I would like to send in my Lichen results to the British Lichen Society for the first ten monads of my hectad SD86 (from Rathmell to here- Helwith Bridge) but somehow I did not write up my results for this monad to locations to a precision better than SD8069.
So this is a good excuse to resurvey parts of SD8069 the Helwith Bridge aquare.
So I set off on the evening of the 2nd May 2025.
The geology here is well studied and very interesting - with folded 450 MYR old siliceous rocks at the bottom (Silurian and Ordovician) and an unconformity with a 100 MYR gap and then Carboniferous Limestone on top (actually the limestone is just into the next monad and hectad to the west).
The rocks at the bottom have been quarried for many years at Helwith Bridge Quarry
The names of these rocks seem to change EVEN FASTER than Lichen names. I would, at O level 50 years ago, have called these "Silurian slates" - I like the alliteration. Then I was told they were "Greywackes" which is sandstone formed when sandy deltas slipped down into the sea and the pressure metamorphosed the sandstone. Then last week I was told it was part metamorphosed siltstone. The British Geol Survey this week calls it "Horton Formation - Siltstone. Sedimentary bedrock formed between 427.4 and 425.6 million years ago during the Silurian period.".. And Says the old name "Horton Flags" is now obsolete. And the rock next to it is Austwick Formation Sandstone (Silurian Period) Map
Anyway it is siliceous rock.
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| I took this to be Porpidia macrocarpa |
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| View from site towards Penyghent |
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| Some sort of Cladonia. there was a lot of C subcervicornis around. |
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| Normandina pulchella on moss (Hypnum maybe cupressiforme) on sloping rock outcrop at ground level |
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| Ptilidium ciliare and Peltigera membranceaea |
See other lichens posts
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