Source/Archive record SCH8885 - Northgate Steps, City Walls, Chester: Further Archaeological Watching Brief

Earthworks Archaeology Ltd. was commissioned by Cheshire West & Chester Council to undertake an archaeological watching brief and, where necessary, further archaeological investigations during enabling works ahead of the rebuilding of the Northgate Steps, City Walls, Chester (centring on NGR SJ 40400 66668). The walls, towers, gates and posterns of the city are listed under the Ancient Monuments and Archaeological Areas Act 1979 (List entry number: 1006785) and are considered of national importance. A watching brief maintained throughout the controlled dismantling of the Steps and elements of the adjacent City Wall between June 2016 and April 2018 (see ECH6654; R4271/SCH8626) revealed structural remains relating to the defences of the Roman legionary fortress of Deva (Chester), including a section of the earthen rampart, a single large posthole which may relate to a timber gatehouse structure, also the remains of two substantial, sandstone block walls, interpreted as possibe foundation courses for a later Roman masonry gatehouse. Prior to the rebuilding of the Steps and City Wall, further archaeological work on these remains was deemed necessary and this report summarises the results of a watching brief carried out between September 2019 and April 2020. Whereas the masonry remains of the Roman north gate (porta decumana) were to be preserved in situ during the planned rebuilding of the Steps structure, elements of the earthen defences and core material at the base of the City Wall would require controlled removal as part of the rebuild enabling works, including the laying of stone mats for the insertion of concrete piles, foundation slabs and underpinning necessary for the structural support of the Steps and City Wall. Full excavation of the large rock-cut posthole demonstrated that this could have accommodated a squared timber post perhaps as large as 0.60m square, twice that of the standard 0.30m square post size considered standard for the east and west gateways of the extensively excavated legionary fortress at Inchtuthil, Scotland. One side of the posthole was sloped to allow insertion and placement of the timber post prior to erection, the postholes encountered at Inchtuthil were similarly prepared. Reduction of the rampart material confirmed individual blocks of earth similar to that recorded elsewhere along the primary defences. The samples taken from the rampart demonstrated that the base of this material had been laid directly upon the weathered surface of the sandstone bedrock and that no former ground surface survived in this area. To the west of the North Gate, the evidence encountered during the excavation of stone rubble core material beneath the City Wall has demonstrated that the upper deposit of rubble is of post-medieval date, below this the rubble core is Roman in date. Furthermore, the stratigraphic level at which the these deposits meet coincides with the level of the large and in situ blocks of masonry interpreted as belonging to the Roman revetment wall of the masonry gate tower.