Possible tsunami inundation identified amongst 4–5th century BCE archaeological deposits at Tel Ashkelon, Israel

The eroding coastal sections of Ashkelon, Israel contain exposed sequences of natural and anthropogenic sedimentological deposits; some of unknown origin. Ashkelon, an important and long-occupied ancient coastal city, is directly referred to within written records of past tsunami events yet field studies and archaeological descriptions have not yet corroborated these claims. This is not unusual, nor unexpected, given the amount of anthropogenic and natural disturbance that can erase the sedimentary remains, as well as the relatively recent advancements in identifying such deposits. A sequence of sediments at the base of an eroding coastal archaeological section shows clear waterborne transport characteristics and was previously interpreted as alluvial; however, no alluvial sources could be associated to the deposit. In this study, the sedimentological characteristics of this section were described and analyzed in greater detail to determine their nearest similarity to possible transport mechanism such as storms, rivers, and tsunamis. The deposits contain fining-upward sequences, rip-up clasts, imbricated inclusions, fine mud layers, microfauna (foraminifera), and broken diagnostic pottery from the 4–5th c. BC Reconstructions of the coastline at the time of the event place the sampled profile at least 100 m inland from the shoreline, at an elevation + 2.0 to 2.4 m above sea level. River-channel features were not identified in the section. For this area, modern observations of major storms show inundations of < 75 m which are not coupled with depositional deposits (erosional only), suggesting that these deposits are not storm-related. Rather, it is possible that the deposits support the arrival of an undocumented tsunami at Ashkelon some time following the 4–5th century BCE. These results reinforce the importance of the reassessment of many coastal sedimentological studies in light of improved capabilities of recognizing possible tsunamigenic sediments, as well as increased field efforts for the purpose of producing more complete tsunami catalogues; and also highlights the need to better record and document eroding coastlines that may contain valuable information regarding both anthropogenic and natural history.