9000 YEARS OF SEA-LEVEL CHANGE ALONG THE SOUTHERN AFRICAN COASTLINE

Beachrocks are good indicators of sea-level stillstands on microtidal coastlines and data for this sea-level curve is mainly based on dating a series of Holocene beachrocks and planation episodes on the southea st African coastline. Sea-level reached its present level along the so uthern African coastline at ca. 6500 BP; sea-level then rose depositin g a series of beachrocks at an elevation of + 2.75 m. This mid-Holocen e sea-level highstand persisted for a period of 2500 years with a + 3. 5 m stillstand, dated at 4480 BP, being the highest sea-level reached during the Holocene. In post-Holocene sea-level optimum times, a regre ssion occurred lowering sea-level to its present level at 3880 BP and down to -2 m at approximately 3000 BP. Subsequently; sea-level rose to + 1.5 m at 1610 BP and attained its present level at about 900 BP. Th e mid-Holocene sea-level highstand appears to have resulted from a com bination of isostatic emergence and the steric expansion of seawater r elating to warmer ocean temperatures associated with the Holocene hyps ithermal event on the eastern Agulhas Bank.