The East Anglia Region - Southern England - page 308

Cretaceous Chalk. This tells us that since the Anglian cold spell, the river has firstly
formed meanders by side-cutting and only later cut downwards to produce its valley.
Although much redeveloped, it is still possible to see many features of medieval
Norwich in Figure 309. To the left, the River Wensum flows generally southeast, and
its first large meander became the site of the cathedral (with the spire) and the castle
(on the obvious mound to the right). The River Wensum formed the early northern
boundary of the city, which was surrounded on the other three sides by curtain walls
that still exist in some areas.
FIG 309. Medieval centre of Norwich (Fig. 294, c10 ). (Copyright Aerofilms)
The location of Norwich represents a balance between the relative ease of
bridging rivers where they are smaller above a confluence, and the advantage of being
able to bring cargo further up a river when it is still tidal.
Norwich Castle and museum perch above the medieval city centre, and when the
shopping centre was built nearby the excavations penetrated deeply into the Chalk.
Elsewhere under Norwich, tunnels have been dug to extract chalk (for lime) and flint
(also for building), as well as to create storage. These tunnels are prone to collapse and,
in one incident a few years ago, trapped a double-decker bus.
Early work on Norwich Cathedral was began late in the eleventh century. It is situ-
ated lower than the castle, close to the valley floor but on a terrace of old gravels. The
lack of good building stone in the north and east of East Anglia means that the stone
for the cathedral was brought over from Caen in France. Barges carried the blocks via
the English Channel and the North Sea to Great Yarmouth, then up the rivers Yare and
Wensum to a short length of canal that ran to the cathedral.
For most of their courses, the rivers of Norwich have wide valleys with sides that
are relatively low (often less than 20 m) and gentle. One exception is the slope where