Lecanora soralifera

Learn your Lichens Series 1. Arthonia radiata 2. Caloplaca flavovirescens 3. Acrocordia conoidea 4. Squamarina cartilaginea 5. Xanthoria parietina 6. Lecanora gangaleoides 7. Physcia tenella 8. Lepraria incana 9. Porpidia tuberculosa 10. Psilolechia lucida 11. Lecanora soralifera  12. Opegrapha gyrocarpa

We will give examples of this,, first in Ingleton Parish churchyard, then in Settle Parish churchyard.

This pale grey - grey-green crustose lichens grows on acid rocks, such as "slate" tombstones, It also grows on the greywacke (a type of metamorphosed sandstone) which form many glacial eratics in our area

The thallus is divided into areoles. The areoles have soralia (minute patches with powdery soredia). - which are a lighter green than the rest of the areole. - See glossaries for definitions of these 
Glossary -  Last Dragon
Glossary - Irish Lichens

The first time I was shown this (thanks AP) on acid tombstone in Ingleton, a big effort was made to see whether the soralia (the minute powdery patches which house the powdery soredia) were at the centre of the aereoles or a the edge. L soralifera has them at the centre.

St Mary's Ingleton

Different year - same tombstone - St Mary's Ingleton

Settle. 

Go to this big block tombstone then look at the upright one just to the left of it

Look at the lichen on the top surface. There is some bluey grey (Porpidia tuberculosa) and some green grey - the Lecanora soralifera