Floating Landing Stages, Cambridgeshire Geoarchaeological Watching Brief Report:

In October 2011 Oxford Archaeology undertook a Watching Brief on geotechnical
boreholes associated with the creation of series of new floating landing stages
adjacent to seven locks across Cambridgeshire and Norfolk. The scheme aimed to
provide new or replace existing landing stages for users of the waterways to safely
moor whilst using the locks.
The drilling of 7 boreholes were monitored across three main sites: Water Newton,
Downham Market, and Earith. The purpose of the Watching Brief was to provide
base-line data regarding the character, extent and archaeological potential of the
alluvial and peat stratigraphy that may be effected by the Scheme. The borehole
samples were examined for signs of archaeological indicators and were subsampled
for further sedimentary analysis and radiocarbon dating.
Despite the sites being located near to areas which have previously produced
significant prehistoric, Roman and Medieval archaeology, no archaeological
deposits were identified within the boreholes sequences.
A series of boreholes were taken through the base of the modern river beds
revealing that the Fenland sequence has been significantly truncated or removed in
these locations. Prehistoric Fen peat deposits was only found to be preserved along
the river banks at the Earith and Downham Market sites. These sequences have the
potential to preserve import early prehistoric remains and contain a sequence of
environmental and hydrological change that spans the Holocene. The surface of
these peats are preserved at depths of 5.25m bg (-1.25m OD) at Salter Lodge,
4.65m bgl (+0.15m OD) at Denver Lock, 3.6m bgl (-0.9m OD) at the Old Bedford
Sluice and 4.45m bgl (+1.95m OD) at Hermitage Lock. The peat sequences
accumulated from the early Bronze Age into the late Roman period.
Two of the sequences provided indirect evidence of archaeological potential, in the
form of buried soils at Water Newton (BH01) and Downham Market (BH04). In the
former, an early Mesolithic landsurface was found sealed underneath a lower peat
overlain by channel deposits. A later buried alluvial soil containing charcoal was also
identified within OABH4 underlying post-medieval made-ground deposits, possibly
associated with the digging of the Old and New Bedford rivers.
The main impact of the proposed Scheme will be predominantly from piled
structures in the base of the modern riverbeds. Only at Salter's Lode, Old Bedford
Sluice and Hermitage Lock will adjustments be made to the river banks to aid site
access. The bank-side modifications are to be confined to a depth of 1m and will
leave the identified buried surfaces and Nordelph peat sequence unaffected by
these works.