Service Diversion North of Woolwich Portal, Albert Road, Factory Road (Crossrail XSV11)

Abstract

• A general watching brief was undertaken by MOLA at the North Woolwich Portal worksite which consisted of utilities diversions centred around Albert Road and Factory Road. This work was undertaken as part of a wider programme of assessment to quantify the archaeological implications of railway development proposals along the Crossrail route. The North Woolwich portal site lies within an Archaeological Priority Area. There are no scheduled monuments or listed buildings within the site. Underlying the tarmac surface, modern make-up varied in depth from 0.70m to 2.5m below ground level. Generally, trenches excavated to a depth of 2.0m and deeper revealed alluvial soils under modern made ground and tarmac. No archaeological remains were exposed within the shallow sequences. A minerogenic alluvium and peat sequence was recorded beneath modern made ground and tarmac in the deeper trenches which were excavated to a depth of c3.0-4.0m below ground level. The potential for palaeoenvironmental and topographic evidence within the alluvium and peat sequence was moderate to high. However, fieldwork has demonstrated that little archaeology remains within the deeper alluvial sequences. Timbers preserved within the peat deposits were of no archaeological significance, representing driftwood preserved within the marginal wetland. No archaeological structures or associated features indicative of human occupation were observed. At the western end of Factory road, by the Tate and Lyle Sugar Factory, a series of levelling and dump deposits were revealed within the upper made ground to a maximum depth of 2.0m below ground level. These are likely to represent the foundations for the construction of the North London line railway established here in 1847. Natural geology was not exposed. Four trial trenches and a targeted watching brief on the eastern half of the portal enabled recording of the alluvial sequence above the natural Pleistocene Thames gravels. A meandering river of potentially early Holocene date, interspersed with higher sand and gravel floodplain on which Mesolithic activity took place. Flint scatters were observed in three trenches indicating that the shoreline environment was used by people from this period onwards. By the time of the Mesolithic\Neolithic transition, peat had formed above the sand and gravel before rising sea levels in the Roman or later periods inundated the area to deposit alluvium in an estuarine floodplain. The results of the three evaluation boreholes when used to update previous deposit modelling broadly confirm anticipated findings. High areas of Pleistocene gravels and early Holocene sand form dry land islands with a low lying channel floodplain. These dry island areas have the potential for Mesolithic activity. Channel routes migrated and silted up in these deeper channel areas during the early Holocene. Subsequently, river levels continued to rise over the Late Mesolithic to Bronze Age, resulting in transgression and regression episodes, which waterlogged these drier island areas allowing for dense wetland vegetation to develop. As further inundation occurred, thick clay alluvial deposits formed, levelling out the terrain, with any former depressions in the flood plain area silting up. Woodland became increasingly waterlogged and died off, and the landscape would have become much more open. Because of the potential for Mesolithic archaeology, related to hunter-gatherer-fisher activities centred on the gravel island and exploiting the nearby resource rich wetland of the channel marginal zones, and for associated deep organic sequences preserving significant palaeoenvironmental data concerning the development of the River Thames in east London, the results from North Woolwich Portal are assessed as being of regional significance.