By Professor T. Rupert Jones, F.RS., F.G.8., Fe, 183 
more above the Reading Beds still undisturbed below. In Kent, 
Middlesex, and Hertfordshire the Woolwich-and-Reading Beds were 
the more prolific source of these blocks. 
Doubtless many blocks were forcibly moved away from their 
parent beds and knocked about as the strata were denuded at their 
edges by encroaching waters, but where the stones lie flat over wide 
areas, or have been arranged in an orderly manner in superficial 
hollows with brick-earth made out of the beds themselves, doubtless 
they were “quietly let down during the slow denudation and re- 
moval of the softer material of the beds of which they once formed 
apart.” Whitaker, Geol. Mem., Explan. Sheet 7, p. 72. 
In the gravel on Crawley or Portisbury Hill, above Camberley, a 
spur of the Frimley Ridges, very fresh Sarsens are met with. The 
Upper Bagshot Sand has here been denuded and replaced with the 
high-level ferruginous flint gravel; and in this the Sarsens lie, their 
-mother-sand having been removed from above and around them, 
but still almost in contact with their convex lower face. 
Sarsens are very often found in the patches and pockets of sand, 
brick-earth, and gravel on the Chalk,’ and usually are then much 
eroded and worn. These materials are the remnants of Tertiary Beds 
once lying, perhaps thick, on the Chalk, together with some of the 
flint of the denuded Chalk itself. On Barbury Down (and probably 
elsewhere) occasionally a green-coated flint, peculiar to the lowest 
stratum of the Woolwich-and-Reading Beds, may be picked up, 
showing that these beds contributed some of the alluvial spoil of 
that region, and possibly, as far as they reached, some of the Sarsens. 
1 Near Wycombe, Nobles, Napple Common, Walter’s Ash, Denman Hill, 
Bryant’s Bottom, Hampden Row, &c., also in the Marlborough Railway-cutting, 
at Inkpen, and many other places. Sarsens are particularly abundant in the 
gravel of the Kennet Valley, near Newbury. 
Dr. Joseph Stevens, in his papers ‘‘ on Sarsens, Greywethers, Druid Stones,” 
read before the Winchester and Brighton Natural History Societies in 1874 (see 
the bibliographic list), after noting the distribution, origin, and structure of 
these sandstone blocks, considers their drifting, or removal from the original 
sands, to have been coeval with the formation of the Brick-earth on the high 
Chalk tracts, which is inferred to have been deposited at the close of the Glacial 
Period. Geolog. Record, vol. i., p. 35, and vol. ii., p. 37. 
