Event/Activity EPM222 - Watching Brief at the New Mary Rose Museum, Portsmouth Historic Dockyard, Portsmouth, Hampshire

An archaeological watching brief was carried out by Pre-Construct Archaeology between the 30th September and 7th October 2009 on works associated with the new Mary Rose Museum in Portsmouth Historic Dockyard. Archaeological monitoring took place on the excavation of service trenches for temporary toilets and welfare facilities, and the excavation of postholes for a hoarding to surround the 20th century Trafalgar Building during its demolition. The trenches and postholes were excavated by hand. A total of 38 main postholes were excavated approximately 1.80m apart, 25 on the south side of the Trafalgar Building and 13 on the west. The last few postholes were not monitored, as the other holes had not produced any significant archaeological material. The postholes measured 0.70m x 0.70m x 0.40m deep. Each of the postholes had a smaller 'backstay' hole for a diagonal brace which also measured 0.70m x 0.70m 0.40m deep. Historic granite setts disturbed by the work on the west side of the Trafalgar Building were excavated and palleted for storage and re-use in landscaping for the new museum. A total of three service trenches were excavated. Trench 1 was located parallel to the eastern side of the Trafalgar Building, and Trenches 2 and 3 were excavated to the northeast of Dry Dock 4. The postholes revealed that significant landscaping is likely to have occurred around the Trafalgar Building and Victory Arena during the 20th century. Granite cobble setts re-laid in concrete were observed beneath the modern tarmac surface on the west side of the Trafalgar Building. At the western end of the south face of the Trafalgar Building, the re-set cobbles overlay levels of ground raising. Intermittent elements of red brick walls and floor surfaces abutted redeposited cobbles. The re-set cobbles and the walls and floors are thought to have dated to a phase of 20th century landscaping and remodelling of the yard. Trench 1 measured approximately 24.2m in length by 0.30m wide and 0.30m deep. Re-set granite cobbles were removed from the northern part of the trench and stored for reuse. A spur was excavated at the southern part of the trench, measuring 0.30m wide by 0.20m deep. The lowest horizon within this section of trench was a layer of loose crushed brick ground raising which had been sealed by tarmac. The remains of an in-situ granite floor were also observed, although much of this feature had been removed by the excavation of a manhole. Trench 2 measured approximately 13m in length by 0.40m wide and ran parallel north-south with Main Road. Re-set granite cobbles set in modern concrete were observed below the modern tarmac in various sections of the trench, and the lowest horizon was a layer of modern made ground approximately 0.50m below the ground surface, which probably represented backfill from a service trench. The trench was divided in two by a pair of railway tracks set in modern concrete on a southwest to northwest alignment which appeared to enter a promontory between Dry Docks 4 and 5. A tunnel for the service pipe was made through the concrete foundations. Modern concrete in the northern half of the trench had been truncated by modern services. Trench 3 was aligned east-west and formed a 'T' shape with Trench 2. It measured approximately 12.50m in length and was approximately 0.20m deep at its western end and 0.44m deep at its eastern end. Patches of re-set granite cobbles were observed below the tarmac. The top of a wooden pile or post was observed, although not fully exposed. This may have related to the construction of the docks. Several sets of railway tracks were recorded where the trench crossed main road. One appeared to be the same set observed in Trench 2. Two additional sets were a narrower gauge and were set into indurated concrete. They extended parallel with the western side of Main Road. It was concluded that the postholes and service trenches were not excavated deep enough to enter into pre-20th century archaeological horizons. The only exception to this was the timber pile which may have related to the construction of Dry Dock 4. 20th century landscaping and the addition of railway tracks between Dry Docks 4 and 5 had raised ground heights significantly. Accession No: 2017/71