Inspired by the nightjar walk, we decided to explore the Tamar trails created by TV AONB. We started at Bedford saw mills and walked down to the Tamar and then up and down the trail that follows the river. The first photo shows a giant hogweed. It is described as an aggressive and nuisance invader and it is irritant to the skin, but nevertheless it is very impressive. The sheep are grazing in meadows of Blanchdown farm Unfortunately this means you cannot walk along the river bank at this point.
The water in the stream below has stained the rocks a vivid green I suspect this must be due to minerals washing out of mine workings higher up the valley. The foliage also looks an unnaturally bright green and that always makes me suspect that there are high concentrations of metals in the soil. (Is this the explanation, see
link )?
4 comments:
I think the colour in the stream is probably due to copper. It reminds me very much of something similar I've seen at the Gawton mines further down river. I first came across it in the early '70s and there was an old chap living in a caravan nearby who was making a living from the high purity copper he was able to scrape off scrap iron he left in the stream for a few days. If memory serves me correctly, the process was 'electrolytic deposition'. I seem to remember that a very young Sue Lawley interviewed the old chap for the BBC at the time. And the effect the copper has on the plant colours is called 'copper chlorosis' (but I'm open to correction on this).
I thought chlorosis was a slight yellowing of leaves seen in poor soils and iron deficiency. One striking feature of plants growing on spoil tips is the unnatural shades of green they show.The only references on Google to cu chlorosis are very technical!
on further research could it be the paris green of copperacetoarsenic?
http://en.wikipedia.org/wiki/Paris_Green
Sounds like some further research is required and another visit to Gawton.
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