Mapping the Shoreline 2: Stromatolites

The river holds a lot of history.

Some of it has flowed downstream with the currents and moved on to the sea but some of its oldest history is still here. And when the water is low you can find one of the most striking features visible along the Ottawa River shoreline: The stromatolites on the Quebec side of the river. They have been scraped down by glaciers and eroded by time but the ancient stromatolite bed remnants are still remarkably beautiful and visible.

The seaweed growth on the rock above shows that the stromatolite formations are often covered by water.


These stromatolites are over 450 million years old and were formed during the Paleozoic period when this area was located near the equator and was covered in a warm shallow sea. The stromatolites are built up in layers by cyanobacteria, also known as blue-green algae, and are accretionary structures rather than body fossils.



This cross-section above, of a dislodged and abraded stromatolite shows the many thin biofilm layers that are built up by cyanobacteria (blue-green algae).

Nearby fossil-rich rocks – which are slowly being eroded by the current – exposing various fossil snails.




The Champlain Bridge linking Ontario and Quebec; a striking contrast between the modern and the ancient world.

Related links and references:

Mapping the Shoreline 1
Ottawa River Keeper
Wikipedia:Pangaea
Wikipedia:Stromatolites

All images © Karen McRae, 2012

60 thoughts on “Mapping the Shoreline 2: Stromatolites

  1. What an interesting post Karen.. I had never heard of stromatolites before and definitely have never see such a thing.. I had imagined they should be lovely colours but I guess not as I’m sure you woulddn’t use B&W if they were 🙂

  2. Fascinating, just fascinating.
    When the time scale was gone beyond of our imagination
    it goes into philosophical or spiritual level, of which
    your photography is specialized.

  3. Really unusual. Funny, it seems like rocks should be so serious, but those ones with seaweed look like walruses with whiskers or somesuch and make me smile. They look oddly old and wise. I am now quietly suspecting I may have just eaten too many sweet things at lunch 🙂

  4. You really capture the essence of place with your photos. The world’s oldest life form, extraordinary antiquity. Amazing too that the stromatolites in Western Australia are not only preserved but still growing.

  5. I’m particularly taken by the lines, patterns, textures and shapes, quite apart from their uniqueness. My preference is for the b&w – they emphasize and focus attention on these characteristics.

  6. How fascinating, thanks for sharing this..I love to know that this humming history is there..very grounding somehow, we are all part of where we came..

  7. These are really beautiful. My sister works on fossils formed from cyanobacteria, so I have been learning all about them! Its amazing what beautiful shapes the goo like microbes can form when preserved in rocks.

    1. Hi Anne, that is very cool that your sister studies fossils formed from cyanobacteria! How interesting. Is she working in England?

      I see you are/were in Vancouver, I’ll have to pop over to your blog.
      Cheers!

  8. A la Lisière de l’Ancien Monde , Ce Fleuve Traverse les Frontières ,
    Ainsi la Roche mise en Lumière , Ouvre à la Vue une Vie Profonde ,
    Celle où les Âges Veinaient la Ronde , sous d’Autres Formes en la Matière ,
    Tant de Poésie en l’Univers , s’écoule au Cours du Fil de l’Onde.
    ~
    NéO~
    ~
    Merci pour cette Belle Découverte 😉

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