4 ME. G. vr. LAMPLUCiH OX THE jr>X'Tiox OF [vol. Ixxviii, 



The attractiveness of my subject has been enhanced by the 

 recent pubhcation of a pa^^er by Dr. F. L. Kitchin & Mr. J. Prmgle, 

 in which it is argued that the strata above the Lower Greensand in 

 the Shenley Hill sections have been inverted by Glacial agency ; 

 also that there is an overlap of the Upper Gault upon the Lower 

 Greensand in this quarter ^ ; both of which suppositions can, I think, 

 be shown to be incorrect. The discussion of these points will be 

 dealt with sej^arately in the concluding part of this paper, after I 

 have described the sections of the new pits and the new featui-es. 

 revealed in the pits previously described. 



The general geological structure of the country around 

 Leighton Buzzard was shown in the paper of 1903 hj a sketch- 

 map reduced from the Geological Survey map (Q. J. G. S. vol. lix, 

 fig. on p. 235), and for the present purpose requires no further 

 illusti'ation. 



As the original interest centi-ed upon the pits under Shenley 

 Hill, I will first record the additional information obtained from 

 this place, and will then deal in turn with the new section s^ 

 east, north-east, north-west, and south-west of Shenley. The 

 position of the sections is marked on the outline-map (fig. 1, p. 2). 



II. Desceiptio>' or the Sections. 



The Shenley Hill pits. — Shenley Hill is composed of Gault, 

 based on Lower Greensand, and capped and protected by the 

 remnant of a dissected plateau of Glacial Drift, chiefly Boulder 

 Clay. The hill rises well above the 400 -foot contour, an Ord- 

 nance Trigonometrical Level of 457 feet being shown at less than 

 400 yards from the sand- workings. The workings themselves 

 are on the lower slope, with an avemge ground-level of about 

 350 feet, the slope continuing south-eastwards into the broad 

 Post- Glacial valley of the Clipstone Brook, where the 300-foot 

 contour is reached at about half a mile south-east of the sand- 

 pits. These are steep slopes for so ready a slipper as the Gault,. 

 and the consequences are apparent in most of the sections. 



Of the three contiguous pits mentioned in the previous paper,^ 

 which in 1902 were being pushed westwards into the steep slope of 

 the hill, and in which the fossiliferous limestone was sporadically 

 exposed, the middle one only — Harris's -^ — is now in operation. 

 Chance's on the north and Garside's on the south were abandoned 

 about 15 years ago, and the terminal sections in both are obliterated 

 by downwash, vegetation, and spoil; their final position is indicated 

 on the ground-plan (fig. 2, p. 5) which, if compared -^vith the 



^ ' On an Inverted Mass of Upper Cretaceous Strata near Leighton Buzzard. 

 Bedf ordshii-e : & on an Overlap of the Upper Gault in that Neighbourhood ^ 

 Geol. Mag. 1920, pp. 1-15. 52-62. 100-13. 



- For plan of the -n-orkings at that time,, see fig. 2 of the paper. 



^ Through a misapprehension of the spoken name (Gregory Harris), the 

 incorrect rendering 'Eigby Harris ' tv as applied to this pit in the previous 

 paper. 



