Maps on stone

Even if this isn't officially map lichen Rhizocarpon geographicum,  and I think it probably isn't, it looks to me just like a plan of little fields and paddocks with irregular interlocking boundaries, meticulously parcelled out as in the traditional Irish system of inheritance where land was sub-divided equally between a man's sons, generation after generation, leading to ever-tinier and less viable smallholdings.

I could make the predictable joke about "likin' it" but that would unfairly exclude those people who call it "litchen".
 Both pronounciations are acceptable according to the Oxford Advanced Learner's Dictionary.