wildwomanswimming

One woman's wild swimming adventures in the west country

Bank Holiday Dipping

The First Pool

The First Pool

Honey and I went to Dartmeet this afternoon, and only just squeezed TrannyVan into the packed car park. We wandered downstream, but I could have counted the people we met on my fingers and toes. Our first dip was in the big pool only a few hundred meters from the bridge and there was neither sight nor sound of anyone. The water was golden and glassy, with every rock and fish and granule of sand clearly visible through the rippled reflected sun. The water today is noticeably chillier than of late and I felt a slight but definite skin burn. We dried off on the bank in the light breeze and warmish sun before trundling down to a faster stretch for a race up against the current. Squadrons of dragonflies droned around the bank.

The Second, Friskier Pool

The Second, Friskier Pool

 

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6 thoughts on “Bank Holiday Dipping

  1. Still Pool at Staverton was very, very busy with swimmers on Saturday afternoon 😉 and a few again yesterday but I had a wonderful swim this afternoon and I thought the water was warmer today than Sat. though it is getting chillier slowly and inevitably. Grab every moment in a month it will be game over for the summer

    • We were there on Sunday, just posted the blog! You’re right about grabbing swims, it was almost autumnal today

      • I think you’ll find it was Saturday, about 3:30, I was the one sat on the bank talking with Sophie.

        You missed the gnome garden, it’ll still be there next time.

        The green pebbles are pale grey limestone covered with algae. Alternatively you’ll find bits of concrete covered in the same bright green algae. What both have in common is the lime part of the equation. Other pebbles are granite and sandstone and mudstone and etc including house bricks but they have a brown algae covering if anything at all. After that I have a number of theories but I’m still working on it.

  2. Thanks Chris, I wondered whether the type of stone was relevant. So that was you! Sophie said she was supposed to text you and forgot…
    Yes, Saturday it was, I never have much idea what day it is!
    Hope to meet you on a swim soon.

    • Yes that was me, not much I know, but it’s all I’ve got.

      As far as the stones go; is it the type of stone that makes the algae so green whereas when the same algae grows elsewhere it is deficient in some nutrient and therefore only brown? I don’t like that hypothesis, there are green’, ‘brown’ and ‘red’ algae depending on the pigments so I guess we’re looking at a different kind of algae. So, does that type of stone favour the green algae but discourage the brown? And if so, why? Green algae grow faster than brown so maybe the green is able to colonise the surface of the limestone pebbles, which must be dissolving in the acidic water, fast enough to get a ‘foothold’. Maybe the green are tolerant to the alkali composition of the limestone whereas the brown are not. Limestone is calcium carbonate but around here it grades into ‘dolomitic’ limestone which is rich in magnesium. Magnesium is to the green chlorophyll pigment what iron is to haemoglobin in our blood, so maybe as the limestone dissolves the green algae are able to pick up extra magnesium, make extra chlorophyll and so turn very bright green and are able to grow faster. I think the algae must be getting something specific from the limestone otherwise they would be growing on every pebble turning the whole place green. Whatever the explanation it is a very specific relationship.

  3. Interesting, especially about the magnesium. As a gardener on Dartmoor, with a very acidic soil, I know that only certain plants will grow here. I guess algae must have a similar propensity, in this case the green likes the lime, and its colour is enhanced by the magnesium. Maybe the porosity of the limestone helps too?

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