The Lightning Stones are a line of 20-foot tall pointed menhirs in the southern reaches of the Barrier Walls mountains, near the border with Nex. Lightning strikes these menhirs with unnatural regularity, causing otherwise invisible runes and glyphs within the stones to briefly glow after every strike. Garundi legend says this is where earth and air elementals square off in combat. Dwarven legend says the stones funnel lightning deep into the earth for aberrant purposes.
Sources: Pathfinder Chronicles Campaign Setting