A NEOLITHIC FLOOR. 259
this layer was much thinned in places in consequence of drought and
by the rotting of the surface, due to clearing or agriculture, for on this
level the Romans lived."
" I found the remains of a building in one place, surrounded by the
rubbish remaining from a lengthy occupation."
Later he learned that, "Roman relics were found over the whole
area uncovered by the dock excavation and many were of such excellence
that some of the men were enabled to make a goodly harvest by their
sale in London."
A considerable deposit of peat has been found in the filling
of the streams flowing into the Thames at London, and par-
ticularly in the Walbrook.4 This stream, in early Roman times,
had a clear, swift current flowing over a gravelly base. The
early Romans settled on its banks and formed structures on
piles in its bed, where various industrial pursuits were carried
on with the advantages offered by a good stream of water.
Fig. 8.—Mr. Spurrell's diagram of the Thames Alluvium
SHOWING THE PEAT BEDS.
The Romans built their city wall across the bed of this
stream at Moorfields, and were careful to make provision for
the passage of the water by means of culverts During a later
period of the Roman occupation (probably in the 3rd century),
the stream became a sluggish quagmire and the bed filled with
peaty mud The culverts became choked and the hollow
of Moorfields was filled with a swamp which soaked under the
city wall and spread over a large part of Londinium. Although
much of the city was reclaimed from the swamp during later
Roman times, the Walbrook never regained its former condition,
but continued to accumulate peaty mud until late in the Middle
Ages, when its restricted channel was arched over and buried
underground.
As far inland as Braintree, two bands of peat are found in
4 Arch. Jour. lx., pp. 137-235. Archaeologia, Vol. lx., pp. 169-148.