A geophysical approach to buried site detection using down‐hole susceptibility and soil magnetic techniques

Abstract

Recently developed down-hole magnetic capabilities and laboratory soil magnetic techniques are combinedin ageophysicalapproach toidentify buried archaeologicalsites.Down-hole magnetic susceptibilitymeasurements areused tolocatepalaeosols and soilmagnetic studiesare applied to evaluate whether an associated human occupation is likely.This geophysical approach has the potential to locateandexplore buried archaeologicaldeposits acrossvaried environmentsin a cost-effective, efficient, and relatively non-invasive manner.This approach was developed and tested on sites in Minnesota and North Dakota, USA. Prototype Bartington Instruments MS2H down-hole sensorsallowedidentificationofmajorstratigraphicalunits, buried occupation layers and non-cultural palaeosols at these sites. Buried soils correlated with enhanced susceptibilities.Buriedculturalsoilsproduced, insome cases, asignalover twicethemagnitudeofnon-archaeological palaeosols. Although this magnitude shift suggested a possible avenue for determining if ancient land surfaces had been occupied by humans, laboratory soil magnetic techniques, which allow an understanding of changes in composition, concentration and/or grain size of the magnetic carrier that produce this contrast in magnitude, were found to be much more effective in making this determination. These soilmagnetic testswere applied to sediments collected from the down-hole locations.An increase in magnetic remanence carried in the coarse soil fraction was found to consistently and reliably distinguish those soils associated with human occupation. Investigations into the origin of the magnetic signature have suggested this remanence residesin nodules of burnt clay foundin the archaeological soils. Asit is suspected that domestic firesproduced these clayaggregations, thisphenomenon mayextendtoawiderangeofsitesandthusprovideatechniqueforburiedsiteidentificationthatisbroadly applicable

Environmental magnetism: Application to cave sediments

“…As it is reported by several authors (e.g. Dalan 2006Dalan , 2008 this enhancement is due to an increase in fine grained magnetite or maghemite.…”

Cutbank Geophysics: A New Method for Expanding Magnetic Investigations to the Subsurface Using Magnetic Susceptibility Testing at an Awatixa Hidatsa Village, North Dakota

“…Modest levels of enhancement were also expected given the relatively recent age of this landscape. The magnetic enhancement of surficial off-site soils that was documented as part of this study is commensurate with enhancement levels of 1 to 4 times base levels measured at alluvial sites within the Red River Valley [50] (p. 189). Though only one station at KNRI was studied to obtain the background (off-site) signature, values measured at this station did match sterile soils measured below cultural layers at several on-site stations.…”

“…At the Double Ditch site in North Dakota ( [43,48], also summarized in [2]), a prototype Bartington Instruments MS2H down-hole sensor was tested on a subterranean food storage pit, house basin, borrow pit, mound, and paleosol. Magnetic susceptibility studies had also been shown to be effective in alluvial settings for identifying buried soils, tracing them across the landscape, and mapping concentrations of human activity [50,51]. Research by Kvamme and Wiewel [48] at Double Ditch involving profiles of susceptibility along previously excavated unit walls [43] yielded patterns useful for distinguishing a Figure 18.…”

“…Linford and Canti [64] examined ash and thermally altered soil in experimental fires and observed significant enhancement due to fine-grained magnetic material in short term (1-4 day) campfires. Studies on buried soils from archaeological sites in the Red River Valley [50] suggest enhancement of both SP grains and those at and above the SP-SD boundary deriving from burned soils directly below domestic fires.…”

Geoarchaeological prospection of a medieval manor in the dutch polders using an electromagnetic induction sensor in combination with soil augerings

“…These sensors could provide more information on structures at different depths. The auger point observations could be accompanied by sensor point measurements in a borehole (Dalan, 2006). But direct observation, including soil auger observations or test pits, will remain necessary for a good interpretation of any site.…”