Influence of the deterioration type and age on the deterioration degree of 191 ancient limestone steles in the Guihai Forest of Steles, southern China

The relationship between the deterioration type (DT) of ancient limestone steles and deterioration degree (DD) and the relationship between the carved age and DD were investigated and studied. Data on the DT, DD and carved age were collected and analysed from 191 ancient limestone steles in the Guihai Forest of Steles, Guangxi Zhuang Autonomous Region, southern China. A distribution map of deterioration on each stele was drawn, and six DTs were identified, including biological colonization, missing parts, exfoliation, erosion, encrustation and graffiti. The DDs were visually assessed on a generalized 4-point scale: intact, slight, serious and extremely serious. The carved ages of steles, which ranged from 894 to 1940 A.D., were verified. The relationship between the DT and DD was analysed using partial correlation analytical methods. The correspondence between the carved age of the limestone stele and the DD was established and analysed. The results show that (1) the DD was strongly correlated with erosion, which was mainly caused by seepage water and rainwater, and the DD was weakly or not correlated with the other five DTs; (2) the DD was related to the carved age, but the relationships were weak. The results provide a scientific reference for the conservation and restoration of these caves.