Inverted Mass of U'p'per Cretaceous Strata. 7 



room for doubt. It is in the bed below the " Cornstones " that 

 ammonites of the varians fauna first begin to make their appearance. 

 The len tides of brachiopod-Hmestone at Shenley Hill may be 

 correlated most appropriately with the basal Cenomanian, which 

 Jukes-Browne tabulated as the sub-zone of Catopygiis columbarius. 

 No other construction can be placed on the combined testimony 

 of associated species representing four animal-classes. 



We need press the palaeontological argument no further. There 

 is a corroborative circumstance of much interest. The lithological 

 constitution of the limestone-lenticles, so well described by 

 Mr. Lamplugh/ is of a j)eculiar and distinctive type not matched 

 elsewhere in this country, so far as we know. But the basement- 

 bed of the Chalk {varians zone) at Matringhem, Northern France, 

 shows a remarkable similarity of characters. Although samples 

 of the rock from Shenley are as a rule distinguishable by their 

 ferruginous staining, the resulting difference is merely of a 

 superficial kind ; and it is possible to select specimens which are 

 inseparable from examples of the Matringhem bed except by the 

 aid of their labels. 



In the year 1918 a review of all these considerations served to 

 confirm our previous opinion that an error had been committed ; 

 and since Mr. Lamplugh's reading of the section had been accepted 

 by other experienced geologists who had visited the locality, we 

 concluded that the stratigraphical aspect of the series exposed at 

 Shenley Hill must be of a most deceptive character. In the hope 

 of securing data upon which to base a sound interpretation of the 

 succession, we examined the ground in October, 1918, and collected 

 fossils, first of all from the supposed Lower Gault overlying the 

 brachiopod-bed. Since then we have paid numerous visits to 

 the district and have searched for fuller information bearing on 

 the question at issue. 



A consideration of the stratigraphical, lithological, and palseonto- 

 logical evidence thus obtained has led to the conclusion that in the 

 sections at Shenley Hill where the masses of brachiopod-limestone 

 have been found, these lenticles, the inconstant layer of green sand 

 above them and the overlying Gault Clay, are in an inverted order 

 of succession. The overturned mass of strata does not in itself 

 form a complete unbroken series. There is definite evidence of one 

 non-sequence within it, and there may be a second one. We are 

 also able to show that the strata upon which the inverted beds 

 now repose do not constitute a simple conformable series. The top 

 of the Lower Greensand is here overlain unconformably by the 

 basal bed of the Upper Gault, which in the neighbourhood of 

 Shenley Hill lies transgressively upon older strata. 



1901, p. 96. J. Scanes, in Report by B. Pope Bartlett & J. Scanes, " Excursion 

 to Mere and Maiden Bradley, in Wiltshire " : Proc. Geol. Assoc, vol. xxvii, 

 pt. iii, 1916, pp. 122-5. 

 1 Op. cit., pp. 241-2. 



