When the catastrofe of 79 a.D. occured, Herculaneum was submerged under a torrent of mud and lava that hardened into a soft tufa (a kind of course rock) that preserved many of the timber features and houshold objects which can be seen today.
A large portion of the old Herculaneum is still buried under the modern town and even today excavation are going on to discover what treasures lie buried under the rock, to the extenextent that some families are being rehoused so work can continue.
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