Monument record TYY 046 - Post Medieval seabanks in Trimley St Mary and Trimley St Martin

A system of Post Medieval seabanks is visible an earthwork in Trimley St Mary and Trimley St Martin parishes on aerial photographs taken from 1944 onwards. The current seabank, as marked on the modern base map, runs along the edge of the Orwell for roughly 3.3km from TM 26783475, northwards, to TM 25533701. This seabank was constructed in the Post Medieval period as it is depicted on the 1st Edition 25" Ordnance Survey map of circa 1884. (S1) A relict seabank is also visible to the east of the current seabank, running across Trimley Marshes towards Painter's Wood. The exact relationship of this bank to the modern seabank is unclear, but it runs from TM 26663583, south-west from Painter's Wood, across the marshes to TM 26203528 where it splits into two, one branch running southwards to merge with the current seabank at TM 26543485 and the other branch running in more of a westward direction to TM 25783502, where it appears that it has been truncated by the modern seabank. These seabanks are also depicted on the 1st Edition 25" Ordnance Survey map of circa 1884 (S1) and although the phasing is not clear it is likely that they were constructed at an earlier date than the seabank that is still in use today. (S2) (S3) (S4)