Buried sand grains are dating Kallirhoe, Herod's palace and port on the Dead Sea

The American Center of Research (ACOR) in Amman is building a timeline for 'Ain az-Zara, on the Dead Sea's eastern shore in Jordan, by optically stimulated luminescence (OSL) dating of its sediments, the centre said on 15 October 2026. In Roman times the place was Kallirhoe, the port of the fortress of Machaerus (Mukawir) on a nearby mountain.

Quartz and feldspar grains in sand absorb energy from natural radioactivity while buried. Exposure to light, from wind, water or a shovel, resets that store to zero, so measuring it gives the time since a layer was last in daylight; finds lying in the layer can probably be dated by their position in it. The samples now in the laboratory were taken in 2023, and more will be collected in the season beginning this month. ACOR's photograph of the analysis shows Prof. Sahar Al Khasawneh of Yarmouk University. The principle is the one behind thermoluminescence dating of pottery, where firing in the kiln resets the count.

The work is funded by a two-year award from the US State Department's Ambassadors Fund for Cultural Preservation, which ACOR announced in March 2026, to excavate a Hellenistic and Roman port and seaside palace there with Jordan's Department of Antiquities and open them to visitors. The grant's project title calls the palace Herod's. In 12 BCE, during the Roman period in Cyprus, Augustus gave Herod the Great half the revenue of the Cypriot copper mines and the management of the other half.