Earth:Ecca Group

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Short description: Second of the main subdivisions of the Karoo Supergroup of geological strata in southern Africa
Ecca Group
Stratigraphic range: Late Late Carboniferous-Early Permian
~303–290 Ma
TypeGeologic group
Sub-unitsWestern/Northwestern facies: Prince Albert Formation, Whitehill Formation, Collingham Formation, Tierberg Formation, Skoorsteenberg Formation, Kookfontein Formation, Waterford Formation.Southern facies: Prince Albert Formation, Whitehill Formation, Collingham Formation, Vischkuil Formation, Laingsburg Formation, Fort Brown Formation, Waterford Formation. Northeastern facies: Pietermaritzburg Formation, Vryheid Formation, Volksrust Formation
UnderliesBeaufort Group
OverliesDwyka Group
Lithology
PrimaryShale, mudstone, claystone, siltstone, chert, dolomite, coal
OtherQuartzite, pyrite
Location
RegionWestern & Eastern Cape
Country South Africa  Eswatini  Namibia  Botswana  Zimbabwe
Type section
Named forEcca
Geology of Karoo Supergroup.png
A simplified geological map of the outcrops of Karoo Supergroup rocks in Southern Africa. The Ecca Group is represented by the orange key on the map.

The Ecca Group is the second of the main subdivisions of the Karoo Supergroup of geological strata in southern Africa. It mainly follows conformably after the Dwyka Group in some sections, but in some localities overlying unconformably over much older basement rocks. It underlies the Beaufort Group in all known outcrops and exposures. Based on stratigraphic position, lithostratigraphic correlation, palynological analyses, and other means of geological dating, the Ecca Group ranges between Early to earliest Middle Permian (Asselian - Roadian) in age.[1][2][3]

Background

During the time of the deposition of the Ecca Group, the depositional environment, with some exceptions, was predominantly marine. The Ecca sea was vast but shallow, reaching only around 500 m at its deepest in its west/northwestern and southern facies where the Tanqua and Laingsburg Depocenters are situated respectively. The marine environment ranged from deep pelagic, submarine fan systems in the lower deposits which grade steadily north-eastwards to shallow marine deposits including shelf (continental) marine and marginal marine facies, and finally to beach deposits in younger successions. Coal-bearing fluvial-deltaic, and peatbog settings are also well known from the Ecca Group.[3][4][5][6]

The Ecca Group was deposited in a vast retroarc foreland basin. This foreland system was caused by crustal uplift (orogenesis) that had previously begun to take course due to the subduction of the Palaeo-pacific plate beneath the Gondwanan Plate. This resulted in the rise of the Gondwanide mountain range in what is known as the Gondwanide orogeny. The mountain-building and erosion caused by the growing Gondwanide mountain range was the initial subsidence mechanism acting on the Karoo Basin. Flexural tectonics partitioned the Karoo Basin into the foredeep, forebulge, and backbulge flexural provinces. This resulted in deposition of the Karoo Basin.[7][8][9][10][11]

Geographic extent

A mountain in the Tanqua Karoo, South Africa, with multiple layers of turbidites formed in the south-western portion of the Karoo Sea about 300 million years

The rocks of the Ecca Group first appear near Sutherland in its westernmost deposits, and continues east through Laingsburg, Prince Albert, Jansenville, Grahamstown, and up until the coast near Port Alfred. In the central north deposits are found near Britstown, running along the Orange River between Petrusville and Hopetown. In the extreme northeast deposits are found east of Johannesburg past Vryheid, Durban, Pietermaritzburg and all the way down to Port St. Johns in the southeast.[12][13]

Stratigraphic units

The Ecca Group comprises sixteen recognized geological formations.[14] These individual formations have been grouped into three geographical areas, which are the southern, western/northwestern, and northeastern facies successions. In the east of South Africa there are deposits of as of yet undifferentiated mudstone sequences attributed to the Ecca Group.[15][16][17][18][19]

With the exception of the Prince Albert, Whitehill, Collingham, and the uppermost Waterford Formations which are found in both the southern and western/northwestern facies, the geological formations of the Ecca Group can only be found in one of the three previously aforementioned facies successions. This is because each of these facies successions represents differing preserved environments that can be observed in their diagnostic geological features. The facies successions, along with their geological formations, are described below:[20][21][22][23][24]

Western/Northwestern Ecca facies

This facies succession is purely marine. The rocks contain a complete transition, grading laterally into one other, from basin-floor marine deposits through to channelized submarine slope to shelf, pro-delta and beach environment deposits. The deposits of the western/northwestern facies fall within the Tanqua Depocenter, one of the vast submarine fan systems known from the marine Ecca.[25] Associated formations are listed below (from oldest to youngest):

A fossil Mesosaurus tenuidens (syn.Mesosaurus brasiliensis), Permian (270 myo)
  • Collingham Formation: Is composed of thin beds of siliceous, dark grey mudstone alternated with softer, yellow-grey tuff beds. The fine-grained nature of the sediments indicate that the depositional environment was a low energy suspension setting in a submarine fan environment. The presence of tuff beds indicates that volcanic activity took place during the time of sediment deposition.
  • Tierberg Formation: Predominantly composed of blackish, planar, argillaceous shales. Tuff beds are found in the lower sections of this formation while calcareous concretions and clay pellet conglomerates are found in the upper sections. Upwards-coarsening sequences of mudstones, siltstones, and sandstones that exhibit ball-and-pillow structures are also found in the uppermost sections. The presence of the shales in the lower Tierberg indicate a low energy marine environment that transitioned to pro-delta to distal delta depositional environments with the appearance of the upward coarsening sequences and other associated geological features. Various invertebrate fossils have been recovered, namely fish scales, sponge spiracles, and trace fossils of Planolites and Nereites.
  • Skoorsteenberg Formation: Only found in the southernmost area of the western facies. A lens-shaped formation composed of five sandstone-rich units that are interbedded with shale layers. These contain bouma turbidite sequences. The depositional environment is thought to have been an unstable delta-front slope of a fluvial delta system. Trace fossils of worm feeding trails and Glossopteris fossils are common.
  • Kookfontein Formation: The lower section of this formation is composed of horizontally laminated dark-grey shales that are interbedded with clastic rhythmites. Minor upward thickening cycles are observed here which grow more prominent in the upper sections. The rock type changes in the upper sections to alternating siltstone and fine-grained sandstone beds. This formation is a continuation of the environmental facies of the Skoorsteenberg Formation where sediments were deposited in a pro-delta setting.
  • Waterford Formation: The western/northwestern deposits of this formation are composed of a mix of shale, siltstone, rhythmite, and fine to medium-grained sandstones. The sandstones and siltstones are horizontally laminated and often exhibit wave-rippled surfaces. Alternating slump and slide and coarsening upward cycles are observed in the lower sections while in the upper sections ball-and-pillow structures and channel-fill deposits are observed. These features indicate that the depositional environment constituted delta front deposits in the lower sections which transitioned to a fluvial delta-plain. Fossilized tree logs are frequently found in the sandstone layers, and in the other rock layers Cruziana and Skolithos burrow traces are found. Together with the underlying Tierberg, Skoorsteenberg, and Kookfontein Formation, the Waterford Formation forms an upward-coarsening deltaic megacycle.[31][32][33]

Southern Ecca facies

This facies succession is the largest of the three facies succession. Its lowermost formations are deep marine comprising basin floor pelagic sediments and submarine fan systems that grade upwards into channelized submarine slopes to shelf marine and beach environments. The Laingsburg Depocenter is found in this facies succession and include the following formations (from oldest to youngest):

  • Prince Albert Formation: Black to dark grey chert layers with yellowish grey weathering are only known from the southern facies. These rock sediments were deposited in a deep marine and distal submarine fan setting. Various invertebrate marine fossils, palaeoniscoid fishes, and coprolites have been recovered from this formation.
  • Whitehill Formation: In the southern facies the Whitehill Formation loses its diagnostic white band marker horizon. The rock type changes here to light brown, fine-grained sandstone and siltstone deposits that contain carbonate concretions. Tuff deposits also occur intermittently. It is regarded as a distal, southern equivalent of the Vryheid Formation.
  • Collingham Formation: The southern facies deposits of this formation yield diagnostic pale yellowish-grey chert, often referred to in literature as the “Maijiesfontein Chert Bed”.
  • Vischkuil Formation: Dominated by dark coloured shale in its westernmost outcrops which grade into greywacke sandstones in the east. The shale layers alternate with subordinate sandstones, siltstones, and minor yellow-grey tuff deposits. The shale layers often contain calcareous and phosphatic lenses, and also liesegang rings. The depositional environment is considered to have been deep marine within a basin-plain or outer basin-floor fan. The presence of tuff layers indicates that volcanic activity took place during the time of deposition.
  • Laingsburg Formation: Composed of four, massive sandstone units that are interbedded with planar-laminated shale and siltstones. Calcareous concretions and clay pebble clasts are often found in the massive sandstones. Coalified plant fragments are frequently found in the shale and siltstone layers. It grades laterally into the upper Ripon Formation in the east.
  • Ripon Formation: Consists mainly of tabular, poorly-sorted fine-grained sandstones. The sandstones alternate with dark-grey clastic rhythmite composed of thin, sandstone/siltstone layers. Spherical, calcareous concretions are found in the sandstone layers along with larger, brown-weathering calcareous structures. Various deformation structures, namely load casts and slump structures, are found here. Invertebrate fossil trackways and burrows occur throughout this formation. All these are indicative of a deep-water depositional environment. Carbonised plant fragments and fossil logs are also found.
  • Fort Brown Formation: Rhythmites of alternating sandstone/siltstone or siltstone/claystone layers, carbonaceous shales, and mudrocks, which are usually olive grey in color, are extremely common. The rhythmites and mudrock comprise the bulk of the lower deposits of the Fort Brown Formation. Minor impure sandstone wacke intercalations are found in its upper sections, displaying horizontal, wavy, ripple, and ripple-drift cross lamination. Tuffs are sometimes found due to the Cape Orogenic event taking place during the time of deposition. The mudrocks and shales are extremely fine-grained, finely laminated and are considered to represent shelf marine facies that were deposited in a pro-delta setting. Fragmentary plant hash material and invertebrate trace fossils are found here.
  • Waterford Formation:This formation is exposed along a series of east-west trending synclines and anticlines. It is rich in sandstones, which are generally light in colour and are frequently interbedded with dark-grey to light yellowish grey siltstone and sometimes mudstone. Well-preserved symmetrical wave ripples are often found in the sandstone layers. Outcrops of this formation are extremely diagnostic as a result of the alternating “bands” of sandstone and siltstone This is thought to represent a marginal marine setting either within the intertidal zone or within a delta or beach setting.[18][34][35][36]

Northeastern Ecca facies

The northeastern facies is shallow marine in its lowermost and uppermost sections, and then changes to coal-bearing fluvial-deltaic peat swamp settings in its central deposits. The northern facies often overlies unconformably on much older basement rocks unlike the other facies of the Ecca Group. It comprises three geological formations (from oldest to youngest):

Example of a peat swamp environment, similar to the depositional environment preserved in the Vryheid Formation rocks. Plant material would have sunk below surface to the bottom of the swamp, being preserved in the anoxic environment. Over time plant material would be compacted and buried by sediment. Over millions of years the plant material mineralized, becoming coal

Correlation

Biostratigraphic correlation of fossils in the greater Gondwana across present-day South America, southern Africa, Antarctica and Australia

The lower geological formations of the Ecca Group, particularly the rocks of the Whitehill Formation, correlate in age with the Huab Basin of northwestern Namibia, and lower formations of the Kalahari Basin found in Namibia, Botswana, and Zimbabwe. Near the small town of Khorixas in Namibia there is a locally well-known national monument called the Petrified Forest. Petrified logs were brought into the area and are considered to have been sourced from the nearby deposits of the Huab Basin.[44][45][46]

Fossil tree from the Permian Ecca Group of the Karoo Sequence at the petrified forest, east of Doro !Nawas, Namibia

Abroad, Ecca-aged deposits are known from the Paraná Basin of Brazil and the Petolas Basin of both Brazil and Uruguay where fossils of Mesosaurus and Glossopteris have also been recovered. Finally, geological dating has also proven the lower Ecca formations to correlate with the Barnett Shale and Marcellus Formation of the United States .

See also

References

  1. ↑ Visser, J. C.; Loock, J. N. J. & (1978-05-01). "Water depth in the Main Karoo Basin, South Africa, during Ecca (Permian) sedimentation" (in en). South African Journal of Geology 81 (2): 185–191. ISSN 1996-8590. https://journals.co.za/content/sajg/81/2/AJA10120750_2896. 
  2. ↑ R.M.H. Smith, P.G.Eriksson, W.J.Botha (1993-01-01). "A review of the stratigraphy and sedimentary environments of the Karoo-aged basins of Southern Africa" (in en). Journal of African Earth Sciences (and the Middle East) 16 (1–2): 143–169. doi:10.1016/0899-5362(93)90164-L. ISSN 0899-5362. Bibcode: 1993JAfES..16..143S. 
  3. ↑ 3.0 3.1 Jirah, Sifelani; McPhee, Blair W.; Viglietti, Pia A.; Bamford, Marion K.; Choiniere, Jonah N.; Hancox, P. John; Barbolini, Natasha; Day, Michael O. et al. (2016), "Advances in Nonmarine Karoo Biostratigraphy: Significance for Understanding Basin Development" (in en), Origin and Evolution of the Cape Mountains and Karoo Basin, Regional Geology Reviews (Springer, Cham): pp. 141–149, doi:10.1007/978-3-319-40859-0_14, ISBN 9783319408583 
  4. ↑ 4.0 4.1 Hobday, David K. (1977) (in en-US). Fluvial Deposits of the Ecca and Beaufort Groups in the Eastern Karoo Basin, Southern Africa. pp. 413–429. http://archives.datapages.com/data/cspg_sp/data/005/005001/413_cspgsp0050413.htm. 
  5. ↑ Richard G.Vos, David K.Hobday (1977-01-01). "Storm beach deposits in the late Palaeozoic Ecca Group of South Africa" (in en). Sedimentary Geology 19: 217–232. doi:10.1016/0037-0738(77)90032-X. ISSN 0037-0738. Bibcode: 1977SedG...19..217V. 
  6. ↑ Van Vuuren, C.J. and Cole, D.I., 1979. The stratigraphy and depositional environments of the Ecca Group in the northern part of the Karoo Basin. Geological Society of South Africa Special Publication, 6, pp.103-111.
  7. ↑ Rubidge, B. S.; Hancox, P. J.; Catuneanu, O. (1998-12-01). "Reciprocal flexural behaviour and contrasting stratigraphies: a new basin development model for the Karoo retroarc foreland system, South Africa" (in en). Basin Research 10 (4): 417–439. doi:10.1046/j.1365-2117.1998.00078.x. ISSN 1365-2117. Bibcode: 1998BasR...10..417C. http://www.earthdoc.org/publication/publicationdetails/?publication=62697. 
  8. ↑ O. Catuneanu, P.J Hancox, B. Cairncross, and B.S Rubidge (2002-11-01). "Foredeep submarine fans and forebulge deltas: orogenic off-loading in the underfilled Karoo Basin" (in en). Journal of African Earth Sciences 35 (4): 489–502. doi:10.1016/S0899-5362(02)00154-9. ISSN 1464-343X. Bibcode: 2002JAfES..35..489C. 
  9. ↑ O. Catuneanu, H. Wopfner, P.G. Eriksson, B. Cairncross, and B.S.Rubidge, R.M.H. Smith, and P.J. Hancox (2005-10-01). "The Karoo basins of south-central Africa" (in en). Journal of African Earth Sciences 43 (1–3): 211–253. doi:10.1016/j.jafrearsci.2005.07.007. ISSN 1464-343X. Bibcode: 2005JAfES..43..211C. 
  10. ↑ Cj, Van Vuuren (2016-09-22) (in en). A basin analysis of the northern facies of the Ecca group. http://nrfnexus.nrf.ac.za/handle/20.500.11892/95346. 
  11. ↑ Waschbusch, Paula; Beaumont, Christopher; Catuneanu, Octavian (1997-12-01). "Interplay of static loads and subduction dynamics in foreland basins: Reciprocal stratigraphies and the "missing" peripheral bulge" (in en). Geology 25 (12): 1087–1090. doi:10.1130/0091-7613(1997)025<1087:IOSLAS>2.3.CO;2. Bibcode: 1997Geo....25.1087C. https://pubs.geoscienceworld.org/gsa/geology/article-abstract/25/12/1087/187381/interplay-of-static-loads-and-subduction-dynamics. 
  12. ↑ Baiyegunhi, Christopher; Liu, Kuiwu; Gwavava, Oswald (2017). "Grain size statistics and depositional pattern of the Ecca Group sandstones, Karoo Supergroup in the Eastern Cape Province, South Africa". Open Geosciences 9 (1): 554–576. doi:10.1515/geo-2017-0042. Bibcode: 2017OGeo....9...42B. 
  13. ↑ 13.0 13.1 B. Cairncross (1989-06-01). "Paleodepositional environments and tectonosedimentary controls of the postglacial Permian coals, Karoo Basin, South Africa" (in en). International Journal of Coal Geology 12 (1–4): 365–380. doi:10.1016/0166-5162(89)90058-X. ISSN 0166-5162. 
  14. ↑ Visser, J. N. J. (1992-01-01). "Deposition of the Early to Late Permian Whitehill Formation during a sea-level highstand in a juvenile foreland basin" (in en). South African Journal of Geology 95 (5–6): 181–193. ISSN 1996-8590. https://journals.co.za/content/sajg/95/5-6/AJA10120750_607. 
  15. ↑ M.R Johnson, C.J Van Vuuren, W.F Hegenberger, R. Key, and U. Show (1996-07-01). "Stratigraphy of the Karoo Supergroup in southern Africa: an overview" (in en). Journal of African Earth Sciences 23 (1): 3–15. doi:10.1016/S0899-5362(96)00048-6. ISSN 1464-343X. Bibcode: 1996JAfES..23....3J. 
  16. ↑ Johnson, M.R., Van Vuuren, C.J., Visser, J.N.J., Cole, D.I., Wickens, H.D.V., Christie, A.D.M., Roberts, D.L. and Brandl, G., 2006. Sedimentary rocks of the Karoo Supergroup. The geology of South Africa, pp.461-499.
  17. ↑ Mve Nguema and Oliver Patrice (2005-12-01). Petrology, geochronology and provenance of the Laingsburg and Tanqua Karoo submarine fan systems, Ecca Group, South Africa (Thesis thesis). Stellenbosch: University of Stellenbosch.
  18. ↑ 18.0 18.1 Rubidge, Bruce S. (1990). "A new vertebrate biozone at the base of the Beaufort Group, Karoo sequence (South Africa)" (in en). Palaeontologia Africana. ISSN 0078-8554. http://wiredspace.wits.ac.za/handle/10539/16155. 
  19. ↑ Viljoen, J. H. A. (1994-01-01). "Sedimentology of the Collingham Formation, Karoo Supergroup" (in en). South African Journal of Geology 97 (2): 167–183. ISSN 1996-8590. https://journals.co.za/content/sajg/97/2/AJA10120750_659. 
  20. ↑ Veevers, J. J.; Powell, Chris McA (1994-01-01) (in en). Permian-Triassic Pangean Basins and Foldbelts Along the Panthalassan Margin of Gondwanaland. Geological Society of America. ISBN 9780813711843. https://books.google.com/books?id=WsOP_U8wJwoC&q=Cole,+D.I.,+1994.+Southern+Africa:+Karoo+basin+and+Cape+fold+belt.+Permian-Triassic+Pangean+Basins+and+foldbelts+along+the+Panthalassan+margin+of+Gondwanaland,+184,+p.223.&pg=PA223. 
  21. ↑ Kavanagh, John P.; Flint, Stephen S.; Hodgson, David M.; Figueiredo, Jorge J. P. (2010-01-01). "Depositional Environments and Sequence Stratigraphy of an Exhumed Permian Mudstone-Dominated Submarine Slope Succession, Karoo Basin, South Africa" (in en). Journal of Sedimentary Research 80 (1): 97–118. doi:10.2110/jsr.2010.002. ISSN 1527-1404. Bibcode: 2010JSedR..80...97F. https://pubs.geoscienceworld.org/sepm/jsedres/article-abstract/80/1/97/145293/depositional-environments-and-sequence. 
  22. ↑ Jorge J.P. Figueiredo, David M.Hodgson, Stephen S.Flint, and John P.Kavanagh (2013-03-01). "Architecture of a channel complex formed and filled during long-term degradation and entrenchment on the upper submarine slope, Unit F, Fort Brown Fm., SW Karoo Basin, South Africa" (in en). Marine and Petroleum Geology 41: 104–116. doi:10.1016/j.marpetgeo.2012.02.006. ISSN 0264-8172. 
  23. ↑ Kingsley, C. S. (1981-01-01). "A composite submarine fan-delta-fluvial model for the Ecca and Lower Beaufort Groups of Permian Age in the Eastern Cape Province, South Africa" (in en). South African Journal of Geology 84 (1): 27–40. ISSN 1996-8590. https://journals.co.za/content/sajg/84/1/AJA10120750_2792. 
  24. ↑ Baiyegunhi, Christopher; Nxantsiya, Zusakhe; Pharoe, Kinshasa; Baiyegunhi, Temitope L.; Mepaiyeda, Seyi (1 January 2019). "Petrographical and geophysical investigation of the Ecca Group between Fort Beaufort and Grahamstown, in the Eastern Cape Province, South Africa" (in en). Open Geosciences 11 (1): 313–326. doi:10.1515/geo-2019-0025. ISSN 2391-5447. Bibcode: 2019OGeo...11...25B. 
  25. ↑ Wickens, H.D.V., 1992. Submarine fans of the Permian Ecca Group in the SW Karoo Basin: Their origin and reflection on the tectonic evolution of the basin and its source areas. Inversion Tectonics of the Cape Fold Belt, Karoo and Cretaceous Basins of Southern Africa, pp.117-125.
  26. ↑ Tietjen, Kristen; Criswell, Katharine E.; Finarelli, John A.; Gess, Robert W.; Coates, Michael I. (2017-01-01). "A symmoriiform chondrichthyan braincase and the origin of chimaeroid fishes" (in en). Nature 541 (7636): 208–211. doi:10.1038/nature20806. ISSN 1476-4687. PMID 28052054. Bibcode: 2017Natur.541..208C. 
  27. ↑ D.c, Araujo; B.w, Oelofsen (1987) (in en). Mesosaurus tenuidens and Stereosternum tumidum from the Permian Gondwana of both Southern Africa and South America.. https://scholar.sun.ac.za:443/handle/10019.1/9746. 
  28. ↑ R.M.H. Smith (1990-01-01). "A review of stratigraphy and sedimentary environments of the Karoo Basin of South Africa" (in en). Journal of African Earth Sciences (and the Middle East) 10 (1–2): 117–137. doi:10.1016/0899-5362(90)90050-O. ISSN 0899-5362. Bibcode: 1990JAfES..10..117S. 
  29. ↑ Modesto, Sean Patrick (2006-03-01). "The cranial skeleton of the Early Permian aquatic reptile Mesosaurus tenuidens: implications for relationships and palaeobiology" (in en). Zoological Journal of the Linnean Society 146 (3): 345–368. doi:10.1111/j.1096-3642.2006.00205.x. ISSN 0024-4082. 
  30. ↑ Modesto, S. P. (2010-09-15). "The postcranial skeleton of the aquatic parareptile Mesosaurus tenuidens from the Gondwanan Permian". Journal of Vertebrate Paleontology 30 (5): 1378–1395. doi:10.1080/02724634.2010.501443. 
  31. ↑ Claire Geel, Hans-Martin Schulz, Peter Booth, Maarten de Wit, Brian Horsfield (2013-01-01). "Shale Gas Characteristics of Permian Black Shales in South Africa: Results from Recent Drilling in the Ecca Group (Eastern Cape)" (in en). Energy Procedia 40: 256–265. doi:10.1016/j.egypro.2013.08.030. ISSN 1876-6102. 
  32. ↑ Richard G. Vos and David K. Hobday (1977-01-01). "Storm beach deposits in the late Palaeozoic Ecca Group of South Africa" (in en). Sedimentary Geology 19: 217–232. doi:10.1016/0037-0738(77)90032-X. ISSN 0037-0738. Bibcode: 1977SedG...19..217V. 
  33. ↑ Evans, F. J. (Fiona Jocelyn) (2005-12-01). Taxonomy, palaeoecology and palaeobiogeography of some palaeozoic fish of Southern Gondwana (Thesis thesis). Stellenbosch: Stellenbosch University.
  34. ↑ Almond, J.E., 2005. PALAEONTOLOGICAL IMPACT ASSESSMENT: Exceptional fossil starfish bed, Prince Albert District, Western Cape. John E. Almond (Natura Viva cc, Cape Town) and Derek Ohland (Iziko Museums, Cape Town). January 2005.
  35. ↑ Almond, J.E., 2010. PALAEONTOLOGICAL IMPACT ASSESSMENT: DESKTOP & FIELD SCOPING STUDY Waste Water Treatment Works, Water Pipeline and Low Income Housing Development, Klaarstroom, Prince Albert Municipality, Western Cape Province. John E. Almond (Natura Viva cc, Cape Town). April 2010.
  36. ↑ Almond, J.E., 2013. PALAEONTOLOGICAL SPECIALIST STUDY: FIELD ASSESSMENT. Expansion of an existing Borrow Pit in the Prince Albert townlands, Prince Albert District, Western Cape. John E. Almond (Natura Viva cc, Cape Town). March 2013.
  37. ↑ Collinson, J. D.; Lewin, John (2009-04-15) (in en). Modern and Ancient Fluvial Systems. John Wiley & Sons. ISBN 9781444303780. https://books.google.com/books?id=AHzLg37QsLQC&q=+Turner,+B.R.+and+Whateley,+M.K.,+1983.+Structural+and+sedimentological+controls+of+coal+deposition+in+the+Nongoma+graben,+northern+Zululand,+South+Africa.+In+Modern+and+ancient+fluvial+systems+(Vol.+6,+pp.+457-471).+Blackwell+Scientific+Publications+Oxfor&pg=PA457. 
  38. ↑ B.R. Turner, G. Stanistreet, M.K.G. Whateley (1981-11-01). "Trace fossils and palaeoenvironments in the Ecca group of the Nongoma Graben, northern Zululand, South Africa" (in en). Palaeogeography, Palaeoclimatology, Palaeoecology 36 (1–2): 113–123. doi:10.1016/0031-0182(81)90053-5. ISSN 0031-0182. Bibcode: 1981PPP....36..113T. 
  39. ↑ Prevec, R., 2014. PHASE 1 PALAEONTOLOGICAL IMPACT ASSESSMENT. Link: https://www.sahra.org.za/sahris/sites/default/files/heritagereports/PIA_Mbila%20Phase%20I_Prevec%20March%202014_revised%20Final.pdf
  40. ↑ Cole, D.I. and McLachlan, I.R., 1991. Oil potential of the Permian Whitehill Shale Formation in the Main Karoo Basin, South Africa. Proceedings, Gondwana Seven: São Paulo, Instituto de Geociencias, Universidade de São Paulo, pp.379-390.
  41. ↑ Anderson, J. M. (1973). "THE BIOSTRATIGRAPHY OF THE PERMIAN AND TRIASSIC" (in en). Palaeontologia Africana. ISSN 0078-8554. http://wiredspace.wits.ac.za/handle/10539/16041. 
  42. ↑ Anderson, J.M. and Cruickshank, A.R.J., 1973. The biostratigraphy of the Permian and Triassic, Part 2. A preliminary review of the distribution of Permian and Triassic strata in time and space. Palaeontol. Aft, 16, pp.59-83.
  43. ↑ Stanistreet, I.G., Le Blanc Smith, G. and Cadle, A.B.. "Trace fossils as sedimentological and palaeoenvironmental indices in the Ecca Group (Lower Permian) of the Transvaal. Transactions of the Geological Society of South Africa, 83, pp.333-344.". https://www.researchgate.net/publication/281547148. 
  44. ↑ Pickford, Martin (1995). "Karoo supergroup palaeontology of Namibia and brief description of a Thecodont from Omingonde" (in en). Palaeontologia Africana. ISSN 0078-8554. http://wiredspace.wits.ac.za/handle/10539/16388. 
  45. ↑ Vogt, A., 2004. National monuments in Namibia: An inventory of proclaimed national monuments in the Republic of Namibia. Gamsberg Macmillan.
  46. ↑ Marion K. Bamford (2004-01-01). "Diversity of the Woody Vegetation of Gondwanan Southern Africa" (in en). Gondwana Research 7 (1): 153–164. doi:10.1016/S1342-937X(05)70314-2. ISSN 1342-937X. Bibcode: 2004GondR...7..153B. 



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