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Book II. Chap. II. Beds bclicecn (he
subordinate beds of ochre cover the Aylesbury limestone bedson the summit of Shotover hill, which forms a correspondingelevated group to that of Brill, over against which it stands;and it may be traced hence throughout the southern vale, asthe dark red soil, prevalent on the road to Tetsworth, at onceindicates to the eye.
On the opposite side of the Thames, the system of hills ofwhich Shotover forms a part, is continued through the northof Berkshire by the range of which Cumnor hurst forms thehighest point on the east, and Faringdon clump on the west.Both these summits are capped by the iron sand, but it hasbeen denuded off from a great part of the intervening ridge,and occurs in these points only in the form of insulated andoutlying groups. The main course of the formation lies throughthe southern valley, but is mostly concealed by alluvia fromthe overhanging ranges of chalky downs.
In Wiltshire , we are informed by Mr. Townshend, that thissand occurs at the foot of Beacon hill in the road from Pewseyto Chippenham , and may thence be traced rising up all theway to Lockswell heath and Dring hill. That it also emergesfrom beneath the clay at Foxhanger, west of Devizes , andthence rises up to Seend. It is here described as being apudding-stone, composed of rounded quartz, whose cement issiliceous with a red calx of iron, containing ore formerly inmuch request for the furnace and the forge, and forming thematerial whence the ancient Britons wrought their Quernstones.
It seems probable that in proceeding farther west, this for-mation thins out and expires, since we do not meet with anytraces of it in the west of Dorsetshire ; but in the south-east ofthat county it is very strikingly displayed throughout the Isleof Purbeck, where it consists of many beds of quartzose con-glomerate, and of coarse and fine-grained sandstones containingseams of wood coal. It here forms a narrow stripe (the highinclination of its strata reducing the space they occupy in theirsuperficial appearance) running parallel to the chalky downs,and along their southern foot.
In the Isle of Wight it forms the substratum of all thesouthern half of the island ; cliffs of it may be traced fromSandown bay on the east to Freshwater bay on the west, ex-cepting w here concealed by the subsided ruins of the under-cliff.
In the south-eastern counties, this formation constitutes thecentral chain of hills which traverses the Weald of Sussex fromHastings to Horsham, and sends off several branches, one ofwhich extends to Tunbridge Wells . It is separated on the