SciELO - Scientific Electronic Library Online

vol.108 issue7-8Modern beachrock formation in Durban, KwaZulu-Natal author indexsubject indexarticles search
Home Pagealphabetic serial listing  

South African Journal of Science

On-line version ISSN 1996-7489
Print version ISSN 0038-2353


GREEN, Andrew; LEUCI, Rio; THACKERAY, Zane  and  VELLA, Godfrey. Number One Reef: an overstepped segmented lagoon complex on the KwaZulu-Natal continental shelf. S. Afr. j. sci. [online]. 2012, vol.108, n.7-8, pp.113-118. ISSN 1996-7489.

This study of the bathymetry of the mid-shelf of the Durban Bight, KwaZulu-Natal revealed a series of previously undocumented seafloor features. These features were mapped using a high-resolution multibeam bathymetric echosounder and a detailed map of the seafloor topography was produced. We recognised several features that closely resemble features of contemporary segmented lagoon and lake systems: semicircular seafloor depressions, arcuate ridges, cuspate spits and prograding submerged barriers. Based on the striking similarity in morphology to Kosi Bay - a segmented lagoon system from the sandy northern KwaZuluNatal coastal plain - a similar evolutionary model is proposed. This model is of an incised valley formed following a sea level lowering to the Last Glacial Maximum at about 18 000 BP. Thereafter, continued transgressive infilling occurred to a point where an extensive lagoon and back-barrier system was established. At this point, sea levels remained static, causing the net segmentation of the system and the slow closure of the tidal basins or circular depressions. This type of seafloor topography is rarely preserved and is the result of fortuitous cementation after deposition and the later removal of sediment that would ordinarily bury such features.

        · text in English     · English ( pdf )


Creative Commons License All the contents of this journal, except where otherwise noted, is licensed under a Creative Commons Attribution License