top of page
RichardMM_the_formation_of_earth_volumetric_lighting_hyper_real_cbd3c86f-c69c-4d67-94ed-6c

Stratigraphic Column

Geologists use a vertical section called a stratigraphic column to show, from the oldest to the youngest rock units, formal names and rank (i.e., group, formation) and rock types (lithologies). The statigraphic column of the Western Cape, although not to scale, present a vertical transect of the geology of the Overberg.

Screenshot 2023-10-16 141458.png

A bullet point summary of the stratigraphy and geology of the Overberg region based on the stratigraphic column, from the oldest (650-500 million year ago / Ma) to the youngest (Present Day), can be found below.

 650– 500 Ma (Neoproterozoic to Cambrian)   N     C  

  • Saldanian Orogeny 

  • Gondwana mega-continent creation

  • Formation of Malmesbury Group

  • Intrusion of the Cape Granites 

500 – 375 Ma (Cambria to Devonian)   C     O     S     D

  • Table Mountain, Bokkeveld, Witteberg Groups

  • Continental rifting (pull-apart), basin deposition, Table Mountain sandstones, shales, glacial tillite

  • Bokkeveld Group marine deposits

 

375 – 210 Ma: (Carboniferous to Triassic)  Ca    P     T

  • Carboniferous Dwyka glaciation

  • Karoo sedimentation and volcanism

  • Cape Fold Belt, compression, folding, thrusting, soft sediment deformation

 

180 – 65 Ma: (Jurassic to Cretaceous)   J     Cr

  • Gondwana Break-up; coastal margin formation

  • Continental uplift, erosion of coastal margins 

  • Uitenhage Group on the coastal margin 

  • Offshore carbonate-rich oil, gas bearing sediments

 

35 Ma – Present: (Cenozoic)   Ce

  • Silcretes of the Grahamstown Formation

  • Cenozoic coastal deposits

  • Fluctuating high (inter glacial) and low sea (glacial) levels causing erosion and deposition of Bredasdorp Group sediments

  • uplift of the continental margins

  • Peneplain development, cycles of sea-level rise and fall, formation of mega-aquifers

  • Human origins

References

​

Gresse, P.G. and Theron, J.N., 1992. The geology of the Worcester area. Explanation of Sheet 3319. Scale 1:250 000. Council for Geoscience.

Malan, J.A., Viloen, J.H.A., Siegfried, H.P. and Wickens, H. de V., 1994. Die geologie van die gebied Riversdale. Explanation of Sheet 3420. Scale 1:250 000. Council for Geoscience.

McCarthy, T. & Rubidge, B. 2005. The story of earth and life: 1–333. Cape Town: Struik.

Miller, D.E., 2020. Geological history of the Southwestern Cape. https://www.researchgate.net/publication/343739680

Norman, N. and Whitefield, B., 2006. Geological Journeys: A traveller’s guide to South Africa’s rocks and landforms.  Struik Publishers.

Rogers, J. 2018. Geological Adventures in the Fairest Cape: Unlocking the Secrets of its Scenery: 1–320. Pretoria: Council for Geoscience.

SACS (South African Committee for Stratigraphy).  1980.  Stratigraphy of South Africa.  Part 1: Lithostratigraphy of the Republic of South Africa, South West Africa/Namibia and the Republics of Bophuthatswana, Transkei and Venda (L.E. Kent, Compiler).  Handbook Geological Survey South Africa, 8: 1 – 690. 

bottom of page