The isolated nature of the Dartford Marshes has seen them used for smallpox hospitals, a fireworks factory and even a WW1 airfield. During the Second World War, the marshes were also used to store ammunition for anti-aircraft guns. Enemy aircraft often navigated towards London above the River Thames, flying directly over the marshes, and the waiting defences.
The footpath that traces the edge of the River Darent towards the Thames passes several of these overgrown, derelict concrete structures. Others can be seen in the adjoining fields, but some of these may soon be lost to the Joyce Green Farm aggregate works.
The windowless structures are understood to be WW2 ammunition stores. They are heavily buttressed, but all are now roofless and crumbling. Brambles, nettles and small trees grow where explosive shells were once stored.
Two of the concrete structures have already gone, replaced by ponds and islands. This new habitat is probably designed as a refuge for wildlife displaced by the coming quarrying, which is expected to extract 670,000 tonnes of sand and gravel from the reclaimed marshland here.