| Sundays River Formation | |
|---|---|
| Stratigraphic range:Valanginian-Hauterivian ~139–131 Ma | |
 Sandstone layer overlying siltstone/mudstone | |
| Type | Geological formation |
| Unit of | Uitenhage Group |
| Underlies | Algoa Group |
| Overlies | Kirkwood Formation |
| Thickness | Up to 2,000 m (6,600 ft) |
| Lithology | |
| Primary | Sandstone,claystone |
| Other | Siltstone,mudstone |
| Location | |
| Coordinates | 33°36′S25°36′E / 33.6°S 25.6°E /-33.6; 25.6 |
| Approximate paleocoordinates | 45°06′S11°30′W / 45.1°S 11.5°W /-45.1; -11.5 |
| Region | Eastern &Western Cape |
| Country | South Africa |
| Type section | |
| Named for | Sundays River |
 Map showing extent of the Sundays River Formation in the Algoa Basin | |
TheSundays River Formation is a geologicalformation found in theEastern andWestern Cape provinces inSouth Africa. It is the second youngest of the four formations found within theUitenhage Group of theAlgoa Basin, its type locality, and the only location where outcrops have been located. The Sundays River has been measured at a maximum thickness of 2,000 metres (6,600 ft).[1]
The Sundays River Formation overlies theKirkwood Formation which it grades laterally into in certain areas, meaning that they correlate in age in some localities.[2][3] Thesedimentary rock of the Sundays River comprises mainly fine to medium grained greysandstones which often contain shell fragments,siltstones, andmudstones. The sandstone layers are frequently cemented withcalcite layers. These were deposited in a shallowmarine environment which likely includedestuarine andlagoonal settings.[4][5]
The Sundays River is highlyfossiliferous and a variety of fossilflora andfauna have been discovered.Invertebrate shells fromammonites,bivalves, and microfossils such as species offorams andostracods[6] are commonly found cemented within thecalcite layers in the sandstone deposits.[7][8][9]Trace fossils ofgastropod tracks which are infilled withsiltstone are also frequently found.[10][11] Somevertebrate fossils have been found, most notably a near-complete skeleton of a marineplesiosaur,Leptocleidus capensis.[12] However, very little study has been done on the plesiosaur specimen discovered here. Plant remains[13] and non-diagnostic vertebrate fossils have also been recovered.[14]
Color key
| Notes Uncertain or tentative taxa are insmall text; |
| Plesiosaurs of the Sundays River Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
| Leptocleidus | L. capensis | Aleptocleididplesiosaur | ||||
{{cite journal}}: CS1 maint: multiple names: authors list (link){{cite journal}}:Cite journal requires|journal= (help)
