The Uitenhage Group is one of three geological groups, which comprise the onshore and offshore post-Karoo middle to lower UpperMesozoic geological rock units in South Africa. Stratigraphically, the Uitenhage Group overlies the Suurberg Group and is overlain by the Algoa Group. It contains four formations that range in age from late Early Jurassic and late Early Cretaceous in age.
In the onshore part of the southern Cape, deposits of the Uitenhage Group occur predominantly in the Algoa and Gamtoos Basins, which are situated north/north-west of Port Elizabeth in the Eastern Cape, South Africa. Smaller deposits also occur in the Baviaanskloof, Georginda, Vlakteplaas, Oudtshoorn, Plettenberg Bay, Knysna, Herbertsdale-Mossel Bay, Heidelberg-Riversdale, Swellendam, and Worcester-Robertson Basins. These are grabens and half-grabens that opened up due to mainly normal faulting processes during the break-up of Gondwana.
Enon Formation: Contains subordinate sandstones and different types of thickly-bedded conglomerates, which consist mainly of quartzite and sometimes slate, shale, and charcoal. The clasts are poorly-sorted, sub-rounded to rounded pebbles and cobbles. Deposition occurred mainly in high-energy alluvial environments.
Kirkwood Formation: Contains mainly medium-grained sandstone that is locally charcoal-rich, sporadic conglomerates, and variegated mudstone. Out of the three formations of the Uitenhage Group, the Kirkwood is the most well-studied, and is extremely fossil-rich. Deposition occurred under mainly fluvial conditions at or near sea level.
s are especially common in the Kirkwood and Sundays River Formations, although regarding the Sundays River Formation the most common fossils are of invertebrates. Past expeditions within the Kirkwood Formation have uncovered several dis-articulated remains of theropod, sauropod, and ornithopod dinosaurs, and a plesiosaur fossil is known from the Sundays River Formation. Fossil remains of amphibians, lizards, fishes, and small mammals have also been recovered. A variety of bivalve, gastropod, ammonites, and ostracods are likewise known from these deposits. The fossil flora is equally diverse and silicifiedtree trunks - some with evidence of being charred by fire - have also been found.
