412 Dr. A. Irving—Sections of Bagshot Beds. 
Sands in the lane a little way to the south below Ridge Farm, and 
the position of the whole Middle Bagshot group, on the other side 
of Ninemile Ride (Q.J.G.S. vol. xliv. pp. 171, 172). These facts 
so strongly substantiate the mapping of these California beds as the 
basement-beds of the Middle Bagshot, that their true horizon can 
scarcely be a matter for further discussion.! The 20 feet of clays 
and loams, with included irony nodules, which are here recognized 
as constituting the basement-beds of the Middle Bagshot, seem to 
mark the most persistent and constant horizon through the whole 
Bagshot district ; they are as distinctly recognizable at their southern 
outcrop at Aldershot, Ash and Woking, as they are on this northern 
side.* In every case where they do not overlap the Lower Bagshot, 
and rest directly upon the London Clay, they are succeeded down- 
wards by a fine quartz sand, generally containing minute flakes of 
glassy silica. In most of the well!-sections known to me on the northern 
side of the district, this is a dirty carbonaceous sand, generally 
blackish with a tinge more or less of green, and it usually contains 
lignite and pyritous material, the latter often cementing the sand 
into hard nodules. On the other hand, where it crops out at the 
surface, it occurs as a much cleaner sand (in places almost a ‘silver 
sand’), from long exposure to the oxydizing action of atmospheric 
waters. This succession, which is seen in the wells at California 
(see section), is seen in the banks of King’s Mere, and near the 
railway about three-quarters of a mile to the east ; it occurs again 
in the valley three-quarters of a mile north of Wellington College, 
where I have lately proved the base of these loam and clay beds of 
the Middle Group by excavation ; at exactly the same altitude (216 
0.D.); it isseen at Wokingham, in the railway-cuttings at Buckhurst 
and Bracknell, in the Pinewood Brickyard by the Ninemile Ride 
(14 miles east of California) ; it was proved in a well at Longmoor, 
about a mile to the west, some years ago, and in a well at the village 
school, Finchampstead, which was dug two years ago. At the western 
end of Finchampstead Ridges we can trace the succession of the beds 
by a number of road-sections, from a section in the Upper Bagshot 
at North Court (800 o.p.)? down through the pebble-bed (at about 
1Q.J.G.S. vol. xli. p. 504; also cdid. vol. xlii. p. 408. There is, moreover, 
nothing in the known structure of the Lower Bagshot Beds of the deep-well sections 
of this northern side of the district to warrant the assignment of those beds to that 
group. 
ee fihleve traced and mapped for the most part their outcrop along the northern 
flank of the Bagshot area from Farley Hill south of Reading to Englefield Green 
(see last paper, Q.J.G.S. May, 1888). 
3 Recently a new road-cutting 8 to 10 feet deep, close by North Court, has 
given us a capital section of the Upper Bagshot Beds. The beds are of the usual 
character in the lower part of the section, but these pass upwards by a steady 
gradation into a very stiff irony ‘leathery’ loam, in which occur numerous pipes and 
small layers of loose sand intermingled with many black and some green grains. 
They are infillings in all probability of the holes and tubes left by the decay of the 
roots and rhizomes of plants that grew im sitw, when, after the close of the Bagshot 
period, the ancient marine estuary became reconverted by an ordinary silting-up 
process into land. Emptied of the contained sand, these holes and tubes bear a 
striking resemblance to those often seen in Sarsen stones (cf. remarks by the author, 
Proc. Geol. Assoc. vol. vill. p. 155). 
