Tectonic Plates Continetal Drift Namibia
It was as early as 1620 that the English philosopher Francis Bacon commented on the apparent similarity of the shape of the West coastline
TECTONIC PLATES. An interesting history. It was as early as 1620 that the English philosopher Francis Bacon commented on the apparent similarity of the shape of the West coastline of…
Tectonic Plates Continental Drift Gondwana and Namibia
It was as early as 1620 that the English philosopher Francis Bacon commented on the apparent similarity of the shape of the West coastline of Africa and the Eastern coastline of South America. However, Bacon made no reference that the two continents could have once been joined. In 1858, an American called Antonio Schneider made the suggestion that the continents had somehow moved in respect to each other. But, it was not until 1915 that German meteorologist Alfred Lothar Wegener (1880-1930) published in his book, 'THE ORIGIN OF CONTINENTS AND OCEANS' the theory of Continental Drift . Wegener proposed that the earth had once consisted of a single land mass surrounded by a vast ocean. He named this super continent Pangaea and explained that it had long ago divided forming two great continents - Laurasia in the North and Gondwana in the South and that, in time, these two continents had further divided.
Wegener's theory was viewed with scepticism by the Geological fraternity until the 1960s by which time advanced scientific measuring equipment had been developed and the phenomenon of Paleomagnetism was accepted.
The Paleo-Maps shown below cover a period beginning 650 million years ago showing the development of the land masses beginning with the ancient continent of Rodina and continuing through to 50 million years in the future, showing, where it is thought the land mass of Africa, and Namibia, will be situated should tectonic plate movement continue at the present rate.
Between 4,000 and 2,500 million years ago the early tectonic plate movements in the earth's crust began to form the first land masses. In southern Africa the Kaapvaal Craton stabilized as long ago as 3,000 Ma, and the Zimbabwe Craton had stabilised by 2,600 Ma. By 1,300 Ma ago these two Cratons had connected with the Congo and Kalahari Cratons , and the land mass known as Rodinia was beginning to form.
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.
Tectonic plate 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.
1. Ediacaron Period . 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.
2. Early Carboniferous Period . 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 was moving into the beginnings of an Ice-Age.
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.
5. Early Jurassic Period : 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
6. Late Jurassic Period : 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.
8. K/T Boundary . The bull's-eye marks the point where the extra terrestrial body, which is estimated at having been some 10 mile in diameter impacted with the earth some 66Ma ago and is thought to have been responsible for the extinction of the dinosaurs and many other life forms of the time. By the late Cretacious Period the ocean separating the continents of Africa and South America was of a considerable width, and the island of India was moving towards southern Asia. The word Chicxulub in the Mayan language means, "the tail of the devil". The impact crater was discovered as recently as 1970 by geophysicist Glen Penfield while doing research in the area for oil.
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
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