Calling all geologists.

Homeward bound. Not much of any note. Got an old wrinkly with a confederate cap on, A lad who carried his camp in a pair of cycle paniers, a couple camping from a tiny little trailer towed by a motor bike, a "Shetlabella" pony which seemed a wee bit big to be one of them and too small to be t'other: so we rechristened it.
We stopped in at a builders' merchants in Hawes, still trying to find the illusive "C" clip, (Scarce as rocking horse manure, hens' teeth and more things of that ilk) where I spotted a display of paving stones: of which this bit of what appeared to be sandstone was one.
Suggestions (legal & anatomically feasible) in a plain brown envelope please.