Anomalies in the vertical datums of Barbardos, West Indies

It has been long acknowledged by surveyors working on the island of Barbados that the land survey datum of the island is some 0.3 m above Mean Sea Level (MSL). To differentiate the two levels the land survey datum is termed the Lamont datum after the organisation that founded the original mark on which it is based. The Admiralty operated independently in establishing a relationship between MSL and Chart Datum for navigational purposes, and fifty year later found the need to increase this difference by 0.24 m. A relative increase in sea level at the adjacent land mass is an obvious explanation for the datum difference, but clearly does not constitute the whole of the discrepancy. In considering intermittent sea level observations made over the last 50 years it is now proposed that the reference for the primary vertical control mark for the country has been misinterpreted. At the time of establishment of land survey datum the offset was closer to 0.4 m. It is suggested that sea level is falling relative to the land mass, and that the difference between land survey datum and mean sea level has reduced to 0.36 m in the present day.