Marble from Hierapolis: decay, conservation and monitoring of surfaces and the environment

The archaeological site of Hierapolis is unique in terms of the conservation and decay phenomena of marbles and travertines. Environmental factors (i.e. thermal springs, high thermal stress, and seismic faults) together with the microstructural characteristics of the marble types play a fundamental role in the durability and conservation state of the materials. This paper presents a multi-analytical approach aimed at identifying the phenomena and causes of alteration and decay. The sample analyses were combined with the monitoring of the main environmental parameters and with an analysis of the water and gases present in the site. The untreated and treated marble surfaces were also monitored over a 3-year period.