Monument MPM1195 - Remains of Former Town Defences, Portsmouth City Museum

Evidence of the former 17th and 18th century town defences was revealed during a watching brief at the City Museum & Records Office site in 2009. Deposits relating to the defensive earthworks and outworks of the fortifications were observed, including the moat, glacis and covered way. There were also a number of deposits associated with the demolition and levelling of the defences.

The museum site lies within the area of the former East Bastion and moat. The Old Records Office building is situated partly within the area of outworks of the former East Bastion, and the western end of the building lies within the former line of the moat. The defences were demolished during the 1860s and 1870s.

Features and deposits recorded during the watching brief:

A cut (10) for the defensive works, including the moat and levelling of the covered way, was observed across the entire site. It was c5.8m and c4.2m below the surface in boreholes in the north of the site, where it was located within the area of the covered way, and c5m below the surface in the south. The difference in the levels may be due to the sides of the moat being sloped.

The earliest deposit (9) recorded on the site related to the defensive earthworks and the moat. When observed in boreholes in the north of the site, this was probably part of the raised earthwork forming the glacis, counterscarp and covered way. The same deposit was observed in boreholes along the eastern side of the site - where it appeared to be the primary fill of the moat - and was probably made up of material from the demolished earthwork.

Two limestone and mortar deposits (22 & 25) were revealed in boreholes in the north and south of the site. The deposit in the north (25) was 2.7m below the ground surface and 600mm thick. This may have been part of the revertment at the north side of the moat, or alternatively, it could possibly have been part of the late 17th century outworks of the East Bastion designed by De Gomme. The deposit in the south of the site (22) was 4m below the ground surface and around 1m thick. This possibly represented the remains of the revetment at the rear of the counterscarp of the East Bastion.

A number of deposits associated with the demolition of the defences and the levelling of the earthworks were observed in both the north and the south of the site. These mainly consisted of a stony sandy clay loam, which contained fragments of brick, charcoal, and tile.

The construction trench for the Old Records Office building was also observed in the test pits. This was over 1.7m deep and cut two of the deposits relating to the demolition and levelling of the earthworks. It was filled with a concrete and brick foundation.

Two walls observed in a test pit in the south of the site possibly related to an out building which formerly stood on the site, and a layer of brick rubble may have been associated with its demolition.

[1]

Accession number: 2009/13

<1> Cottrell, P R & McDonald, E L, 2010, Archaeological Watching Brief at Portsmouth City Museum, Museum Road, Portsmouth (Unpublished document). SPM169.