part 1] GAULT AjSTD lower GllEEJSrSAND jS^EAE, LEIGHTO]Sr. 60 



(3) The absence of any trace of Drift material along the supposed dis- 

 ruption-plane or in the overlying mass, and the lack of any structural 

 indication of Glacial distvirbance in the mass. Also the improbability that a 

 slab of soft Gault clay, greensand, etc., not less than 15 acres in area and 

 18 feet or more in thickness, could be turned over, pancake-fashion, and 

 dropped back onto a flat bed, without disruption or entanglement with Glacial 

 material, 



(4) The presence of a floor of unbroken iron-pan immediately above the 

 limestone, with evidence that it was in the same position before the Gault 

 was deposited {antea, p. 63). 



To these objections I may now add : — 



(5) The absence, so far as is known, of relies of similar limestone 

 in the Boulder Clays of the district. 



(6) The presence of similar limestone, containing some similar 

 fossils, in a bed immediately below the Gault at Long Crendon 

 (p. 41) ; also at Southcott (p. 38) and Littleworth (p. 39). 



(7) The extreme improbability, in view of its general arrange- 

 ment in the region, ^^ that the Upper Gault around Shenley Hill 

 was, as required by the inversion-hj'pothesis, ' little more than 

 40 feet in thickness' (K.P., p. 108) when the Lower Chalk was 

 deposited. 



Next, to consider some points of detail : — 



(8) 1 am unable, for reasons previously stated (p. 55), to 

 accept the statements (I) that the upper part of Silty beds seen 

 at Miletree Farm [and in other pits north of Shenley Hill] is 

 equivalent to the so-called ' tardefurcata bed ' and contains gritty 

 phosphatic nodules similar to those which elsewhere have yielded 

 the Mammillatus-fauna, and (II) that nodules of this kind in 

 the overlying beds have been * derived ' from it. The Silty series 

 is quite different in composition, and was accumulated under 

 different conditions, from the gritty glauconitic loams of Grove- 

 bury and Chamberlain Barn in which, as in France also (p. 58), 

 these nodules are always found and are reasonably held to have 

 originated. No palaeontological evidence is adduced for the pro- 

 posed correlation ; indeed it is definitely stated — 



' We could not break open a sufficient number of the nodules to enable us 

 to obtain any of the characteristic ammonites, although a few other fossils 

 [not specified] were found ' (K. P. p. 55). 



The unnecessary difficulties raised by the proposed correlation 

 affect the whole account given by Dr. Kitchin & Mr. Pringle 

 of the Miletree-Farm and neighbouring sections. 



(9) The palaeontological argument for the assumption that the 

 Lower Gault is absent in the Shenley and neighbouring sections is 



1 Borings south of Leighton have proved the full thickness of the Gault 

 to be about 230 to 250 feet, of which probably not more than 20 to 25 feet 

 is Lower Gault (antea, footnote, p. 6Q). See A. J. Jukes-Browne, ' The Gault 

 & Upper Greensand ' Mem. Geol. Surv. 1900, pp. 279, 284. 



