One Site, Two Components, Forty-Five Days
A cultural resource management firm holds a 45-day permit to excavate a 2.1-hectare site before a highway bypass. The deposits include a shell midden, two pit features that truncate one another, and a charcoal-rich hearth. Three conventional radiocarbon dates on charcoal have returned 1240±30, 1180±25, and 2430±40 BP. The 2430 determination comes from a charcoal cluster beneath the lower pit floor. The developer's schedule requires a significance determination by day 30, or the alignment moves and the site is capped with fill. The state historic preservation officer will accept a determination only with a demonstrated stratigraphic sequence. The firm's field director wants to drop the 2430 result as an outlier, describe the site as a single late-precontact component, and proceed. A local tribal nation has asked that the hearth be left in place and has requested a monitoring agreement; the permit authorizes analysis but not reburial.
1. Is dropping the 2430 BP date scientifically defensible? What should be done instead?
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Not yet. Charcoal dates the wood, not the burning event; old wood and redeposited charcoal routinely produce ages centuries too early, and this sample sits below the lower pit floor - exactly where redeposited material accumulates. But 'outlier' is a conclusion, not a default setting.
Test it:
- Check the stratigraphy: does the charcoal cluster lie in a primary deposit or in pit fill? Was it sealed by the floor?
- Resample short-lived material (charred nutshell, maize cupule, bone collagen) from secure contexts and AMS-date it.
- Build a Bayesian phase model using the stratigraphic order as a prior. If 2430 BP falls outside the model's expected range, it can be excluded with a stated probability rather than by fiat.
- Date the truncation event: fill from the upper pit gives a terminus ante quem for the lower feature.
Dropping one inconvenient date to fit a 30-day schedule is data suppression. Report all three, explain the model, and state the preferred chronology with its uncertainty.
2. What should the significance determination say, given the 30-day deadline?
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Eligibility rests on integrity and information potential, not on a single component label. Stratified deposits, sealed features, a hearth, and a midden constitute research potential whether the site represents one occupation or two.
Within 30 days:
- Submit the dating plan and an interim stratigraphic analysis (Harris matrix, feature profiles) rather than a premature final report.
- Recommend the site eligible, with a data-recovery research design covering both occupations. The two-component reading, if supported, strengthens the case because it addresses diachronic use and site formation.
- Evaluate avoidance and capping as an alternative if the alignment can move; capping preserves deposits for future techniques.
- Specify what 45 days cannot deliver - full analysis, dating, curation - and request a post-fieldwork analysis period.
A significance determination is a legal judgment with a research basis. It must not be reverse-engineered from the bulldozer's schedule.
3. How should the firm handle the tribal nation's request within the limits of its permit?
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Consultation is expected in spirit and often required in law, but the firm must be precise about its authority. The permit covers analysis, not reburial; promising reburial would be a commitment it cannot keep.
Steps:
- Meet the tribal nation before the hearth is lifted and ask what they want: monitoring, limited excavation, repatriation, or no further work.
- Explain the legal framework accurately. NAGPRA's applicability turns on land status and federal funding; state law and the SHPO may add requirements. Inapplicability of NAGPRA is not a reason to skip consultation.
- Offer what is within power: a tribal monitor on site, a site visit, a voice in sampling, confidentiality for culturally sensitive information, and a curation agreement naming the tribe as consultee.
- Route any reburial request to the SHPO and landowner in writing, and document the response.
Anything less turns consultation into notification after the fact, which is the finding that sinks CRM projects.