sands and Gault, which lie at the base of the Chalk
escarpment, between that formation and the Oolites. The Chalk occupies
all the remaining portion of the south-east of England, save the
Wealden area, and extends northward as far as Flamborough in
Yorkshire, forming the Yorkshire Wolds, the Lincolnshire Wolds, the
Chiltern Hills, the N. and S. Downs, the Dorsetshire heights and
Salisbury Plain. But in the eastern and southern counties the Chalk is
covered by younger deposits of Tertiary age; the Pliocene Crags of
Norfolk and Suffolk, the Lower London Tertiaries (London Clay,
Woolwich and Reading Beds, &c.) of the London Basin comprising parts
of Essex, Hertfordshire, Middlesex, Bucks and Berks, and northern
Kent. Again, in the Hampshire Basin and Isle of Wight, Eocene and
Oligocene formations rest upon the Chalk.

When we attempt to decipher the physical history of the country from
the complicated record afforded by the stratigraphical palimpsest, we
are checked at the outset by the dearth of information from being able
to picture the geographical condition in the older Palaeozoic periods.
All we can say is, that in those remote times what is now England had
no existence; its site was occupied by seas which were tenanted by
marine invertebrates, long since extinct. As for the boundaries of
these ancient seas, we can say nothing with certainty, but it is of
interest to note the evidence we possess of still older land
conditions, such as we have in the old rocks of Shropshire, &c. In the
Devonian period it is clear that an elevatory movement had set in
towards the north, which gave rise to the formation of inland lakes
and narrow estuaries in which the Old Red Sandstone rocks were formed,
while in the south of England lay the sea with a vigorous coral fauna.
This condition led up to the Carboniferous period, which began with
fairly open sea over the south and north of England, but in the centre
there rose an elevated land mass from which much of the Millstone Grit
was derived; other land lay towards the north. Slowly this sea
shallowed, giving rise to the alternating estuarine marine and
freshwater deposits of the Coal Measures. Continual elevation of the
land brought about the close of the coal-forming period and great
changes ensued. Desert conditions, with confined inland seas, marked
the Permian and Triassic periods. It was about this time that the