Alkapton said:
How would one dig an artificial cave?
Could a boulder choke ever be described as artificail, even if it is in an artificial cave?
It depends what you mean by "artificial cave" - the term seems to have been used in more than one way in this thread.
You can manufacture something out of bits of concrete pipe, hardboard and polyfilla to create something for people to crawl through - for the uninitiated to find out what a crawl feels like, or for the real hard (and thin) men to see how small a gap they can squeeze through...
You can blast out a long tunnel into a hillside to drain water from a mine or under a town to carry away the effluent...
You can honeycomb a hillside with tunnels while mining for sand or chalk...
You can create an underground passageway by tunnelling, cut-and-cover, or by building against a cliff face, to create an imitation cave like the one in the theme park in Shenzhen or Pavey's Cave/Aquarium Cave/Waterfall Cave/Whatever in Cheddar Gorge...
And if you want an artificial boulder choke in your artificial cave, I don't see why you shouldn't have one. You could artistically arrange a suitable pile of limestone boulders or chunks of expanded polystyrene to suit your purpose...
I heard somewhere that most of the caves on Mendip are artificial, anyway...