Potential of cone penetrating testing for mapping deeply buried palaeolandscapes in the context of archaeological surveys in polder areas

Abstract

Geoarchaeological mapping of wetlands conventionally involves extensive coring. Especially in wetlands marked by a deep palaeosurface (>3 m deep) this can be very difficult and time-consuming. In this paper we therefore present an alternative approach based on Cone Penetration Testing (CPT) for structured, rapid and cost-effective evaluation of buried palaeolandscapes. Both estuarine and river floodplain environments were investigated, including the watereland transition zone (marsh). The efficiency, reliability and repeatability of the CPT method was tested through the comparison with ground-truth core data. The CPT data generally allowed highly accurate mapping of the palaeotopography of the prehistoric surfaces and the overlying peat sequences. Thin organic-rich clay intercalations within the peat layers could often still be identified. Additional pore pressure, conductivity and seismic velocity data (from CPTU, CPT-C and S-CPT) did not add much crucial information and their main use seems to lie in the added value for near surface geophysical measurements. The results of this research clearly illustrate the importance of CPT information for mapping of palaeolandscapes in archaeology

Tracing tsunami signatures of the ad 551 and ad 1303 tsunamis at the Gulf of Kyparissia (Peloponnese, Greece) using direct push in situ sensing techniques combined with geophysical studies

“…The CPT‐based classification of peat usually reveals low q t values for amorphous peat and higher q t values for peat with abundant fibres (Landva et al ., ; Long & Boyland, ). However, fibrous peat, as found in this study, is often falsely grouped into the SBT category ‘mixed silt with clay’ (Missiaen et al ., ). Nevertheless, unit IV peat is clearly depicted in the CPT log by the highest Fr values reaching up to 14% (Missiaen et al ., ).…”

“…However, fibrous peat, as found in this study, is often falsely grouped into the SBT category ‘mixed silt with clay’ (Missiaen et al ., ). Nevertheless, unit IV peat is clearly depicted in the CPT log by the highest Fr values reaching up to 14% (Missiaen et al ., ). Further, HPT data helped to detect unit IV by a noticeable increase of P inj and EC within the peat section.…”

“…However, facies with similar grain‐size distributions overlap on the Robertson () classification chart resulting in both tsunami sands and basal unit I sands showing the same SBT. To overcome this problem, the relative position on the SBT chart must be considered to discriminate between different facies (Amorosi & Milli, ; Styllas, ; Missiaen et al ., ). Unit I deposits of the presented study show F r values varying from 0·30 to 2·3% and q t values varying from up to 8 to 14 MPa for tsunami‐related sands and the basal unit I, respectively.…”

Archaeological prospection of the nearshore and intertidal area using ultra‐high resolution marine acoustic techniques: Results from a test study on the Belgian coast at Ostend‐Raversijde

“…Both are related to soil type and moisture content, and the ratio of sleeve friction and cone resistance (friction ratio Rf) can be used to classify the soil (Lunne, Robertson, & Powell, ). In general, CPT logs allow good distinction between sand, clay, and peat deposits (Missiaen, Verhegge, Heirman, & Crombé, ).…”

Exploring Integrated Geophysics and Geotechnics as a Paleolandscape Reconstruction Tool: Archaeological Prospection of (Prehistoric) Sites Buried Deeply below the Scheldt Polders (NW Belgium)

“…Location of the electromagnetic induction (EMI) survey area and electrical resistance imaging (ERI) and Land Seismics transect on top of the Pleistocene surface elevation model based on geological and archaeological corings (Klinck et al, ; Verhegge et al, ) and cone penetration tests (CPTs) (Missiaen et al, ) (modern tidal ditches were created recently). Top inset map: location of the Scheldt polders in Belgium; Middle inset map: location of Doelpolder Noord in the Scheldt polders (i.e.…”