Seychelles’ Rocks

Of all 155 islands belonging to the Seychelles archipelago, only 40 are solid rock; the remainder are coral reef atolls.  This solid rock is invariably granite, (technically speaking granitoids – geologist speak for granite-ish) which makes these islands special: they are the only granitic islands in the world.

NB – the following paragraph contains sweeping statements with zero references to back up my assumptions: (How very unscientific of me)

Most small islands around the world are usually volcanic in origin; they often, conveniently, have a volcano, whether active or dormant, dominating the skyline to tell us so.  Granites are something one would assume to be in the middle of a continent, surrounded by other rock types that it has intruded into.  The Seychelles doesn’t have a single sandstone outcrop, or a shale ridge, or a volcano for that matter.

It really does beg the question of “how the &£(% heck did they get there?”  Apparently this question has been bugging a few academics out there too – but couched somewhat differently.

They also happen to be the oldest islands in any ocean, dated to be 750 million years old.  That means that they were emplaced (i.e. they intruded into other, surrounding host rocks of one sort or another) during the Precambrian age.  It wasn’t until much later, during the mid-Jurassic (~167 million years ago) that the Gondwana Supercontinent began to break apart.  The Seychelles, attached to East Gondwana (the continental Grand-daddy of Antarctica, India, Madagascar and Australia) split from its African continental counterpart.  Not content with getting Out of Africa, the East Gondwana continent showed signs of stress and further fragmented. (Sounds a bit like South African political parties to me).

India, along with Madagascar and Seychelles were on the move – heading northwards from about 115-120 million years ago.  However, Madagascar appeared to get left behind from 84-95 million years ago.  By 65 million years ago, India also “dropped” the Seychelles and continued to race forth, slamming into the Eurasian plate.  Clearly, the Indian plate doesn’t know how to apply the brakes – it’s still on the move!

So the Seychelles micro-continent was abandoned to the ocean that surrounds it – to be pillaged and plundered by traders, sailors and pirates alike.

Still, it is rather beautiful despite those hectic beginnings…

The granites have a very peculiar weathering pattern, well peculiar for a granite: gullies are eroded by rain water leaving sharp ridges – a bit like what you would normally expect of soil erosion patterns.  I guess that’s what happens in the Tropics.  Lots of rain…

The island below (also seen in the first photograph, above) is St. Pierre.  It is allegedly the most photographed island in the Seychelles featuring in many adverts and tourist brochures, alike.  Apparently, it is because it epitomises the ideal of “Tropical Island Paradise”.  I didn’t hesitate to get a shot of it, myself…

Sources used in making this post: (Wikipedia is so useful, isn’t it?)

Wikipedia: Geography of Seychelles

Wikipedia: Seychelles Plate


13 thoughts on “Seychelles’ Rocks

    1. Hi aixecantelpolze – I think you might very well be right about that! – Hope you get there to confirm your theory 🙂
      Thanks for visiting and leaving a comment!

  1. Lu, there is an island in Indonesia called Belitung (you can google the image of it) which has granite boulders. So this means The Seychelles are not the only granitic islands in the world, aren’t they? Please correct me if I’m wrong.

    1. Hi Bama, I’ll look into that – what I think they mean is that it’s the only cluster of granitic islands that are not attached to/close to a main continental land mass.

  2. Beautiful pictures! I didn’t get to go to St Pierre, but I loved Anse Source D’Argent, a lot. *Sigh* Thank you… makes me want to go back

    1. Hi sofitoffee – We had the pleasure of looking out at St Pierre from where we were based.. We didn’t get to land on it though – I’m not sure that anyone is allowed to. We did pass by on a small boat though 🙂
      Thanks for your comment – I also want to go back!

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