498 



MESSES. WHITAKEK AND JTJKES-BEOWNE ON [Aug. 1 894, 



Upper Greensand. Some resembling the Upper Green- 

 sand at the Wallingford and Moulsford borings. 

 Specimen from 939 ft. 8 in. : dark-grey plastic 

 Chalk Marl with many glauconite-grains, enclosing 

 bits of a harder or drier, more glauconitic marl. 

 After treatment witb acid and washing, a bit left 

 about two thirds of its bulk, consisting almost 

 wholly of quartz and glaucouite. Probably Chalk 

 Marl has been carried down by the boring-tool into 

 the sand. Specimen from 942 ft. 8 in. : hard grey 

 marl full of grains of quartz and of glauconite. 

 Specimen from 956 feet : calcareous malmstone, 

 having a matrix of granular calcite, with many 

 angular bits of calcific shell, many sponge-spicules 

 and minute scattered grains of quartz and of glau- 

 conite. This slide also shows a great number of black 

 specks (pyrites?) which fill chambers of very small 

 foraminifera (TextuJaria and others). Specimen 

 from 956 ft. 8 in. : hard, compact, grey stone, sandy, 

 micaceous, fine-grained. Specimen from 960 feet: 

 hard, compact, grey sandy stone, with some calca- 

 reous matter. Specimen from 968-970 feet : fine- 

 grained sandy stone like the last, but with little 

 calcareous matter 



[Gault, 

 264 feet,] 



f Gault [clay]. Became dark and sticky 

 at 994 feet (sample brought up dry). 

 Specimen from 1006 feet like Lower 

 Gault (W. Hill). Hard, drv, friable [light- 

 grey] clay at 1050 to 1056 feet. Then 

 dark soft clay [grey, with some bits of 

 a lighter colour], impeding the progress 

 of the pipes. Ammonites splendens at 

 1170 feet, when the clay becomes harder. 

 Inoceramus sidcatus at 1170 and 1179 

 feet (E. T. Newton). Phosphatic nodules 



from 1171 feet 



Brown and dark- greenish sandy clay. Sand 

 only observed near the base. At the base 



[_ a layer of phosphatic nodules 



Lower Greensand. Fine, sharp, light-brown sand, of 

 the ordinary character of that in the Folkestone 

 Beds. With water 



Thickness. 

 Ft. In. 



31 



Depth. 

 Ft. In. 



970 



260 



1230 







4 



1234 







9 



1243 







Remarks on the Geological Divisions. 



The basement-bed of the London Clay being well marked, so also 

 is the amount of that formation and the thickness of the Heading 

 Beds. The latter agrees with what is shown by various other well- 

 sections in the neighbourhood, in which the thickness of this form- 

 ation varies from about 70 to over 90 feet, except for Slough, where 

 it falls to a much lower figure. 1 



There is some doubt as to the position of the Chalk Rock, and it 

 may be that it is the bed below that suggested which ought to be 

 so classed. Of course, therefore, the division between the Upper and 

 the Middle Chalk is somewhat doubtful. 



1 See Geol. Surv. Mem. 1889, ' The Geology of London and of Part of the 

 Thames Valley,' vol. ii. pp. 3-10, 334, 335. 



