Lecanora gangaleoides :

Learn your lichens 6:

Lecanora gangaleoides

Learn your Lichens
around Settle Series
1. Arthonia radiata
2. Caloplaca flavovirescens
3. Acrocordia conoidea
4. Squamarina cartilaginea
5. Xanthoria parietina
6. Lecanora gangaleoides

Lecanora lichens have apothecia (reproductive bodies) that look like jam tarts: In the case of L.gangaleoides  the  "jam tarts" are 1-3 mm across, the "jam" is black, and the thick rims are very pale grey, almost white.

It is growing on a stone in the wall next to the post/tube that may be used for measuring water depth for the Environment Agency at Penny Bridge, Settle

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This looks like a very similar lichen called Tephromela atra but in L.gangaleoides, if the surface of the thallus is picked away or damaged you can see the orange medulla underneath, as in this picture below:

Quoting from Lastdragon.org:

Thallus generally light grey, warted-areolate, with orange colour in the lower medulla exposed if the surface tissues are picked away (visible at the left of the photograph); apothecia with thick, thalline margins and black discs. Widespread but more common in the north and west and on the coast, on base-poor rocks and stonework.