Geodetic aspects concerning possible subsidence in southeastern England

Abstract

The various geodetic levellings carried out by the Ordnance Survey are reviewed briefly and the evidence of land movement in Great Britain shown by the results of these levellings is considered. Current lower order levelling in southeast England is compared with levelling carried out before 1949 described by Longfield (1932) and Lloyd (1831). Attention is drawn to the existence of deep bench marks in London. Consideration is given o e a that is needed to ensure that the relative movements of land and sea can be suitably monitored in the future.