150 NOTES ON ANCIENT DEFENSIVE EARTHWORKS.
strata of East Anglia, nor any reason for supposing that the idea
would not be likely to occur to them, should circumstances make
mounds peculiarly advantageous.
I think there can be little doubt that there was a British
town on the site of Norwich before the building of the Roman
station at Caister, three miles southward. It is true that a
popular rhyme exists, which says :—
" Caister was a city when Norwich was none,
And Norwich was built of Caister stone."
But the Norwich of, and previous to, the Roman occupation
was doubtless built of wood and other perishable materials, and
the Norwich for which the stone of Caister was used was neces-
sarily the city of a period later than the Roman occupation.
And, on the other hand, it is difficult to account for the presence
of the Roman town on the Taus if the site of Norwich remained
unoccupied at the time, the latter being evidently the better from
the Roman point of view. Indeed the distribution of Roman
stations, as a general rule, was mainly influenced by that of
towns already existing.
At Thetford, on the Norfolk and Suffolk border, there
is an immense artificial mound, the centre of massive
defensive earthworks. Thetford appears to have been a
place of much importance in Saxon times. A glance at a geo-
logical map of the district shows that it occupies, as regards the
rivers flowing into the Wash from West Norfolk, a position
somewhat similar to that of Norwich among the streams of East
Norfolk. The Little Ouse, on which Thetford stands, is the
river by which the Danes most easily penetrated into East Anglia
from the Wash. Consequently it is not surprising that both
Norwich and Thetford were much besieged by them. But the
importance of Thetford must have been just as great
in the times of still earlier piratical invaders. And in this case
we find a popular tradition that the Thetford Mound is the
result of the Devil having wiped bis shoes at that spot after
having dug the dyke bearing his name at Newmarket—a tradi-
tion showing that to the people now inhabiting the district it is
prehistoric.1 This gives a very strong presumption that the
Thetford Mound and other earthworks are British, not Saxon.
Some antiquaries suppose Thetford to be the site of the Roman
Sitomagus, while others place it elsewhere.
1 Gentleman's Mag. Library. Archaeology, Part 2, pp. 329-30.