Curious Continents (Geography has still a lot to discover)

A recent tweet has inspired some curious fact-finding.

It shows that there is little dry land on Earth where the antipodes are dry land as well, instead of just ocean. This can be explained at least partially by there being only 29.2% of land.

In theory then, every piece of land has only 29.2% chance of being a place where “if you drill through the globe, you’ll hit land on the other side” (as written by a commenter on Twitter to describe the situation very briefly). However, since the land is concentrated in huge continents the actual number is likely smaller.

For example Africa covers 20.3% of the Earth’s land, i.e. 5.9% of the total surface. The simplified chance of finding land on the other side of Africa is therefore (remaining land)/(ocean surface+remaining land), i.e. (29.2-5.9)/((100-29.2)+(29.2-5.9))=22% (this is because Africa cannot be at its own antipodes).

End of story? Not quite. A comprehensive look at the situation reveals it as full of tantalizingly curious details.

The world and its antipodes

The picture above (click to enlarge -hope it’s clear enough even if a bit rough!) uses transparency to show what’s on the other side of the world (original Mercator projection by Google Maps -used here as I’m interested in directions – the map by Amazing Maps uses the Peters projection instead).

Among the amazing peculiarities:

  1. Australia seems cut out of the lower North Atlantic ocean. Its coastline follows the contours of the eastern US coast, then the coasts of Venezuela, the Guyanas and Brazil, and even partially the western coast of Africa
  2. Likewise North America has the perfect shape to fit in the Indian Ocean, roughly following the south-eastern coast of Africa and then curving as if to “avoid” Australia
  3. The northern coasts of Russia and Alaska eerily follow (on the other side of the world) the same path as much of the coast of Antarctica: what is land to the north is ocean in the south, and vice-versa
  4. The antipodes of Africa and of most of the Eurasian continent sit comfortably in the Pacific ocean. Europe manages to just touch New Zealand, and only partially so (mostly, this concerns the volcanic northern island of NZ)
  5. The entire path of India’s migration from Madagascar to the Himalayas is antipodal to and follows the contour of the ocean to the west of Mexico
  6. The odd ones out are (a) the area of Chile and Argentina, corresponding to central China and eastern Mongolia; (b) the Antarctic Peninsula, just to the south of Chile and Argentina and jutting towards them and (c) Greenland and the Canadian Archipelago
  7. Note also that almost exactly on the other side of the narrow strip of land known as Central America, there is the elongated archipelago known as Malaysia and Indonesia.

If confirmed with a more accurate map, my impression would be that there is a hitherto-hidden physical law at play here. It seems that continents cannot simply hang about at random locations, and their place in the Big Schema of the Planet depends on something that has been overlooked until now.

For example, consider that Pangea was constituted 300 million years ago and began to break up 200 million years ago. Now, if we reduced 100 million years to just one year, Earth would be spinning at more than 1,000 revolutions a second. From the point of view of a continent, our planet is like a centrifuge. This has to have its consequences.

 

12 Replies to “Curious Continents (Geography has still a lot to discover)”

  1. There is going to be an an article about it at the Journal of Indian Geophysical Union, volume 22. No 1, 2018, pp. 60-65.

    1. “On the global aspects of the almost-antipodal symmetry on the Earth”
      Kovalyov, Mikhail

      Would you have a preprint?

      Thanks!

  2. There is a specific reason why the antipodes of continents/continental shelves have similar boundaries. It is not the same as the similarity of continental/continental shelves boundaries in Continental Rift. But until recently it has been overlooked.

  3. That the coastlines of the continents fit each other very well, and even more so if the continental shelfs are taken into consideration, was observed by the german engineer Ott Christoph Hilgenberg in his booklet “Vom wachsenden Erdball”, Berlin 1933. Therein he described how he crafted globes of smaller size until the continents fitted the surface perfectly. If my memory serves me, a near perfect fit is possible when the globe had around 60 percent of todays diameter.

    1. Hugo – to be 100% clear – I am moving the idea to a different level. I am saying that continents are where they are because the interact with each other even at the antipodes, so that eg the Australian coast is constrained by the position of the African and American coasts.

      This is helped by the fact that, from the point of view of a continent, the planet is turning around extremely fast.

      1. You do not consider that in the geologic past the position of the continents was completely different. The current positions are not in equilibrium in any sense you would assign them.
        It’s just coincidence.

      2. Any coincidence showing to people who live decades but pertaining to processes lasting millions of years is worth noticing

        Besides we ought check if the coincidence happened beforehand as well. Did Pangea (which followed the antipodal ocean rule) break up more or less at once?

  4. Now – Now ! Easy does it. Fun, but surely nothing more than coincidence. Keep in mind that a man named Wegener once tried to make something out of the fit of the coastlines of Africa and S. America, and everyone at the time knew how silly that was. Egg on his face! The experts were in agreement – a consensus. Without “experts” how would our imaginations be properly constrained?

  5. This is fascinating stuff. Probably a clever design feature by Slartibartfast, when he was drawing up the blueprints (see HHGG), although the mismatch of South America/China, etc. suggests a rush job – maybe he had devoted a bit too much time to the Norwegian fjords.

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