Calcrete formation and implications for buried archaeological deposits in the Mariana Islands, western Pacific

Calcrete zones of cemented sands are found repeatedly at beach sites in the Mariana Islands, western Pacific region, with mid- to late-Holocene artifacts and midden sealed within and beneath these layers. Three site-specific cases demonstrate that the cementation process of the calcareous sand material post-dated the deposition of artifacts and midden. Archaeological efforts must be prepared for deep excavation through zones of cemented sand. Also, recovery of preserved ancient materials can proceed by excavating large hardened blocks and soaking in light (5%) acid. This knowledge about formation process and recovery technique may prove useful not only in the Mariana Islands but also more broadly in other regions with similar settings.