By G. Poulett Scrope, Esq., M.P. 97 
tion of the high chalk platform, which constitutes also the greater 
part of Hampshire, and sends out four several embranchments, one 
to the south into Dorsetshire, another to the north-east into Berks 
and Oxfordshire, and two towards the east, which form respectively 
the ‘north and south downs,’ by which the intermediate vale country 
of the Weald of Kent and Sussex is, as it were, embraced. The 
Wiltshire part of this great chalk platform is penetrated by three 
wedge-shaped depressions or valleys, having their broader open- 
ings to the west, and gradually narrowing to an acute angle towards 
the east; viz., the Vale of Pewsey, which divides what are 
usually called the Marlborough Downs from those of Salisbury 
Plain, and those of Warminster and of Wardour. ‘To the north 
the chalk hills overlook the still broader Vale of Swindon, con- 
tinued to the east in that of the White Horse, to the south-west 
in that of the western Avon. All these vales, of course, occupy 
generally far lower levels than the chalk district, and consist of 
strata of earlier formation which ‘ crop out,’ as it is called, one 
from beneath the other as we travel to the west or north from the 
chalk escarpments. Whether the chalk ever extended continuously 
over the whole of these vales, may be disputed, but, without doubt, 
it did over a considerable portion of their area, and has since be- 
come removed by denudation, that is, by the wash and sweep of 
water, probably in part that of ocean currents before or during 
the rise of this area of the island from below the sea, partly of the 
rain to which it has been exposed ever since. And the ‘detritus’ 
or fragmentary matter carried away from these excavations went 
to form those beds of flint gravel, tertiary and post-tertiary, which 
we find strewed over the hills and almost filling the valleys of the 
Avon, the Thames, and other rivers in the East of England. 
The strata exposed in the Vales of Pewsey and Wardour chiefly 
belong to the Upper Green sand, which also shews itself through 
‘the entire width of the upper Vale of the Wily, between War- 
minster and Maiden Bradley. The great northern vale is more 
varied in its composition, the several beds of the oolitic series crop- 
ping out successively from beneath the Cretaceous group, and 
shewing themselves through its whole length from Shrivenham 
H 
