hed. Reading flourishes from its
position on the edge of the London Tertiary Basin, Croydon is a suburb
of London, and Hull, though on the Chalk, derives its importance from
the Humber estuary, which cuts through the Chalk and the Jurassic
belts, to drain the Triassic plain and the Pennine region. The narrow
strip of Greensands appearing from beneath the Chalk escarpment on its
northern side is crowded with small towns and villages on account of
the plentiful water-supply. The distinction between the low grounds of
the Jurassic belt and the Chalk country is not always very apparent on
the surface, and from the historic point of view it is important to
recognize the individuality of the Eastern plain which extends from
the Vale of York across the Humber and the Wash into Essex. The
Eastern plain thus includes a portion of the Triassic plain in the
north, a portion of the Jurassic and Chalk belts in the middle, and a
portion of the Tertiary plain of the London Basin in the south.

_The Fenland._--The continuity of the belts of Chalk and of the Middle
and Upper Oolites in the Eastern Plain is broken by the shallow
depression of the Wash and the Fenland. The Fenland comprises a strip
of Norfolk, a considerable part of Cambridgeshire, and the Holland
district of Lincoln. Formerly a great inlet with vague borders of
lagoons and marshes, the Fenland has been reclaimed partly by natural
processes, partly by engineering works patiently continued for
centuries. The whole district is flat and low, for the most part
within 15 ft. of sea-level; the seaward edge in many places is below
the level of high tide, and is protected by dykes as in Holland, while
straight canals and ditches carry the sluggish drainage from the land.
The soil is composed for the most part of silt and peat. A few small
elevations of gravel, or of underlying formations, rise above the
level of 25 ft.; these were in former times islands, and now they form
the sites of the infrequent villages. Boston and King's Lynn are
memorials of the maritime importance of the Wash in the days of small
ships. The numerous ancient churches and the cathedrals of Ely and
Peterborough bear witness to the share taken by religious communities
in the reclamation and cultivation of the land.

_The Weald._--The dissection of the great east and west anticline in
the south-east of England has resulted in a remarkable p