Over the last few weeks, work on Dating Iroquoia really kicked off in earnest. Megan, a research assistant with our University of Georgia team, flew to Ontario to collect samples for our first round of radiocarbon dating, which we hope to submit before the end of the year. The sites we were sampling from were housed at 4 different facilities across the province: University of Waterloo (Waterloo), University of Toronto Mississauga (Mississauga), ASI Archaeological and Cultural Heritage Services (Toronto), and Sustainable Archaeology McMaster (Hamilton).
In all, we collected about 130 samples from 9 sites. This might sound like a lot of samples (and, to be fair, it is!) but we need to date many secure contexts from each site to really understand its internal chronology, which will then help us understand how the sites fit in time in relation to one another. We also collected a few more samples than we strictly need for the first round of dating, so that we have more samples on hand to date if we are able to.
The vast majority of the samples we brought home were carbonized maize kernels (Zea mays), although we also ended up with some maize cob fragments, some bramble seeds (Rubus sp.), a hawthorn seed (Crataegus sp.) and some beans (Phaseolus vulgaris). We mainly targeted the carbonized remains of short-lived plants, and here is why: we know that annual plants were only alive for a short period of time, which means that the time difference between the “oldest” carbon and “youngest” carbon in each kernel or seed is not very large. This reduces the chances that the carbon we end up dating represents the plant’s early life, rather than the time at which it was harvested and died.
We also collected two other kinds of artifacts for radiocarbon dating: animal bone and charcoal. These materials can provide dates that are just as precise as botanicals, but we have to be very careful in our selection of samples. For animal bone, we had to make sure that we only sampled bone where we could absolutely identify the species of the animal it came from, and we couldn’t sample from any species that are aquatic, or which consume a lot of aquatic resources. This is because of the marine radiocarbon reservoir effect,which traps older carbon 14 in deep water. This means that radiocarbon dates on organic material from aquatic species (like shell or fish) or species that consumed aquatic resources (like raccoons or some birds) require corrections, which aren’t part of our current research plan– although that would be an interesting and useful direction for future research!
For charcoal samples, we selected pieces of bark or chunks of charcoal that otherwise include the outermost rings of the tree, which formed closest to when the tree died. Charcoal is a great material to use for radiocarbon dating, because it is often abundant on archaeological sites. But, because trees grow out in successive layers, there can be a difference of hundreds of years between dates taken from innermost and outermost rings of the same tree. We’re interested in when the tree died (and was presumably used by the people who felled it), so we were looking for those outermost layers.
This is just the first collection trip for the project. Samantha, the team’s Cornell-based research assistant, is travelling to the Rochester Museum and Science Center in Rochester, New York later this week on a sample selection scouting mission, and she’ll be collecting our first round of New York samples from that facility soon.