A new multistage construction chronology for the Great Serpent Mound, USA

Radiocarbon Dates Reveal Serpent Mound Is More than Two Thousand Years Old

“…Moreover, because they probably derive from similar near-surface soil contexts, the range of ages from fill and from premound soil horizons buried during construction should also have a similar range of charcoal within it. The 2-sigma distribution of ages of samples collected from near the base of the mound reported by Herrmann et al (2014) ranges between 800 B.C. and 100 B.C.…”

“…Dashed line represents base of mound; location of radiocarbon samples shown on the logs. Letters (A-G) adjacent to logs refer to specific dates in Table 1; A-G from Herrmann et al (2014). (b) Oxcal modeled results of radiocarbon and AMS dating results using error bars and probability density distributions (PDD).…”

“…Horizontal bars show the Oxcal modeled calibrated date range of entire 2-sigma distribution; grey dashed bars are ages derived from preconstruction contexts; black bars derive from postconstruction contexts. Letters (A-G) adjacent to logs refer to specific dates in Table 1; A-G from Herrmann et al (2014), H-I from Fletcher et al (1996). Note the nearly 1,400 years that separate ages near the base of the mound reported by Herrmann et al (2014;see A-G) from those of Fletcher et al (1996;see H, I), a figure that supports the initial construction at about 300 BC rather than AD 1070.…”

“…Letters (A-G) adjacent to logs refer to specific dates in Table 1; A-G from Herrmann et al (2014), H-I from Fletcher et al (1996). Note the nearly 1,400 years that separate ages near the base of the mound reported by Herrmann et al (2014;see A-G) from those of Fletcher et al (1996;see H, I), a figure that supports the initial construction at about 300 BC rather than AD 1070. (Figure by G. William Monaghan and Edward Herrmann.…”

“…OxCal analysis indicates that the Serpent Mound was likely constructed sometime between 381 BC and 44 BC (with a 95.4% probability), with the highest probability for Serpent Mound construction as 321 BC (see Figure 4b). The analytical framework established by Herrmann et al (2014) was straightforward and based on the temporal and stratigraphic relationship of sediment and soil to the very first load of fill Fletcher et al (1996); 3 median calibrated age (calendar years) based on 2σ probability (Herrmann et al (2014); 4 Calibrated ages usingOxCal 4.2.3; ages in parentheses are OxCal modeled ages (Bronk Ramsey, 2013) using IntCal13 atmospheric curve (Reimer et al 2013); calibrated ages show entire 2σ probability range.…”