Balfour Formation
Stratigraphic range:Lopingian -Induan 256.3–251.2 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Outcrops of the Balfour Formation are found in the hillsides surrounding Nieu-Bethesda, Eastern Cape, South Africa
Type	Geological formation
Unit of	Adelaide Subgroup,Beaufort Group
Sub-units	Oudeberg Member, Daggaboersnek Member, Ripplemead Member, Elandsberg Member, Palingkloof Member
Underlies	Katberg Formation
Overlies	Middleton Formation
Thickness	up to 2,150 m (7,050 ft)
Lithology
Primary	Mudstone,siltstone
Other	Sandstone
Location
Coordinates	32°18′S24°30′E / 32.3°S 24.5°E /-32.3; 24.5
Approximate paleocoordinates	62°42′S29°18′W / 62.7°S 29.3°W /-62.7; -29.3
Region	Northern Cape,Eastern Cape andFree State
Country	South Africa

TheBalfour Formation is ageological formation that is found in theBeaufort Group, a majorgeological group that forms part of the greaterKaroo Supergroup inSouth Africa. The Balfour Formation is the uppermost formation of the Adelaide Subgroup which contains all the LatePermian - EarlyTriassic aged biozones of theBeaufort Group.Outcrops and exposures of the Balfour Formation are found from east of 24 degrees in the highest mountainousescarpments betweenBeaufort West andFraserburg, but most notably in the Winterberg and Sneeuberg mountain ranges nearCradock, theBaviaanskloof river valley,Graaff-Reniet andNieu Bethesda in theEastern Cape, and in the southernFree State province.^[1][2]

The Balfour Formation overlies the Middleton Formation of the Adelaide Subgroup and underlies the Katberg Formation of the lower Tarkastad Subgroup, all comprising the greaterBeaufort Group. The Balfour Formation is composed of five members which are listed below (from oldest to youngest):

• Oudeberg Member
• Daggaboersnek Member
• Ripplemead Member
• Elandsberg Member
• Palingkloof member

The rocks of the Balfour Formation also incorporate the entireDaptocephalus Assemblage Zone, the lowermost portion of theLystrosaurus Assemblage Zone,^[3] and the uppermost rocks of theCistecephalus Assemblage Zone.^[4] Up until the middle section of the Ripplemead Member, the Balfour Formation correlates with the near contemporaneous Teekloof Formation west of the 24 degrees fromBeaufort West westwards, and to the Normadien Formation north of theOrange River. However, the Elandsberg and Palingkloof Members do not have any lateral correlates west of 24 degrees. This is either due to pasterosion of the upper, unknown members of the Teekloof Formation or there was a sudden cessation of sedimentary deposition in the western section of theKaroo Basin.^[5][6][7][8]

Thesedimentary rocks of this formation are composed predominantly of alternating greenish-grey, bluish-grey, and grey-ish redmudstone that often containsiltstonelenses. Themudstones are very fine-grained, massive and exhibit blocky weathering.Claystone successions are also found which, along with themudstones, frequently contain desiccation cracks, raindrop impressions, andcalcareousnodules orconcretions are found throughout.Rhythmites are also found.Sandstones are less common, but some notable units have been studied in the Balfour Formation. In the lowermost section of the Balfour is asandstone-rich unit known as the Oudeberg Member. Thesandstones in this unit are very fine-grained and are rich infeldspar. Another sandstone unit in the middle of the Balfour Formation is the Daggaboersnek Member which contains thin, tabular sandstones, and ripple structures are common.^[9][10]

The presence of these rocks reveal much about the past environment that they were deposited in. The dominance of fine-grainedmudstone and less common, fine-grainedsandstones indicates that the rock sediments were deposited in a low-energy,fluvial environment, most likely one that hadmeandering rivers. At the time of sedimentary deposition, the Karooretroarcforeland system was in an overfilled phase, and purely terrestrial sediments occupied theKaroo Basin at this time. As this formation includes the rocks of both theCistecephalus,Daptocephalus,Lystrosaurus Assemblage Zones, the Balfour Formation preserves the geological record for theend Permian extinction event. This is important as the end Permian extinction event was the largest massextinction event in the Earth's history. This was followed by one of the worst biotic crises, which is reflected in the sudden and drasticsedimentaryfacies changes in the overlying Katberg Formation.^{[11][12][13][14][15]}

Where the Balfour Formation deposits correlate with theDaptocephalus Assemblage Zone, a great diversity ofvertebratefauna are found. This richness in species diversity observed in the Balfour Formation is especially true ofdicynodonts as numerous different species of this successful,herbivoroustherapsid have been recovered.^[16][17] Various species ofburnetiamorphbiarmosuchians,rubidgeinegorgonopsians, andtherocephalianspecies such asMoschorhinus kitchingi and the earliestcynodont,Charassognathus gracilis, also appear.^[18]Parareptile species,^[19] namelycaptorhinids, theYounginiformeYoungina capensis,^[20][21] and a variety oftemnospondylamphibians,^[22] fishes, and plant fossils such asGlossopteris are likewise found.Glossopteris fossils or leaf impressions are particularly common in the Daggaboersnek Member. The uppermost unit of the Balfour Formation marks the Permian-aged side of thePermian-Triassic boundary. At this point in thebiostratigraphy there is a marked drop in species diversity as the Permian-Triassic extinction event began to take its course at the time of sediment deposition.

Genus	Species	Locality	Stratigraphic position	Time	Material	Notes	Images
Youngina	Y. capensis	Klipplaat, Doornplaas, Toverwater, Beeldhouersfortien, and Wellwood.	Dicynodon Assemblage zone.	Lopingian		Adiapsid reptile.

Genus	Species	Locality	Stratigraphic position	Time	Material	Notes	Images
Anthodon	A. serrarius			Changhsingian		A pareiasaur.
Milleropsis	M. pricei		Dicynodon Assemblage zone.	Changhsingian		Amillerettid parareptile.
Milleretta	M. rubidgei		Dicynodon Assemblage zone.	Changhsingian		Amillerettid parareptile.
Millerosaurus	M. nuffieldi			Changhsingian		Amillerettid parareptile.
Pareiasaurus	P. serridens			Wuchiapingian and Changhsingian.		A pareiasaur.
Owenetta	O. rubidgei		Cistecephalus and Lystrosaurus Assemblage Zones	Wuchiapingian and Changhsingian		A procolophonian parareptile.
Sauropareion	S. anoplus	Middleberg and Barendskraal Farm.	Lystrosaurus assemblage zone.	Induan.		A basalprocolophonid parareptile.

Genus	Species	Locality	Stratigraphic position	Time	Material	Notes	Images
Charassognathus	C. gracilis					Acynodont.
Cynosaurus	C. suppostus		Cistecephalus and Daptocephalus Assemblage Zones.	Wuchiapingian - Changhsingian.		A cynodont.
Procynosuchus	P. delaharpeae	New Bathsheba.		Wuchiapingian		A cynodont.
Progalesaurus	P. lootbergensis	New Lootsberg Pass.	Lystrosaurus Assemblage Zone.	Lopingian	A skull, dentition, and postcranial skeleton.	A cynodont.
Vetusodon[23]	V. elikhulu	Enyezane.	Daptocephalus Assemblage Zone.	Lopingian	A partial skull	A cynodont.

Genus	Species	Locality	Stratigraphic position	Time	Material	Notes	Images
Daptocephalus	D. leoniceps		Daptocephalus Assemblage Zone.	Changhsingian		Adicynodont.
Dolomitipes	D. accordii					Adicynodont.
	D. icelsi
Dicynodontoides	D. recurvidens	Nooitgedacht 68.	Uppermost part in Dicynodon Assemblage Zone.		A skull and postcranial element.	A dicynodont.
Emydops	E. arctatus					Adicynodont.
Lystrosaurus	L. curvatus	Nooitgedacht 68 and Fairydale.	lower part of Palingkloof Member, Dicynodon Assemblage Zone.	Induan.	A skull.	Adicynodont.
	L. declivis		uppermost part of Lystrosaurus Assemblage Zone.	Induan.	A skull and a complete skeleton.
	L. maccaigi		Palingkloof Member, Dicynodon Assemblage Zone	Changhsingian.
	L. murrayi		lower part of Palingkloof Member, Lystrosaurus Assemblage Zone.	Induan.	A skull and skeleton.
Oudenodon	O. bainii					A small dicynodont.

Genus	Species	Locality	Stratigraphic position	Time	Material	Notes	Images
Aloposaurus	A. tenuis					A gorgonopsid.
Cyonosaurus	C. kitchingi					A gorgonopsid.
	C. longiceps
Dinogorgon	D. rubidgei		Cistecephalus and Daptocephalus assemblage.			A gorgonopsid.
Inostrancevia[24]	I. africana	lower slope of the hill Loskop, Nooitgedacht 68.	Daptocephalus Assemblage Zone		A partial skeleton including a complete skull and occluded mandible, entirety of the precaudal axial column, partial scapulae, partial right pelvis, the right femur, and a disarticulated left humerus, ulna, radius, and tibia.	A predatoryinostranceviinaegorgonopsid.
Leontosaurus	L. vanderhorsti		Dicynodon Assemblage Zone.			A gorgonopsid.
Lycaenops	L. ornatus					A gorgonopsid.
Paragalerhinus	P. rubidgei	Wellwood	Dicynodon Assemblage Zone.		A partial skull.	A gorgonopsid.
Rubidgea	R. atrox		Cistecephalus and Daptocephalus assemblage zone.			A gorgonopsid.
Scylacops	S. capensis					A gorgonopsid.

Genus	Species	Locality	Stratigraphic position	Time	Material	Notes	Images
Ictidochampsa	I. platyceps		Dicynodon Assemblage Zone.			Atherocephalian.
Ictidosuchoides	I. intermedius					Atherocephalian.
Ictidosuchops	I. intermedius					Atherocephalian.
Moschorhinus	M. kitchingi	Spitskop, Nooitgedacht 68.	Dicynodon Assemblage Zone.		A weathered skull along with a complete skull, partially articulated anterior skeleton, and disarticulated pelvis and hind limb.	Atherocephalian.
Notaelurodon	N. kitchingi					Atherocephalian.
Olivierosuchus	O. parringtoni	Palingkloof Member	Lystrosaurus assemblege zone.		A complete skull and anterior half of skeleton in articulation, including vertebrae, ribs, pectoral girdle, partial left humerus, complete right forelimb, including terminal phalanges.	A therocephalian.
Promoschorhynchus	P. platyrhinus					Atherocephalian.
Theriognathus	T. microps					Atherocephalian.
Tetracynodon	T. tenuis					Atherocephalian.

The Balfour Formation is known to corresponds in age with theCis-Uralian fauna ofRussia^[25] and theSanga do Cabral Formation,Paraná Basin ofBrazil. Correlations with other LatePermian - EarlyTriassic deposits abroad remain inconclusive.

• Geologic formations of South Africa
• Permian System of Africa
• Permian South Africa
• Sandstone formations
• Shale formations
• Deltaic deposits
• Beaufort Group
• Carboniferous southern paleotemperate deposits
• Permian southern paleotemperate deposits
• Lagerstätten
• Fossiliferous stratigraphic units of Africa
• Paleontology in South Africa
• Geography of the Eastern Cape
• Geography of the Northern Cape
• Geography of the Western Cape

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