Thames Estuary The new airport would be built on a man-made island in the estuary north of Minster-in-Sheppey There is also some discussion about the need for a Lower Thames Crossing in order to alleviate traffic congestion at Dartford. The Thames Estuary is the focal part of the 21st-century toponym, the "Thames Gateway", designated as one of the principal development areas in Southern England. The appellation Greater Thames Estuary applies to the coast and the low-lying lands bordering the estuary itself. These are characterised by the presence of mudflats, low-lying open beaches and salt marshes, namely the North Kent Marshes and the
Canvey Island location of land areas in Ptolemy's ancient work have led modern researchers to question the correlation between Ptolemy's island and contemporary Canvey. MacBean and Johnson, 18th century historians, contend "Counus Island" would have existed much further out to sea (or even likely to be the Isle of Sheppey), so any similarity between the names is mere coincidence. Without any suitable island matching Ptolemy's Counus Island, 20th century historians White and Yearsley posit the documented island to have been lost or reduced to an insignificant sandbank by subsidence and the constant effects of the sea. The settlement and agricultural development of