Cenozoic

Izinhlamvana ezingahlangene - ileveli yolwandle engakaziki

Map Cenozoic

Ngesikhathi se-Cenozoic umaka wolwandle waqala wehla usuka ezindaweni eziphakeme owazwakala ngesikhathi se-Cretaceous. Uchungechunge lwamagquma amaningi alandelanayo abheke ndawonye akheka ezindaweni eziningi ezingasogwini lakwaKZN. EThekwini lokhu kwakhiwa amagquma ase-Bluff nase-Berea. Ezindaweni eziningi ukuguguleka okujulile kwamagqunyana amadala kukhiphe (kuzale) umhlabathi obomvu ngokujulile obizwa ngokuthi i-Berea Red Sand.

Berea red sand
i-Berea red sandi-Berea red sand
4x magnified
The Bluff, Durban
The Bluff, Durban (Photo: T. Reinhardt)

Ezikhathini eziningi zamanje, ukwehla nokwenyuka komaka wolwandle kuqhubekile nokulungisa ugu lakwaKZN. Amagqunyana amasha asogwini aqukethe amatshe anomnotho afana ne-ilmenite, i-rutile ne-zircon, ambiwa e-Richards Bay. 

Heavy mineral concentrate

The ilmenite and rutile are smelted to produce titanium metal and white pigments (mostly for paint). The zircon is used for glazing on tiles and pottery, and as a metal alloy.

Titanium and zirconium rich minerals are significantly denser than common sedimentary minerals. As a result they became locally concentrated through their movement by wind and water through gravitational separation. This explains the dark areas on the beach.

Heavy mineral concentration
Heavy mineral concentration of the Richards Bay mineral deposits .

(Source: Fockema P D,  1986 – The heavy mineral deposits north of Richards Bay)

KZN shoreline 18000 years ago 

Ngesikhathi sokugcina sokuhamba kweqhwa eminyakeni eyizigidi eziyishumi nesishiyangalombili umhlaba bewubanda nomaka wolwandle bewungaphansi kunamanje ngamamitha angaphezu kwekhulu. Ugu belungasolwandle kunamanje nemifula emikhulu yasika izigodi ezijulile ezigudla ugu. Ngenkathi umhlaba ufudumala nomaka wolwandle ukhuphuka, lezizigodi zagcwaliswa udaka lwamachweba nezihlabathi ezigcwele amagobongo ezilwane zasolwandle. Kungalesisizathu amabhuloho amaningi agudla usebe adinga izisekelo ezijulile ukuze zithinte amadwala angaphansi aqinile.

Late Quaternary Sea-Level Change in South Africa after P. Ramsay
Shallow marine sedimentary rock with bivalve fossils from the Uloa Pecten bed (11.6-5.3 million years). The specimen comes from an ancient beach deposit found near Uloa on the Mfolozi River. (Specimen: Geology Education Musuem)

Beach Sand (coastal sediments)

Coastal processes

Beach sands represent the weathered and eroded remnants of rocks found inland. KwaZulu-Natal beach sand is characteristically brownish in colour, consisting mainly of more resistant minerals such as quartz and feldspar. Of major economic importance, the sands also contain abundant quantities of the minerals ilmenite, rutile and zircon which are mined near Richards Bay for titanium and zirconium.