Luminescence dating of brick constructions being part of Songkhla City Wall, Southern Thailand

摘要

The Fine Arts Department of Thailand excavated parts of the city walls in the western part of Songkhla city, Southern Thailand. This excavation found additional brick walls covering the top and sides of a rock wall, which according to historical records was built between AD 1836 and 1842. In this paper, we use optically stimulated luminescence (OSL) to date the brick attachments in order to understand the construction history of Songkhla City Wall. In total, eight brick samples were collected from the top (five samples) and the side (three samples) of the rock wall. All but one sample have excellent OSL properties and the exception is explained by limited burning of this particular brick during the production process, as also indicated by material properties. The major challenge of this study was the correct reconstruction of the dose rate due to the complex situation onside and the limited documentation. Despite these limitations, our results imply that the rock wall and the bricks attached to its side are contemporaneous. The bricks on top of the rock wall date to AD 1853-1865, a time shortly before a royal visit (King Rama V) to Songkhla in AD 1870. Two samples dating to the latest nineteenth century may imply a later restoration phase.