The question has arisen on Facebook as to why old photos of Dover beach show the beach to extend much further up the seawall today than it did prior to construction of the Admiralty Harbour. After much head scratching I have come to the following conclusion which may be right or may be wrong.
This is a Hydrographic survey of Dover Harbour in 1844 showing the extent of the beach immediately prior to commencement of construction of the Admiralty Pier in 1847. The seafront buildings have been erected on the shingle bank which had accumulated to the East of the harbour entrance due to longshore drift. This had plagued Dover for centuries, continually blocking the harbour entrance. By 1850 the Admiralty Pier had extended far enough out into the tidal stream to deflect the longshore drift past Dover and had finally put an end to this perennial problem.
This modern day bathymetry chart demonstrates the changed situation following completion of the Admiralty Harbour comprising the Admiralty Pier and extension, the Southern Breakwater and the Eastern Arm. The jetstreams which pour through the entrances in the hours leading up to high water bring in enormous quantities of silt which are distributed around the harbour by the circulating currents. Deep water is maintained in the Outer Harbour and around the cruise ship and ferry berths by constant dredging, leaving the shelf depicted in brown and yellow on the chart.
I believe this shelf to be the reason that the beach level is so much higher up the seafront wall than is seen in photos prior to the construction of the Admiralty Harbour. The line of the shelf may also be the reason for the clear defining line in the water that Paul B has observed at various times from Boland Towers.
Charts copyright Port of Dover Tidal Atlas 3rd Edn 1999 with permission.
