Bog pools, large and small, dot the peat covered terrain of Mayo, from down in the valleys to the very top of our 700m+ mountains. I love them. They are a regular feature of our walking holidays and are especially evocative when you can see the sea from standing by one.

Bog pools catch the light unlike any other feature of the landscape. Full of peat dust and mosses, they can turn from deep rusty red, through a sort of mossy green, to beautiful rich blue, as the clouds drift by and the sun peaks out.

From as little as 2 m2 up to over 400 m2, bog pools tend to form where water can remain stagnant on the lowland bog or hilltop plateau. Perhaps older bog pools were formed where there was a natural depression in the subsoil as the bog grew. They then grow outward, creating a patterned landscape of pools surrounded by open bog, some of which can be reasonably dry, with other parts, particularly between pools, very wet. The very borders of pools, however, are often among the drier parts.

Interestingly, a Scottish research project from 10 years ago found that, as they grew bigger, bog pools became more elongated and convoluted in shape. The study concluded that, while wind and pool waves play a role in bog pool expansion, ground slope is more important a factor.

Next time you’re on the mountain, out on the open bog, or on one of my walking holidays, stop for a while and admire the lovely bog pools. Mind you, don’t step in them or the sphagnum moss all around !