Jump to content

Algoa Group

From Wikipedia, the free encyclopedia
Algoa Group
Stratigraphic range: Middle Eocene-Holocene
~41–0 Ma
TypeGeologic group
Sub-unitsBathurst Formation, Alexandria Formation, Nanaga Formation, Salnova Formation, Nahoon Formation, Schelm Hoek Formation
OverliesTable Mountain Group or Uitenhage Group
Lithology
PrimarySandstone, calcareous sandstone, limestone, coquina & conglomerates
OtherCalcite
Location
Country South Africa
Type section
Named forAlgoa area

The Algoa Group is one of five geological groups which comprise the coastal Cenozoic geological deposits in South Africa. The Algoa Group contains six formations which range from Middle Eocene to Late Holocene in age (~41Ma - 100Ka).[1][2][3]

Geographic extent

[edit]

The geological successions of the Algoa Group outcrop from Plettenberg Bay in the Western Cape to East London in the Eastern Cape of South Africa. There are also putative outcrops of Algoa Group rocks further NE in the Port St Johns area. The Algoa Group rocks overlie unconformably and parauncomformably in some areas over much older rocks of the Table Mountain Group in the west and over the Uitenhage Group in the east.[4][5][6]

Stratigraphic units

[edit]

Stratigraphic units in this group include (from oldest to youngest):

Paleontology and archaeology

[edit]

Fossils are more frequently found in the older formations, although the Alexandria and Salnova formations are the most fossil rich. The most common fossils are of invertebrates, namely of marine gastropods and bivalves, and trace fossils left such as of burrows left by invertebrates. Vertebrate trackways of birds and modern humans are known from the Nahoon Formation.[18]

The Nahoon and Schelm Hoek Formations are known for their archeological artefacts, including modern human trackways in the case of the Nahoon Formation. Both these formations have yielded stone tools. Shell middens and evidence of for small, coastal human settlements are known from the Schelm Hoek Formation.[19][20][21]

References

[edit]
  1. ^ Roberts, D. L., Botha, G. A., Maud, R. R., Pether, J., and Johnson, M. R. (2006). Coastal cenozoic deposits. The geology of South Africa. Johannesburg/Pretoria: Geological Society of South Africa/Council for Geoscience, 605-628.
  2. ^ Dingle, R.V., Siesser, W.G. and Newton, A.R., 1983. Mesozoic and Tertiary geology of southern Africa. Rotterdam: Balkema.
  3. ^ Partridge, R.R., 1987. Geomorphic evolution of southern Africa since the Mesozoic. South African Journal of Geology, 90(2), pp.179-208.
  4. ^ Roberts, D.L., Botha, G.A., Maud, R.R., Pether, J. and Johnson, M.R., 2006. Coastal cenozoic deposits. The geology of South Africa. Johannesburg/Pretoria: Geological Society of South Africa/Council for Geoscience, pp.605-628.
  5. ^ Roux, F. G. Le (1990-07-01). "Palaeontological correlation of Cenozoic marine deposits of the southeastern, southern and western coasts, Cape Province". South African Journal of Geology. 93 (3). ISSN 1012-0750.
  6. ^ G., Le Roux, F. (August 1989). The lithostratigraphy of Cenozoic deposits along the south-east Cape coast as related to sea-level changes (Thesis). Stellenbosch : Stellenbosch University.{{cite thesis}}: CS1 maint: multiple names: authors list (link)
  7. ^ Siesser, W. G. Maud, R. R., Partridge, T. C. & (1987-09-01). "An Early Tertiary marine deposit at Pato's Kop, Ciskei". South African Journal of Geology. 90 (3). ISSN 1012-0750.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  8. ^ Almond, J.E., 2012. Proposed prospecting for and mining of fossiliferous marine limestone of Eocene age near Bathurst, Bathurst District, Eastern Cape. Link: http://www.sahra.org.za/sahris/sites/default/files/heritagereports/PIA-Laman%20Lime%20Prospecting,%20Bathurst,%20EC%202012%20%5B1%5D.pdf
  9. ^ King, L. (1972-05-01). "Pliocene marine fossils from the Alexandria Formation in the Paterson District, Eastern Cape Province, and their geomorphic significance". South African Journal of Geology. 75 (2). ISSN 1012-0750.
  10. ^ McMillan, I. K. (1990-08-01). "A foraminiferal biostratigraphy and chronostratigraphy for the Pliocene to Pleistocene Upper Algoa Group, eastern Cape, South Africa". South African Journal of Geology. 93 (4). ISSN 1012-0750.
  11. ^ Le Roux, F.G., 1988. The Alexandria, Nanaga and Salnova Formations redefined and their stratigraphic positions in the Algoa Group. Geoconl {ress' 88. Ext. Abstr. 22nd Earth Science Conl {ress, Geo/. Soc. S. Afr, pp.363-366.
  12. ^ Le Roux, F.G., 1989. Lithostratigraphy of the Nahoon Formation (Algoa Group) (No. 9). Republic of South Africa, Department of Mineral and Energy Affairs, Geological Survey.
  13. ^ Partridge, T.C., Avery, D.M., Botha, G.A., Brink, J.S., Deacon, J., Herbert, R.S., Maud, R.R., Scholtz, A., Scott, L., Talma, A.S. and Vogel, J.C., 1990. Late pleistocene and holocene climatic-change in Southern Africa. South African Journal of Science, 86(7-10), pp.302-306.
  14. ^ Roberts, David L. (2008-12-03). "Last Interglacial Hominid and Associated Vertebrate Fossil Trackways in Coastal Eolianites, South Africa". Ichnos. 15 (3–4): 190–207. Bibcode:2008Ichno..15..190R. doi:10.1080/10420940802470482. ISSN 1042-0940.
  15. ^ Roberts, D. L., Botha, G. A., Maud, R. R., Pether, J., and Johnson, M. R. (2006). Coastal cenozoic deposits. The geology of South Africa. Johannesburg/Pretoria: Geological Society of South Africa/Council for Geoscience, 605-628.
  16. ^ J. E. Almond (March, 2010) Coega IDZ Fossil Heritage PIA Part2 Natura Viva cc 41 3.3. ALGOA GROUP. Link: http://www.sahra.org.za/sahris/sites/default/files/heritagereports/Coega%20IDZ%20Fossil%20Heritage%20PIA%20Part2.pdf
  17. ^ Illenberger, W.K., 1992. Lithostratigraphy of the Schelm Hoek formation(Algoa group). Lithostratigraphic series.
  18. ^ Roberts, David L. (2008-12-03). "Last Interglacial Hominid and Associated Vertebrate Fossil Trackways in Coastal Eolianites, South Africa". Ichnos. 15 (3–4): 190–207. Bibcode:2008Ichno..15..190R. doi:10.1080/10420940802470482. ISSN 1042-0940.
  19. ^ Roberts, D. L., Botha, G. A., Maud, R. R., Pether, J., and Johnson, M. R. (2006). Coastal cenozoic deposits. The geology of South Africa. Johannesburg/Pretoria: Geological Society of South Africa/Council for Geoscience, 605-628.
  20. ^ J. E. Almond (March, 2010) Coega IDZ Fossil Heritage PIA Part2 Natura Viva cc 41 3.3. ALGOA GROUP. Link: http://www.sahra.org.za/sahris/sites/default/files/heritagereports/Coega%20IDZ%20Fossil%20Heritage%20PIA%20Part2.pdf
  21. ^ Partridge, T.C., Avery, D.M., Botha, G.A., Brink, J.S., Deacon, J., Herbert, R.S., Maud, R.R., Scholtz, A., Scott, L., Talma, A.S. and Vogel, J.C., 1990. Late pleistocene and holocene climatic-change in Southern Africa. South African Journal of Science, 86(7-10), pp.302-306.