In AD 79 an eruption of Mount Vesuvius effectively wiped out the Roman town of Pompeii. Volcanic ash and pumice rained down on the town for about 18 hours (to depths of 8-10 feet); many roofs collapsed under the weight. This was followed by a nuée ardente, explosive superheated pyroclastic clouds of toxic gas and debris that came in six surges. Two bodies exhibited in the Stabian Thermal Baths Pompeii was completely covered and remained hidden for over 1600 years.
In 1748, Pompeii was rediscovered--not only its houses, but (eventually) some of its citizens. Although only fragmentary skeletal remains were found there, hollow spaces within the hardened volcanic debris revealed the forms of many deceased Romans. Suffocated by volcanic gasses and covered in ash and debris, their bodies eventually decayed inside the hardening matter. This air space essentially formed a mold, since the ash that had surrounded the person retained an imprint of the body. Excavators realized this and filled the air pockets with plaster. The resulting "plaster mummies" poignantly capture the human tragedy of Pompeii.