Lichen species

Lichen species

Observation - Lichen species - Global. Description: I found this lichen in epping forest, ( and is a forest that the trees loose their leaves) forest growing on an oak tree, in the month of september. I am wondering could any body tell me what species of lichen this is please ?

I found this lichen in epping forest, ( and is a forest that the trees loose their leaves) forest growing on an oak tree, in the month of september. I am wondering could any body tell me what species of lichen this is please ?