Gault and Upper Greensand as definite and distinct formations of 

 the Cretaceous System was called in question. Mr. Godwin-Austen 

 stated in 1850 that the Upper Greensand was a purely conventional 

 name, and that the diflferences between the fauna of the Devizes and 

 Blackdown Beds (Upper Greensand) and that of the Upper Gault 

 of Folkestone are only such as might be expected between arenaceous 

 and argillaceous portions of the same zone. He further added that 

 the Gault was not an independent formation, but merely the accumu- 

 lation of a given condition of deep-sea, synchronous as a whole 

 with that portion of the Cretaceous deposits which we call Upper 

 Greensand. Godwin-Austen's views were supported and confirmed 

 by the investigations of Meyer, Price, Dr. Barrois, and more especially 

 by the author of this memoir, who maintained that the Gault and 

 Upper Greensand were merely difiierent lithological facies of one 

 group of deposits. For the new group the name ' Selbornian ' is 

 proposed by Jukes-Browne after the well-known Hampshire village 

 made famous by Gilbert "White the naturalist. The name is the 

 more appropriate as the village is situated on the Malmstone, and 

 the Gault clays are well developed near by. The author does not 

 propose that ' Selbornian ' should supersede the terms Gault and 

 Greensand, but that it should be employed in a similar relation to 

 them as the general term Wealden to the Weald Clay and Hastings 

 Sands. It is strange that this new term, though constantly used 

 throughout the memoir, should not have found a place on the 

 title-page. In justification of its introduction the author states — 



" As a matter of fact gaidt clay and greensand are only two of 

 the different kinds of deposits that make up the group for which 

 the name Selbornian is now proposed ; it is only by a stretch of the 

 imagination that malmstone can be called greensand, inasmuch as 

 an ordinary malm contains but a small proportion of quartz sand and 

 still less glauconite, so that it is not a sand nor is its colour green. 

 There are large areas over which the formation is really a tripartite 

 one, and could actually be mapped as consisting of Gaidt, Malmstone, 

 and Greensand ; there are also areas where it consists wholly oif 

 Gault, i.e. of grey clays and marls ; others, again, where it consists 

 entirely of sand and sandstone ; and finally, there is a large area 

 where it is neither the one nor the other, but is represented by red 

 chalky limestone and red marl." 



Chapter iii, on the value of zones in the Cretaceous System, comes 

 in here somewhat parenthetically, but, as hinted in the preface, it 



