494 PEOF. T. G. BONNEY ON THE [Aug. I906, 



about 4 feet, part, if not all, of the uppermost foot being surface-soil. 

 Xear A, on the left hand, are traces, little more than smears, of 

 clay which might well be produced by muddy water percolating 

 from above along chinks in the rather disturbed Chalk. So this 

 hollow is a saucer or a trough. It is not easy to see how an ice- 

 sheet could have scooped out either. The former, I presume, would 

 require a gyratory action, after which the ice in melting mood must 

 have made restitution by filling up the hollow with Boulder-Clay ; 

 the latter would have to be the channel of a subglacial stream 

 which, however, did not transport any big pebbles. Another 

 difficulty I leave for the present, since it exists also at the second 

 pit. 



(2) Pit south-west of Newsell's Park. 

 Here, as Mr.Woodward has described, the rather infrequent flinfr- 

 bands dip roughly towards the north-west, at a less steep angle 

 than at Pinner's Cross, and the trace of a shear-plane can be seen 

 in the more southern wall of the inner part of the pit. 1 That 

 steepens on approaching the floor, till it makes with this an angle 

 of about 50°, and the rock adjoining it, for a thickness of perhaps 

 2 inches, has a slightly muddy aspect. That, however, might be 

 due only to greater dampness, but as the point was not important I 

 did not test it by analysis. The clayey patches on the wall of the 

 pit still remained, though the patch of ' brown earth with chalk 

 [fragments] ' had, I think, suffered a little in the interval between 

 Mr.°Woodward's visit and mine (and again between the latter 

 and our recent one), but I verified its presence and found traces of 

 two other smears of similar material running up the wall, to a 

 height of about 8 feet from the floor. I saw nothing to suggest 

 that the earthy material had been ' nipped up ' between masses of 

 Chalk, and its mode of occurrence was suggestive rather of its having 

 trickled from above, down some crack in the slightly-disturbed 

 Chalk-mass. . . 



The most remarkable feature, however, in the pit is the Boulder- 

 Clay which is seen beneath the Chalk rather nearer to the entrance 

 of the pit, apparently filling an arched cavity, 2 roughly 10 yards 

 in length and rising about 4 feet from the floor. I could find 

 nothing to suggest that the overlying Chalk was in any sense a 

 transported boulder, or that the Boulder-Clay 3 had been squeezed 

 into its present position, or anything in the relations of the two 

 calling for the thrust of an advancing ice-sheet. 



The following explanation, which Mr. Woodward does not con- 

 sider, seemed to me far more simple : that the Boulder-Clay has 

 filled a cavity which already existed in the Chalk, though it may 



1 See figs. 4 & 6, pp. 366-67, vol. lix (1903) of this Journal. 



2 On the occasion of my first visit, talus concealed the more eastern end, but 

 this was clear at my second one ; the Chalk overhung the Clay (apparently 

 with a natural surface) for at least a foot, and seemed to be descending behind it. 



3 It must lie below the curved shear-plane, and would accordingly require 

 a second big slab of chalk to be thrust over it, But at my second visit the 

 surface of the Chalk overlying the Clay seemed to slope behind the Clay in 

 more than one place. The N. and S. in Mr. Woodward's diagram must be 

 understood as used in a general sense, N.W. and S.E. being nearer the fact. 



