By G. Poulett Scrope, Esq., M.P. 105 
_ Next in order of succession proceeding eastwards, we find a 
purely marine formation of sands and sandstone, which from con- 
taining many Chloritic particles, giving it, occasionally, a dirty 
yellow or greenish colour, has been called the Lower Green sand, 
and is now often styled the Neocomian, from its large development 
at Neuchatel, in Switzerland. It underlies another thick band of 
marly clay, called Gault, which is separated from the chalk above 
it by other sandy beds, to which the name of Upper Green sand 
is given. These several formations, with the chalk, compose the 
Cretaceous group of the Geological Survey. 
In some parts of South Wiltshire, especially alone the north side 
of the Vale of Wardour, the Upper Green sand, owing, probably, 
to the hard cherty character of some of its beds, rises into a ridgy 
range of hilly eminences, projecting themselves in front of, and 
parallel to the chalk escarpment behind. One of these at Stour- 
head, on the summit of which Alfred’s tower is built, reaches an 
elevation of above 800 feet above the sea. In North Wiltshire this 
formation occupies a slightly prominent step or terrace below the foot 
of the chalk hills. Both the Upper and Lower Green sands are re- 
markably rich in fossils, and especially in Aleyonites and otherspong- 
iform Zoophytes. The fine collection formed, chiefly from these strata, 
by the late Miss Ethelred Benett, (now dispersed) was well known 
to geologists; as is also that belonging to our excellent Secretary, 
Mr. Cunnington, at Devizes. Almost the entire Vales of Pewsey and 
of Wardour, which penetrate far into the chalk platform, as well 
as that smaller indentation about Warminster and the Deverills 
running up the Vale of the Wily to Norton, are hollowed out of 
the Upper Green sand. Overlapping these sandy beds rise the. 
steep slopes of the chalk hills, which compose, as has been already 
said, the eastern half of our county, and reach, in the instances of 
Hackpen, St. Anne’s Hill, and Martin’s Hill among the Marl- 
borough Downs, to an elevation exceeding 1000 feet above the sea. 
The lower beds of chalk are generally marly, from containing 
clay, and often form a sort of lower terrace at the foot of the chalk 
slopes. The upper and thicker chalk consists of that pure white 
calcareous mass, so well known to most Wiltshire-men, usually too 
