headcanon: what makes a place particularly supernaturally active is not leylines but mana, which is to the spiritual as humus and petrochemicals are to the physical: a residue of old dead life. Conscious life can both use and replenish mana at greater volumes. Like petrochemicals and soil mana can be exhausted when use exceeds replenishment; this is how cultures decline and achieve palingenesis through war and genocide