Geological Time Scale Namibia
Between 4,000 and 2,500 million years ago the early plate tectonic movements in the earth's crust began to form the first land
Between 4,000 and 2,500 million years ago the early plate tectonic movements in the earth's crust began to form the first land masses. In southern Africa the Kaapvaal Craton stabilized…
Geological Time Scale and Namibia
What's in a name: Gondwana derives its name from an area situated in Central India, meaning Land of the Gonds, where a 'tribe' of people known as the Gonds lived. Also in this area of India is a geological feature that was formed in the early Palaeozoic to early Mesozoic eras and is referred to as the Gondwana Beds. During the latter part of the nineteenth century the Austrian geologist Edward Suess, suggested that, on the basis of comparative geological evidence, the continents of Africa - Australia - India and South America had once formed a super continent which he named Gondwana . OK, so if one 'says' Gondwana, it literally means Land of the Gonds Land, or Gonds-Land Land. It would appear that Gondwana is the more correct of the two.
Plate-tectonic movement caused the land mass to increase and also move southwards that by the Early Cambrian Period some 500 million years ago Gondwana had grown into a great continent comprising of what is now referred to as Africa - Antarctica - Australia - India - Madagascar - South America - and at one time even included the American State of Florida and part of Southwest Europe, with the southern areas straddling the polar region. From 320 to 270 million years ago the Great Gondwana Ice-Age covered Namibia. Glaciers scoured the ancient rock formations and during the melt floods moved enormous amounts of boulder debris and sediments that in places would settle to be thousand of metres thick . During this time the great inland Gai-As sea covered much of southern and western Namibia and spread into what is now South America. The discovery of Mesosaurus fossils in both Brazil and Namibia have helped to support the theory of Continental Drift . There were later times when vast deserts covered much of Namibia and extensive volcanism. Gondwana began to break about 130 million years ago and the two new continents of Africa and South America began to drift apart. See the below Paleo Maps created by Christopher R. Scotese for a better understanding of the earth's plate movements from 650Ma ago and into the future 50Ma to see an equatorial Namibia.
The Air That We Breath: The oldest known of fossils in the world are of the green-blue algae known as cynobacteria that lived at the edges of the ancient oceans as early as 3,500 million years ago. These simple algae increased to be the dominant life force on the planet for most of the Eon of time known as the Proterozoic, and derived their energy from the sun's rays by the process of photosynthesis. 3,000 Ma ago the earth's atmosphere was rich with carbon dioxide and devoid of oxygen, but over a period of 1 billion years the activity of these small algae had increased the atmosphere's oxygen content to about 20% which in turn allowed for more complex life forms to evolve. These algae with their glutinous sheaths as protection grew in colonies and carpeted the sea bed. Grains of sand would cling to the sheath's and eventually block the sun's light from them. The algae's survival response was that of growing up through the layer of grains in order that they could continue with the process of photosynthesizing. This pattern of early life continued over hundreds of millions of years and eventually led to the building of the great carbonate mountain chains. The fossilized remains of these algae 'constructions' are named Stromatolites and represent the some of the oldest of all fossils, and can be found in Namibia.
The Super Continent of Rodinia began to form 1,100 million years ago, and by the Late Neoproterozoic (650 million years ago) it was starting to divide into the land masses that would become known as Baltica and Laurentia, with Gondwana positioned in the southern latitudes.
Namibia: The Otavi Mountain lands were formed (stromatolites and oncolites) by algae growth along with early marine life deposits that laid to depths of up to 5 kilometres. The fossilized Stromatolites and Oncolites that can be found in the area are between 830 to 760 million years old.
Early Carboniferous: The super continent of Pangaea began to form as the Palaeozoic oceans between Euramerica and Gondwana began to close. The ice cap at the south polar region grew, and the vertebrates being fish evolved while on the land plants were the dominant life form.
Namibia: As the southerly parts of the super-continent moved further south he ice cap was moving northwards and ice sheets were beginning to form across southern Africa.
Namibia: was near to the South-Pole experiencing the ' Dwyka' Ice-Age that lasted from 320 to 270 million years ago. Glaciers scoured the land's rocky surface as they moved to the sea carrying rock debris with them. As the Ice-Age ended the sea level rose. Sediments were deposited on the 'Dwyka" rocks. Mud-stones and shale beds were formed. Fossils of this period that have been found in Namibia are those of ancient fish and shell fish. Glossopteris plants were spreading along the banks of rivers and delta
Namibia: The great lake Gai-As covered an area stretching from the Karoo in South Africa across southern Namibia ( Karasburg - Keetmanshoop ) and into what is now Brazil. The first land reptiles to return to the water were Mesosaurus and they swam in this great inland sea. In the north of Namibia there were great forests of Cordaites trees similar to those that can be seen at the Petrified Forest .
Triassic Period: The Archosaurs dominated the food chain and were the ancestors of the Dinosaurs, modern day crocodilians , and birds.
Early Jurassic: South-East Asia moves northwards and The Great Tethys Ocean separates the 'new' northern continents from Gondwana . On land the Dinosaurs were beginning their rule across Pangaea.
Namibia: The ancient rocks of the Omingonde Formation were beginning to be covered over by the deposits know as the Etjo Formation. Early dinosaurs such as the Ceratosauria that left their tracks at Otjihaenamaparero and Massospondylus that left its tracks on top of the Waterberg Plateau wandered
Namibia: The Etjo Formation was being deposited on top of the Omingonde Formation
Late Jurassic: The super continent of Pangaea began to separate in the Middle Jurassic period. By the Late Jurassic the Central Atlantic Ocean was between the north west African coast and the eastern seaboard of North America.
Namibia: Is part of great desert that covers most of Gondwana
Namibia: The Mesosaurus fossil finds in eastern Brazil and southern Namibia played an important role in helping to prove the theory of Continental Drift.
Namibia: It appears that Namibia will experience a dryer climate and increased desert areas. The new 'Buzz-Word' is Global Warming.
The continents are once again drifting together and a new Pangaea will eventually be formed.
Plate tectonic maps and Continental Drift animations by C.R. Scotese, PALEOMAP Project. (www.scotese.com)
Each of the Eons is divided into Eras , which in turn are sub-divided into Periods and then into Epochs.
As stated above, early life began in the seas about 3,500 million years ago in the Archean Era, but it was not until the Paleozoic Era, about 570 million years ago that a profusion of marine invertebrates developed such as cephalopods, corals, gastropods, trilobites and worms. The early fish were invertebrates having their bodies within 'armour casings'. The first vertebrates appeared about 500 million years ago and fish evolved into creatures having a bone skeletal frame and became the dominant vertebrate. About 410 million years ago certain species of fish developed into amphibians and began to colonize the land. It was about 360 million years ago that the early reptiles evolved and they in turn began to displace the amphibians as the dominant land species.
Note: The time scale used is as determined by the International Committee on Stratigraphy (ICS)
3 Ma: Karstification Carbonate Rocks - Otavi Mountains - Gaub Cave Naukluft Mountains
In Namibia: 750 Ma: Third mountain building phase. Folding of the Damara Granites. Auas, Naukluft. Formation of the Otavi Mountains by marine deposits
In Namibia: 1,000 Ma: Land erosion, Luderitz Peninsula, Khomas Hochland
In Namibia The Epupa, Grootfontein and Huab Metamorphic Complex were formed
Acknowledgements and further reading: E1, E2, G1, G2, G3, M2, W1, W2
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