Magnetic detection of ship ballast deposits and anchorage sites in King Herod's Roman harbour, Caesarea Maritima, Israel

An assessment of lithostratigraphy for anthropogenic deposits

“…Although evidence exists for submarine deposition (e.g. through the disposal of ship ballast: Boyce et al 2009), anthropogenic sediments are most commonly deposited in terrestrial, subaerial environments. Anthropogenic sediments may overlie earlier natural or anthropogenic deposits.…”

“…A range of techniques including resistivity imaging, ground penetrating radar (GPR) and gravity surveys are used in archaeological, engineering and environmental studies to delimit and characterize anthropogenic deposits (Fenning & Williams 1997;Guerin et al 2004;Kulessa et al 2006;Boyce et al 2009;Boudreault et al 2010). GPR, in particular, is used extensively by archaeologists to characterize anthropogenic deposits on a site scale (Bladon et al 2011).…”

Deterioration of Israel's Caesarea Maritima's ancient harbor linked to repeated tsunami events identified in geophysical mapping of offshore stratigraphy

“…Caesarea harbor phases, from initial construction to the present, have been reconstructed using sedimentological, geophysical (i.e., magnetometry), and archeological surveys (Reinhardt et al, 1994;Raban, 1999, 2008;Boyce et al, 2009). The most recent summary (Reinhardt and Raban, 2008) suggests six such phases, summarized as follows: 1) initial construction, 1st century CE, 2) 1-2nd century CE destruction, 3) 3-4th century CE, unprotected (meaning exposed to the open sea and therefore without intact harbor features), 4) 4-6th century CE, natural/unimproved harbor, 5) 6th century CE, sand infilling, and 6) 6-11th century CE, renovation/destruction.…”

Remote sensing for underwater archaeology: case stud-ies from Greece and Eastern Mediterranean

“…The magnetometer survey showed the existence of buried cargo which was extended from the visible wreck. Boyce et al, 2009 carried out a marine magnetometric survey at the ruined remains of the Roman harbour of Caesarea Maritima which are located on the northwest coast of Israel. The large variations in magnetic intensity across the Roman harbour result from the presence of magnetite-rich hydraulic concrete (pozzolana) within the buried harbour foundation.…”

“…The large variations in magnetic intensity across the Roman harbour result from the presence of magnetite-rich hydraulic concrete (pozzolana) within the buried harbour foundation. Furthermore, ballast stone deposits consisting of foreign igneous and metamorphic boulders were detected due to the strong magnetic contrast between the ballast deposits and the natural seabed sediments (Boyce et al, 2009). …”