Bitumen-stabilized earthen architecture
A new article by a member of the Chair is available on ScienceDirect.
The presence of fossil hydrocarbons in archaeological construction samples from a Mexican Gulf coast site, dated 100BC-AD600, led to the hypothesis that petroleum derivatives were used to stabilize earthen construction, a knowledge thought to originate in the early XX century. A two-step study first compared 10 construction and 6 paleosoil samples with previously profiled archaeological bitumen of the site of La Joya. This procedure required to adapt the standard bitumen protocol by Gas Chromatography coupled to Mass Spectrometry and δC Isotope Ratio Mass Spectrometry for low concentration of organic extract in earthen sediment samples, and allowed to infer that bitumen was added to the construction samples. A second step compared the La Joya results with 63 earthen architecture samples from 13 sites in Mesoamerica to evaluate whether the strategy was unique to the site or if it was shared and possibly exported. The results indicate that the use of bitumen as a stabilizer was opportunistic in sites on the Gulf coast located nearby surface seeps, but that the technology was not exported to sites in contact with the Gulf region.