Formation processes at the Ohalo II submerged prehistoric campsite, Israel, inferred from soil micromorphology and magnetic susceptibility studies

Abstract

Soil-geomorphic analysis coupled with micromorphology, SEM/EDS, magnetic susceptibility, and conventional sedimentological studies allowed us to reconstruct the site formation history and validate the archaeologically observed variability of human activities in the prehistoric camp of Ohalo II (19.5 ka B.P.), Sea of Galilee, Israel. The cultural layers rest upon the Late Pleistocene Lake Lisan deposits that accumulated under conditions of changing water supply and increasing rate of sedimentation from deep-water varvelike deposits to basaltderived, near-shore sandy lacustrine deposits. Intermittent occupation is recorded in some localities, indicating short-term inundation episodes, which led to partial truncation and deformation of the sediments, primarily in the eastern lakeward part of the site. On the elevated, landward positions, incipient soils with strongly bioturbated profiles formed. Micromorphology demonstrates that intentional flooring was applied within the remains of brush huts, where millimeter-sized, horizontally organized burnt and unheated vegetal tissues were likely to have been placed upon the compacted ground. In fireplaces, the cultural deposits in thin sections are composed of strongly mixed, abundant wood charcoal, ashes, and fishbone remains. Post-depositional alterations were controlled by intermittent inundation of the site and salinization, which induced gypsum and pyrite deposition, primarily along decayed roots, and eventual pyrite oxidation. Accumulation of sodium and chlorine in the post-occupation deposits is likely to have occurred because of discharge of saline groundwater. Although only suggestive at this stage of research, the conclusions drawn from magnetic susceptibility parameters of archaeologically related deposits at Ohalo II fit well with the micromorphological reconstructions and provide new information on the Late Pleistocene evolution of the Lake Lisan/Sea of Galilee fluctuating system. ᭧

Stone Age hut in Israel yields world's oldest evidence of bedding

“…The latter were set erect, as some kind of foundation or symbolic elements, before the time when the floors were used for accommodation purposes. Altogether, each of the field observations and research results (e.g., distribution patterns and flint refitting) provides independent support for our claim of in situ preservation on the Ohalo II hut floors (30)(31)(32).…”

“…The last inundation was of a greater magnitude. Calm relatively deep water covered the site, and the immediate deposition of fine clay and silt layers began (29,30). Together, the water and sediments sealed the site and protected the remains in situ for millennia.…”

“…Here, floors were classified as dark anthropogenic layers that were oval-shaped and measured several centimeters thick, could be distinguished macroscopically and microscopically from surrounding layers and deposits by color and matrix and were rich in charcoal, bones, flints, and other everyday debris (30,31). The floors of six oval brush huts were identified.…”

“…Furthermore, thin sections of the hut 1 floors and the inbetween layers, which were analyzed under an optical polarized light microscope, verify the presence of in situ floors (30,33). The bottom floor, on which the bedding remains were preserved, is a complex depositional unit composed of pedogenetically reworked, bioturbated calcareous clay containing 10% silt, occasional rounded basaltic clasts, and abundant charcoal fragments.…”

Environmental magnetism: Application to cave sediments

“…Verosub et al, 1993), marine deposits (e.g. Yang et al, 2008;Aidona and Liritzis, 2012) and archaeological sediments (Aidona et al, 2001;Tsatskin and Nadel 2003), based on mineral magnetic properties.…”