RSK is providing archaeological, geotechnical, soils testing and remediation expertise to the Mersey Gateway project, a high-profile project that involves the construction of a six-lane toll bridge over the River Mersey between Runcorn and Widnes. Scheduled to open in 2017, the new bridge will relieve congestion on the ageing Silver Jubilee Bridge, which has been the key crossing point for the river since 1961.
Archaeology and cultural heritage are vital parts of the land development process. RSK’s contribution to projects such as the Mersey Gateway provides the high-quality professional archaeological consultancy services that clients need while complying with heritage sector regulations, best practice, standards and guidance.
During excavations for the new bridge piers in salt marshes at Widnes, the RSK archaeology team discovered oak timbers and red deer bones overlying glacial clay at the bottom of the estuary sediment. The objects were in a layer of sediment 11 m below the current land surface and subsamples were sent for dendrochronological analysis (tree ring dating) and radiocarbon dating.
The timbers proved to be from the Late Mesolithic period (approximately 4500–4200 BC). A large oak tree trunk found about 2 m higher in the sediment column was dated to the Late Neolithic period (approximately 2800–2500 BC).
These findings have helped to reveal the environmental changes that have occurred in the area and provided fresh insights into a submerged post-glacial landscape, as Laurence Hayes, RSK principal archaeologist, explains. “At the end of the last ice age, there was a gradual rise in sea level that inundated the Mersey Valley. Before this happened, the landscape would have been mixed deciduous woodland providing a habitat for red deer and other animals, and a hunting ground for the local hunter-gatherer populations. Over the following millennia, estuary sediment accumulated to a depth of 11 m thereby sealing and permanently waterlogging the fragile organic remains that we have found and preserving them in perfect condition.”
For more information about the archaeology and cultural heritage work RSK is conducting on the Mersey Gateway project, please contact Laurence Hayes