by Elio — Cer­tain large un­der­ground cav­erns owe their majesty to the bio­chem­i­cal ac­tion of tiny bac­te­ria. In many parts of the world, cav­erns are formed by the dis­so­lu­tion of cal­cium car­bon­ate de­posits by sul­fu­ric acid (this is known in the trade as "sul­fu­ric acid speleo­ge­n­e­sis"). Such mi­cro­bial min­ing formed the...