England's Historic Seascapes: Southwold to Clacton
Oxford Archaeology (South), 2007. https://doi.org/10.5284/1000277. How to cite using this DOI
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Resource identifiers
- ADS Collection: 746
- ALSF Project Number: 4729
- DOI:https://doi.org/10.5284/1000277
- How to cite using this DOI
England's Historic Seascapes:
Southwold to Clacton
ALSF Project Number 4729
Oxford Archaeology, 2007
Black Deep and Long Sand
Primary Subcharacter Type:
Channel
Main Character / current form and use
This area is one of several pairings of sandbank and channel off the North Essex coast which form a series of treacherous navigational features and hazards in one of the major approaches to the Thames. The pairings are considered together due to the dynamic nature of sandbanks. The predominant characteristic of the area is its function as the main deep water route into the Port of London from the North East with associated hazards. The majority of the character area also falls within the Port of London and Haven Ports pilot boarding area.
The Black Deep Channel has a minimum depth of 14m and is used by bulk carriers up to 14.1 m draft. Passage through Black Deep is normally restricted to vessels with a draught of over 6 m unless access to the Princes channel is restricted (UKHO 2006b) Other shipping known to use the route include merchant shipping, tankers and ferries. Leisure sailing routes are found in the character area, which is also a potential recreational dive site.
Long Sand and Long Sand Head are located to the south-east of Black Deep and are recognised ship wreckers. Overall the depth in the area is in the region of 2-20 m, but this declines sharply to 2-5m over Long Sand. Recent surveys have shown that Long Sand is steadily migrating south-east whilst Long Sand Head is extending in a north-east direction in what may be interconnected processes (UKHO 2006a). Areas of the bank are covered with megaripples and sandwaves which can be hazardous for shipping.
The geology is predominantly gravelly muddy sand with patches of gravel in the deeper areas. The tidal range in the character area is mainly within the range of 4-5 m at Mean Spring Tide (DTI 2004). Long Sand acts as a barrier between the Dover tide to the south and the North Sea tide to the northeast. As a result water levels can be at different levels on either side of the bank at any time (D'Olier 2002).
The character of the area may change in light of the forthcoming London Gateway Project - a proposed redevelopment of the former Shell Haven Refinery on the north side of the Thames Estuary. The increased size of shipping expected at the new terminal may lead to dredging in Black Deep (UKHO 2006b). The area also incorporates a small part of the London Array windfarm site (see Kentish Knock and Knock Deep) which may alter its character.
Historic Character and archaeological potential
The admiralty chart of 1855 shows both Black Deep and the Long Sand shoals as navigational features and it is likely that these have long been recognised as such. Nelson is reputed to have said that in terms of navigation the Thames Estuary is one of the worst areas around the UK, being as tricky as a tiger (Bowskill 1998, 159). Records indicate that ships tended to be caught out by Long Sand including the Indian Chief grounded in 1881 and the Hawksdale in 1899 (Jarvis 1990). Overall, 31 known wrecks are located within the character area, though many were mined or torpedoed indicating the area was heavily mined in both World Wars as an important shipping route. These include HMS Coquette lost in WW1 and HMS Velia presumed mined in WW2. Other named vessels include coastal and continental traders. Notably the wrecks are distributed around the shoals of Long Sand and Long Sand Head. In total 19 of the wrecks are considered dangerous and 11 foul ground.
The Albert Close fishing chart of 1953 records that this area was good sole ground in the summer.
In addition to the high archaeological potential in relation to shipwrecks, the area has potential to contain submerged prehistoric landscapes, features or artefacts, having been dry land prior to 8000 BP. However, no investigation work is known to have been done in this area.
Character perceptions
The character area of Black Deep and Long Sand is a region heavily used by bulk shipping traffic, though navigational hazards are key to its use. It is unlikely that the London Gateway redevelopment will greatly alter the character of the area, though it may result in dredging, use by heavier shipping and re-routing measures.
Bibliography
Bowskill, D. 1998, The East Coasts, A Pilots Guide From the Wash to Ramsgate. Imray, Laurie, Norie & Wilson
D'Olier, Wallingford, B. H. R., 2002, Southern North Sea Sediment Transport Study, Phase 2 (appendix 10). Technical Report. CEFAS/UEA
Jarvis, S., 1990, East Anglia Shipwrecks. Countryside Books
UKHO, January 2006, Thames Estuary Black Deep: Assessment of the Analysis of Routine Resurvey Area TE6A from the 2005 Survey. UKHO
UKHO, March 2006 b, Thames Estuary Long Sand Head: Assessment of the Analysis of Routine Resurvey TE5B from the 2005 Survey.
Wikipedia. Available at: http://en.wikipedia.org (15/03/2007)
