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, recov- ery of preserved ancient materials can proceed by excavating large hardened blocks and soak- ing 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 sim- ilar settings.