I have hear rumors of extensive calcite banks in southern Australia, where folks have chiseled out living space underground. I've often wondered how safe they are in case of a flood, as its seems they have gone vertically down, as opposed to the city of Petra in Jordan, where entrances are carved leading horizontally into a vertical cliff (or perhaps more than one cliff face?).

Anyhow, I am also enchanted by all aspects of nature, in which we also have our niche.