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Why Do Most Peninsulas Point South?

Do most peninsulas point south - or do they just appear to?

Q: Why do most peninsulas on the globe point south?  From the southern continents to Scandinavia, Italy, Iberia, all seem to point in a southerly direction.  Is there a geological explanation of this striking fact?

From Mr Ernest J Speed, Wokingham (July 2009)

Ted Nield

Reply by Dr Ted Nield (Editor, Geoscientist)

Thank you for your interesting inquiry about the apparent tendency of continents to taper, and peninsulas to point, south.

It is a fascinating question, which I can see raises all kinds of different explanations, from geology to cognition, human psychology, cartographic conventions and even fractal geometry. Most of these subjects I am not in the least qualified to comment upon; but all of them, I suspect, have some bearing on the answer.

Let us start with the southern continents and their southerly taper. The former southern supercontinent Gondwanaland, began to split up about 250 million years ago and gave rise to wedge-shaped pieces like segments of a pie. This was because the cracks in Gondwana tended to follow intersecting courses. This is not hard to understand, since when objects crack their fractures are dominated by geometry. Cracks in dinner-plates are usually radial, and cracks in a continental lithospheric plate on a globe will similarly follow great circles.

This break-up created the present continents of India, South America and Africa, all of which then drifted away from each other; preserving, however, their general orientation, i.e., with the “point” directed to the South Pole. (It is worth noting at this point that this break-up also created Australia which, to my eyes at least, “points” north rather than south!)

We should leave aside what we define as a “peninsula” since coastlines are governed by fractal geometry, and there is no end to their complexity. Our human decision to look at them at a certain scale - of one to a million or ten million - is arbitrary, and the patterns we will see at one scale may be different at another. Take Scandinavia, for example. It falls, as a whole, into your definition of a south-pointing peninsula, but at the scale of a road-map, is dominated by east-west peninsulas separating the fjords.

But, leaving that aside, "peninsulas" (however defined) can have no single geological explanation, since they all have different geological structures and in any case are only “expressed” as peninsulas on the current globe by virtue of the modern relative height of the oceans (relative, that is, to land). This relationship has varied widely through geological time.

So, in dealing with peninsulas, questions of scale, definition, convention and of human cognition and perception, assume an important role. Denmark and Cotentin (Northern Normandy, France) could be cited as exceptions to the southerly “rule”. There are many more. The Cape York Peninsula and Arnhem Land (Australia) I have referred to already. The north coast of Russia boasts several, including the Kola. If sea level were lower, then not only would Novaya Zemlya be a northern "pointing" penisula, but so would the UK! Then there’s Ogaden (the Horn of Africa) the part of the Emirates and Oman that sticks into the Straits of Hormuz, Qatar (Arabian Gulf) Yucatan (balancing southerly-pointing Florida), Graham Land (Antarctica). So perhaps the sum begins to look a little more balanced between north and south "pointing"..

I think the problem is that once the eye scans an essentially random distribution with one idea in mind, perhaps encouraged by the tapering of the southerly continents, the viewer begins to see that idea expressed everywhere. The human eye tends to be pattern-finding.

Secondly, cartographic conventions introduce a bias. Think of the great North-facing coasts of the globe, mainly of Russia, Siberia, Canada, and of course the entire coast of Antarctica, (all of which by definition faces north!). These are where you would naturally expect to see northern-pointing peninsulas. Being close to the poles, these coastlines are so compressed in 2-D map projections that they hit the eye far less forcibly than they should.

Other examples you cite are, I think, dubious. Can Iberia really be said to “point”? Might not Europe be regarded merely as a westerly-pointing peninsula from the Eurasian continent, much as Alaska is in relation to North America?

I am sure this isn’t the whole story. Nothing in geology ever is! But I hope I have given you a few pointers.