Croeser Synoptic Table Geological History Last 500M Years
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A synoptic table of the geological and life history of the past 500 million years, with particular focus on southern Africa and KwaZulu-Natal. Compiled by Peter Croeser, Natal Museum, Pietermaritzburg,1998. P E Millions E EPOCH ROCK STRATIGRAPHY CLIMATE AND EARTH HISTORY DOMINANT ANIMALS AND PLANTS R of years R GROUPS A ago I O D Present The Holocene is dominated by the last Ice Age which Modern man, Homo sapiens sapiens, finally emerges some 200 covers much of northern Europe, Asia and North 000 years ago in either southern or eastern Africa. Some 110 000 America with glaciers and permanent snow starting years ago, during the onset of the last Ice Age, modern man about 110 000 years ago and ending abruptly 11 500 HOLOCENE begins leaving Africa into Europe and the Middle East across land C years ago (within the space of about 70 years). bridges formed by low sea levels. The abrupt ending of the Ice Age and the onset of warmer, wetter conditions than the present sees E Q During the Ice Age sea levels are about 6 metres below the emergence and development of pastoralism, agriculture, and present levels. urbanisation by modern humans. U N 0.11 A Maputaland Group In Durban, coastal sand dunes became consolidated to During the mid Pleistocene the climate in Natal was warm to dry, • Berea Red Sand (red form the sandstone cliffs of the Durban Bluff, while red but lower-lying areas supported a rich fauna. Larger animals O T decalcified sands) sand dunes further inland formed the ridges on which included now extinct species of buffalo, elephant, rhinoceros and the Durban Berea is built during the middle to late hippopotamus whose fossilized bones together with petrified wood, Z PLEISTOCENE • Durban Bluff Pleistocene (700 000 to 100 000 years ago) are found at Port Durnford. E Sandstone O During the Pleistocene sea levels rose to their present During the early Pleistocene, Australopithecus died out (about one R level and have remained there for the past 4 million million years ago) and Homo erectus, similar in size to modern years, with only small variations of about 6 metres man, became the dominant early man species, spreading from N either way. Africa into Europe and Asia. I 1.8 At the end of the Pliocene, parts of Natal were raised by Towards the end of the Pliocene Australopithecus, crouched and A upto 180 metres above sea level (either by dropping only 1,4 metres tall, co-existed with stone-tool-making man (Homo C seas or by movement in the earth's crust). The seas habilis and erect-walking Homo erectus). R over Zululand drained off the land, turning the earlier Pliocene seabed into the coastal lowland plains we During the Pliocene, ancestors of the mammals we know know today. The sea retreated to some 60 metres Y today were abundant and Africa became the birthplace of PLIOCENE below the present sea level. The dunes formed at the man. edge of the sea during this stage are now a line of reefs a kilometre or so off the coast of Zululand from Black The oldest fossilized remains of early, small-brained man Rock to Mtunzini. (Australopithecus) date back some three million years ago and were found in eastern and southern Africa. During the early to mid Pliocene the sea levels steadily rose to some 50 metres above present levels, once again isolating Table Mountain from the mainland and Corals, sharks and tropical shells and fish were abundant in the covering the low-lying coastal plains of Zululand for the shallow, warm sea that once more covered low-lying areas of last time. Zululand. 1 P E Millions E EPOCH ROCK STRATIGRAPHY CLIMATE AND EARTH HISTORY DOMINANT ANIMALS AND PLANTS R of years R GROUPS A ago I O D 5 At the end of the Miocene (between five and six million At the end of the Miocene, when the Mediterranean basin dried up, MIOCENE years ago) sea levels dropped sharply, the climate many ancient Asian mammals entered Africa for the first time became increasingly dry, deserts grew and the including the elephant family, many antelope, hyaenas and sabre- Mediterranean basin dried up. toothed cats. During the mid Miocene the climate was warm and wet as Africa moved northwards over the Equator and tropical forests covered the middle of Africa. A During the Tertiary, mammals, no longer suppressed by dinosaurs, C T longitudinal bulge developed down east Africa and then diversify and flourish and become dominant on land. Flowering collapsed to form the Rift Valley. Interrupted rivers plants spread rapidly and grasslands develop. E E drained internally to form the great lakes of central and east Africa. N R The early to mid-Miocene shallow, warm seas covering lower-lying During the early Miocene, sea levels rise once again to Zululand support more than 100 species of shellfish and giant O T isolate Table Mountain from the Western Cape and sharks (like Carcharodon megalodon). The fossilized remains of warm, shallow seas cover the low-lying Zululand plains these extinct animals, including nearly 12 cm long sharks' teeth Z I from Port Durnford to the wide Maputaland plains of and species of Pecten (shells resembling the Shell Petrol logo), are Zululand and Mocambique. found from Richards Bay to Uloa on the Mfolozi River. O 23 A OLIGOCENE I 38 R EOCENE C 54 Y PALAEOCENE 2 P E Millions E EPOCH ROCK STRATIGRAPHY CLIMATE AND EARTH HISTORY DOMINANT ANIMALS AND PLANTS R of years R GROUPS A ago I O D 65 Uitenhage At the end of the Cretaceous sea levels drop rapidly to The fifth and last mass extinction of plant and animal life was at Group well below present levels, exposing land bridges linking the Cretaceous-Tertiary (K-T) boundary at the end of the C North America with Europe and Asia, southern Asia with Cretaceous period. Inhabitants of the shallow, warm seas that Zululand Australasia and Africa with Europe. covered continental lowlands around the world for much of this M R Group period, died out as sea levels dropped to the cold deep-sea *St Lucia continental margins well below present sea levels. On land E E Siltstone migrations of animals and plants along the newly exposed land bridges between the continents led to the introduction of new S T diseases while ecological systems disturbed by the new invaders For much of the Cretaceous period the world climate is collapsed or changed, leading to the extinction of many plants and O A warm and sea levels much higher than at present, animals dependent on them. The final blow may have been struck creating shallow warm seas over most continental by a giant meteorite colliding with the Earth. A thin dust layer of a Z C lowlands. The lower-lying Zululand plains and southern metal, Iridium, commonly found in space asteroids and meteorites Mocambique are covered by sea which also isolates the but rare on Earth, has been found in various parts of the world in O E Table Mountain range from the Western Cape mainland rocks formed at the end of the Cretaceous period. Among groups and covers much of the Eastern Cape coastal plain. In that did not survive were the giant spiral-shelled ammonoid cuttle- I O North America shallow seas cover the eastern and fish and the dinosaurs, except for birds. central lowlands from the foot of the Rocky Mountains C U to the Appalachians. The Cretaceous was a period rich in animal and plant diversity. The first snakes developed from burrowing lizards and birds such as S waders, cormorants and owls evolved and shared the skies with the pterosaurs. In North America dinosaurs flourished around the rich, shallow inland sea and included the well-known plant-eaters Triceratops and the duck-billed hadrosaurids (eg. Parasaurolophus and Corythosaurus) and meat-eaters such as Tyrannosaurus and Stenonychosaurus. 142 Karoo Jurassic weather was warm and wet and while animals In the late Jurassic the giant sauropod plant-eating dinosaurs J sequence and plants flourished in most parts of the world, major appeared: Apatosaurus (21 m long) in North America, Cetiosaurus M changes were taking place in Gondwanaland. (18 m long) in north Africa, Brachiosaurus (25 m long, 16 m high, U 50 tons) in east Africa as did large predators like Megalosaurus (9 E • Gondwanaland began tearing apart and the m long) in South America, Asia and probably Africa. Small 183 R Drakensberg Basalt volcanic activity that ensued saw the Stormberg theropod dinosaurs gave rise to the first birds, plants flourished and S Group lavas (forming the Drakensberg basalts) flood the there were thick forests. A (= Upper Stormberg) Karoo Basin destroying all of its terrestrial life O • Drakensberg Basalt between 165 and 183 million years ago. The Living in southern Africa during the early Jurassic was one of the S Formation Lavas weakening and flexing of the African continental smallest true dinosaurs, Lesothosaurus (1 m long), from Lesotho, a Z plate in southern Africa leads to magmatic dolerite plant-eater about the size of a small Alsation dog, which ran on its S intrusions in the form of vertical dykes and long, slender hind legs. Larger two-legged southern African O horizontal sills (such as the flat dolerite platform on predators included Syntarsus (3 m long) from Zimbabwe. Small I which Howick rests, cut by the Umgeni plunging rodent-like mammals, flying pterosaurs, crocodiles, reptiles and I down the Howick Falls). amphibians were amongst the other land animals. Plants included C • present coastline forms very tall conifers with true cones, cycads, tree ferns and horsetails.