Lesson Plan - Get It!
- Have you ever heard this term before?
Alfred Wegener gave the name Urkontinent to a single land mass on the face of the Earth in early geologic time.
Wegener was a German polar researcher, geophysicist, and meteorologist who combined many geologic studies to devise a theory in 1912 about how the continents drifted apart.
- How did he know that the present continents were once joined together and separated over time?
- Are these continents still moving away from each other?
These and many other questions are the subjects of your exploration today!
You are likely more familiar with the term Pangaea.
Pangaea was the name given to a supercontinent that existed millions of years ago. Like any geologic formation, its evolution is evident.
Therefore, several names were coined to distinguish each of its evolutionary forms -- Kenorland, Columbia, Rodinia, and Pangaea. In fact, even the future fate of the continents has its own name -- Amasia.
This lesson will be an exciting feat of geologic history at its finest!
The Continental Drift Theory
The theory of continental motion started about 1912 when a scientist named Alfred Wegener began analyzing old and new data about the position of the continents on the face of the Earth during the Paleozoic era.
The Paleozoic era is an age of major change on Earth where continents started moving apart and combining about 540 million years ago. He called it Urkontinent, later changing it to Pangaea, which means all earth.
Watch an animated documentary about the adventures of Alfred Wegener, produced by The New York Times.
Animated Life: Pangea | Op-Docs | The New York Times:
Wegener named this collection of studies the continental drift theory, which became the basis of the plate tectonic theory widely accepted at the present time.
However, it wasn't easy for Wegener because many geologists soundly denounced his theory after he published the details in a 1915 book called The Origin of Continents and Oceans. These geologists asserted that Wegener did not have sufficient evidence or even models to explain how pieces of the land moved.
While Wegener's observations about fossils and rocks that existed in each of these continents are correct, there were many parts of the theory that were proven inaccurate.
One of these hypothesized that the continents might have plowed through the ocean crust like icebreakers smashing through the ice. This idea was obviously proven wrong.
Regardless of inconsistencies, Wegener laid down the foundation for what we know about the Earth's geologic features and behaviors.
A supercontinent is a single land mass formed by the combination of multiple continents.
There is no detailed map that shows exactly how this supercontinent was before it split into separate continents, which then moved. However, the latest map of Pangaea provides more clues.
- What are the widely recognized supercontinents of the earth?
This sounds like a modern name for an adventure island. Kenorland is one of the earliest supercontinents, thought to have formed some 2.4 billion years ago.
The belief is that it formed from a deep mantle plume rifting that caused a rapid circulation of materials from the hot core of the planet to the cool surface and back again.
The core of Kenorland came together around the junction of Laurentia, Baltica, Western Australia, and Kalahari. You can see an approximation of Kenorland, courtesy of The Dialogue.
This familiar-sounding supercontinent called Columbia was proposed in 2002 by John Rogers and M. Santosh.
The name was coined due to the fact that the best evidence for its existence is in the Columbia River region of western North America, which was supposedly connected to eastern India at the time of this supercontinent.
The formation of this supercontinent was a result of an early amalgamation of most of the world's continents into one vast land area that later split up, reformed, and divided several times, shaping the Earth's current continents.
The Dialogue provides this approximation of Columbia.
The name Rodinia is a Russian word meaning homeland.
It is believed to have formed about 1.2 billion years ago when fragments of continental crust, pushed together by plate tectonic motion, began to assemble a giant continent.
Evidence suggests that the east coast of present North America was probably adjacent to western South America. The west coast of North America lay next to what is today Australia and Antarctica.
It also believed that Rodinia is the beginning of all the present continents, and that the first complex animals evolved in the coastal seas around it. The Dialogue shows how Rodinia appeared from the South Pole.
The latest among the supercontinents, Pangaea has provided more evidence of its existence due to more sophisticated research and data that could support it.
Its name was derived from the Greek word pangaia which means all the earth. It appears to have formed some 300 million years ago and broke apart during the Triassic time.
Pangaea broke apart into two very large continents, Laurasia in the north and Gondwana (or Gondwanaland) in the south, separated by the Tethys Sea. These later separated into the continents we know today.
Check out The Dialogue's depiction of Pangaea.
The image below shows a timeline of all these supercontinents:
Image [created with crops from the original] by SimplisticReps, via Wikimedia Commons, is licensed under the CC BY-SA 4.0 license.
Watch The Super-Continents Before Pangea from KnowledgeHub:
If you want to learn even more, you can check out these resources:
The Future Fate of Continents: Amasia
Geologists treat the continental movement as continuous and cyclical.
If the continents continue to move at their present rate, North America and Asia will converge and form the fifth supercontinent in about 50 million to 200 million years.
Africa is already on its way to Europe, closing the last remnant of the Tethys that we know today as the Mediterranean Sea. Australia is currently moving northward toward Asia. Antarctica would follow, and the Atlantic Ocean will expand into a new Panthalassa.
While this will not happen in our lifetime, it is an amazing prospect for the future. You see, everything is temporary. The only constant thing in this world is change.
The idea that all the continents of the world were once joined together is truly remarkable. It raises more questions about how humans and early life forms are connected to each other and changed over time as they adapted to environmental conditions.
In the Got It? section, you will test your knowledge about the supercontinents!