EDO3903 - Colliton Street Youth Centre, Dorchester; Evaluation Trench 1

Wessex Archaeology undertook an archaeological field evaluation at Colliton Street Youth Centre in advance of the proposed redevelopment of the site. The evaluation comprised four machine-dug trenches, totalling 20m in length and averaging 1.7m wide (totalling 2.3% of the site area). Chalk bedrock was recorded in the base of all four trenches and a natural drop of 2.19m was recorded from the south to the north of the site. Trench 1 was approximately 9.5m long, aligned approximately NE-SW, and located in the NW corner of the site. The trench was excavated down to the top of chalk bedrock which was encountered at a depth of 69.09m OD. Two substantial ditches were cut into the chalk bedrock, both aligned approximately northwest to southeast, at least 3 m wide and the more westerly ditch was at least 2 m deep below the top of the chalk bedrock. No dating evidence was recovered from either ditch, although their alignment and dimensions suggest they were part of the defensive ditch system of the medieval castle of Dorchester. A N-S aligned wall lay above the fill of the westernmost ditch, possibly of post-medieval date.