Thank you for the links.
The first one could be construed as non-natural, but the second one is definitely natural.
Even if the second one is man-made it does not signify any great leap from the creators of stonehenge i.e. neolithic hunter-gatherers.
This isn’t even the pyramid level (Chalcolithic) - that’s not to dismiss stonehenge as nothing, they are impressive, but they aren’t “civilizations” as in the sense of “civis” i.e. cities.