Agricultural terraces in the UK, new insights from biogenic microremains.

Agricultural terraces are anthropological features that shape the landscape. In Europe, their construction and use dates back to the late Neolithic and today they can be documented across the continent corresponding to different chronological periods. In addition to the impact on the landscape and the environment, the possibility of expanding the production area, through the construction of terraces, makes it possible to improve the quality and diversity of the crops produced, thus contributing to increasing demographic and social complexity. To better understand the role of agricultural terraces in the environment and society, the TerrACE project has developed a high-resolution research protocol to be applied to different agricultural terrace systems in Europe without chronological distinction. This multi-proxy research includes, among others, the analysis of biogenic microremains to identify past cultivars.

We focus here on the use of biogenic microremains (phytoliths, diatoms, ash pseudomorphs, and faecal spherulites) and FTIR analysis applied to four agricultural terraces from the United Kingdom, with different chronologies: on the one hand, the prehistoric terraces of Plantation Camp and the medieval terraces of Gueswick both in northern England, 72 km apart; and on the other hand, the prehistoric terraces of Charlton Forest and Blick Mead both in southern England, 78 km apart. In addition to evaluating exploited cultivars, we also seek to identify differences and similarities between these sites. While ash pseudomorphs and fecal spherulites were not documented at any of the sites, phytoliths were well preserved at Plantation Camp, Gueswick, and Charlton Forest. In general, it can be observed that the amount of phytoliths decreases with depth. Along with the phytoliths, diatoms have been identified, although to a lesser extent. The most abundant phytoliths were those produced by grasses, especially those of the C₃ Pooideae subfamily. Even though evidence of crops is scarce, analyzing the short silica short cells phytoliths we were able to identify barley in Plantation camp, which agrees with its location and chronology. These same analytics, along with complementary methods (i.e., DNA), are being conducted in the other sites to obtain more information regarding the plants cultivated in the terraces.