Aspects of the geology and geomorphology of Lake Bangazi North: a palaeo-estuary to the Mkhuze River.

Abstract

This research examines the geological evolution of Lake Bangazi North, on the east coast of northern KwaZulu-Natal, South Africa. Very little research has been conducted on this area and as a result the information provided in this paper will serve as the one of the first research pieces on the area. The geophysical and seismic stratigraphy, changing palaeo-environments relating to the change in contemporary geomorphology using bathymetry and satellite imagery are described for the area of Lake Bangazi. These data were collected and interpreted via geophysical and seismic reflection data, multibeam bathymetry and remote sensing. Geochemical analyses on a core sample taken from the lake provided a quantitative interpretation of the lake sediment, linking the recent development to the broader geological history. The change in sea level following the Late Pleistocene and Holocene era had a significant effect on coastal systems. Lake Bangazi like other coastal systems along the east coast of KwaZulu-Natal such as St Lucia estuary, Kosi Bay and Lake Sibaya shows similar changes with the interaction of the Pleistocene dune barrier complex influencing the development of these systems. It is theorised that Lake Bangazi was once connected to the St Lucia estuary. Lake Bangazi has been isolated from the St Lucia estuary for a significant period of time where it has only been affected by prolonged periods of drought, thereby ensuring a high preservation potential allowing for an accurate geological evolution to be drawn from the stratigraphic record. An unexpected, yet interesting, aspect of this study shows the relationship that wildlife, specifically hippos, can have with waterbodies and the impact their role as bio-engineers play in the development of these waterbodies.