A specific ground texture representing a rock type found in the Lochalsh area of the Scottish West Highlands, with a 3d texture provided by an added normal map.
As an application technique, I'd suggest choosing an angle first (since the strata in most locations are parallel to each other, though certainly not always horizontal, dependinng on how they've been left after tectonic collision) then laying down a basic large-scale layer before touching in a few dabs in different smaller scales to disguise the regularity.