Wednesday, 27 February 2019

Lichens at Black Hill Capon Hall - and then Victoria Cave

Malham Tarn has lots of floating microscopic algae in it at the moment.

I accompany Allan and Linden Pentecost in their visit to the outflow of Malham Tarn, for Allan to collect water samples to monitor the algae. We then plan to set off to look for lichens and big rocks. We plan to go to for a walk to Victoria Cave.  February 25th  is a record breaking hot day in UK (though the record may get broken on 26th and 27th).

The deeper water next to the sluice looks a bit murky because of the density of tiny algae "dots" in it -  we await a pronouncement on what the algae are. I say "I thought we only had algal blooms in late summer" Apparently not so..

The surrounding area is mostly dry, without streams, because the bedrock is limestone rock which has joints - cracks in it so water goes undergound. However Malham Tarn itself lies on the boulder clay on top of "slate" - (Ordovician greywackes to be precise). which is impermeable to water

Looking at lichens at the fault exposed unconformity near Malham Tarn

A mile to the west of the Tarn these greywackes rocks can be seen at the surface, so we go to see them. This is where the north Craven Fault exposes (sort of)  the unconformity between the slate and the limestone. We are now standing in Langcliffe Parish (outside of the Parish of Malham Moor by less than 100m). We notice daisies in flower. 

J points to some "slate" - greywacke - bedrock. You can see limestone behind.

Linden notices one lichen on the greywacke:  Protoparmelia badia

Then we drive further and walk to Victoria Cave 

Victoria Cave looks splendid in the low angle February sun. The big white lichen on the cliffs is Aspicilia calcarea . Also on the cliffs in one or two places is this tiny delicate golden lichen:
Caloplaca cirrochroa is a beautiful delicate bright orange lichen. The long lobes are just 0.5 mm wide and can have pruinose  tips. If the centre of the thallus has not fallen out, there are bright lemon yellow soralia on it.

More Caloplaca cirrochroa

Caloplaca marmorata (formerly lutea) - the one with orange apothecia

Yet to be identified

Placynthium nigrum with a Toninia verruacarioides growing on it. You can see the blue edge of the Placynthium at the top of the picture

Although we are having a warm week, I only found a few shoots of Blue Moor Grass (Sesleria caerulea) half in flower. In a week the flowers will look really blue.

On the left is Aspicilia calcarea (creamy white and a bit out of focus) and on the right is the very similar looking, but darker grey Caloplaca chalybaea

On the left  and centre is Caloplaca chalybaea -darker grey - and on the right is the very similar looking, but whiter Aspicilia calcarea


View from Victoria Cave across Warrendale Knotts and across the Ribble Valley towards  towards Pendle Hill
Then we return to Settle two miles away and enjoy supper in "The fisherman", Settle

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