Dates and Dating

Many archaeologists erroneously conflate the ideas of age and cultural development and refer to a particular span of time as if every group alive at that time was at the same stage of development. The most obvious example is the “Late Woodland” period as used in North Carolina, South Carolina, and Georgia. In South Carolina and Georgia it is believed that the Mississippian people arrived after about 900AD, and that everyone thereafter was living in the Mississippian Period and presumably, practicing the same lifeways. That is, living in villages, building temple mounds, growing corn, and following hereditary leaders. In North Carolina the Mississippian culture only touched the Southern part of the state, and everyone else continued to live “Late Woodland” lifestyles. So if a person refers to the Late Woodland as if it is a time period considerably different ages can be implied. If the only indication of a temporal affiliation that is used is a term like "Late Woodland" then it is not clear at all what the author is trying to convey.

Fortunately we have access to scientific dating methods that can allow us to independently date contexts containing pottery, and deduce its probable age by association. As stated above, there are three major break points, with a fourth that is more nebulous. To avoid the cultural conflation issue I have split pottery into four time based groups that essentially mimic what has come before, though what others term the Late Woodland and Mississippian are conflated. These are Early (~2500BC to 500BC), Middle (~500BC to 500AD), Late (500AD to 1520) and Contact (1520-present) Periods. The historic or contact period can be split in two, as early contacts (1520-1670) were brief and sometimes indirect, while later contacts (1670-present) were more sustained.

The Early Period includes Thoms Creek, Stallings, Hamps Landing, New River, and Refuge wares. This dates from about 3000BC to about 500BC, when carved paddles were used to form check stamped Deptford pottery. As early as about 1500BC pottery making was getting its start in the Mid Atlantic states, and from its earliest expression surfaces were frequently marked with cordage, nets, or fabric.

Early Period wares with textile impressions likely to be found in South Carolina include the Hamps Landing and New River series (Herbert 2003). Although the introduction of Deptford pottery marks a fairly clear break point, its abandonment a thousand years later is not as clear. By the end of the Middle Period in about 500AD check stamping had largely been replaced by textile marking.

Thus the beginning of the Late Period is marked more by the decline of check stamping than the introduction of anything radical or new. In South Carolina complicated stamped wares associated with Mississippian culture are introduced around 900AD. For a time it was believed that they replaced textile marked wares and their makers, but more recently dates have been obtained that indicate considerable overlap.

The Historic Period is the fourth group. It is somewhat nebulous and should probably be split into pre-1670 (1520-1670), 1670 to 1730, and 1730 to present divisions. During the early Historic Period European impacts were relatively minimal, but after the English arrived in 1670, they were transformational, resulting in an almost total collapse of Native American societies. Little Native American pottery was made after the 1730s, because there were few people left to make or use it. After the 1730s the groups that coalesced as the Catawba, and possibly other "Settlement Indians" made limited amounts of pottery for trade, and this practice continues today.

When David Anderson did his 1975 study he noted that only 14 radiocarbon dates had been obtained for sites in South Carolina. At present some 340 from South Carolina alone are summarized in the project database. About 150 others from Georgia and North Carolina were collected as well. Unfortunately these are often more confusing and misleading than they are illuminating. First, as carbon dating has developed it has been noted that corrections and calibration are necessary. Each new tweak means earlier dates have to be adjusted, and if researchers do not specify if or how they corrected their date, the results can be misleading.

The material used to generate a date can also be problematic. For instance, as David Hurst Thomas explains at length, when marine shell is dated it is necessary to account for the “Reservoir Effect” which accounts for the cycling of earlier carbon from the depths of the ocean to the shells. This is estimated to be about 130 years at St, Catherines Island in Georgia, where Thomas works, but it can vary locally - even on the same island, as the estuary side receives less salt water from the ocean. This can have a significant effect on dates, obviously, and is still not completely understood. Researchers have dated shell and charcoal samples from the same feature and received dates that were hundreds of years away from each other (Southerlin ed. 1997, for instance). Likewise the dates obtained from oyster shell can vary widely depending on whether or not the calibration is applied. This can be seen with South and Widmer's dates for Hanover pottery from Fort Johnson, which fall into the 100-200BC range without, and 200-300AD with the calibration. As a result Hanover pottery was long believed to be much earlier than the bulk of the dates collected on this project. In fact, even the (calibrated) 200-300AD dates are at the very early end of the range. Most dates fall between 270 and 1384AD.

Context is also an issue. The charcoal in a given excavation context is not necessarily associated with the artifacts that are present there. Our dates from a buried, stratified deposit of check stamped Deptford ceramics at 38LX283 (Sandstone Ledge Rockshelter, see page 50) are a good example. In the profile a lens of dark soil with bits of charcoal embedded co-occurred with the ceramics. so it seemed natural to assume that the age of the pottery and the age of the charcoal would be the same. The conventional age was 4230+/-100BP, which is much too early, but when it was calibrated using the then standard Stuiver et al (1993) method it had a 1 sigma range of 3045-2560BC, with an intercept of 2880BC. A more recent calibration (CalPal-online) gives an intercept of 2808BC, while Calib 5.1 gives a 1 sigma intercept of 2876BC. Though they are all fairly close to each other, none of the calibrated dates is anywhere near our conception of the age of Deptford pottery. In fact, they are more in the range we would expected for the underlying Paleo to Archaic midden suggesting a rockshelter cleaning episode.

In several cases dates included in the project database were obtained from similar, permeable or mixed contexts (Blanton et al 1986; Abbott et al 1996, for instance). Sometimes they seem to fit, but in other cases they seem to be incorrect.

So when we discuss carbon dates it pays to consider context as well as correction factors. However, as the database shows, it is not always clear that this has been done. For a single date or single site a 100 year difference is not extremely significant, but when studies are aimed at tracing change in community patterning, as Marcoux (2008), Rodning (2005) and Boudreaux (2009) have done, it is crucial that accurate dates be obtained.

 

SPECIAL NOTE

I have attached a preliminary table of radiocarbon dates that I have collected sorted by the type of pottery from South Carolina associated with the date. This is presented in a simple tab delineated column .TXT file format to allow it to be opened in a number of programs. An expanded list includes dates from North Carolina, Georgia and Florida.

When I began I was blindly collecting whatever the original authors had included with their reports, but soon saw the folly in that. The way that people have reported dates over the years varies widely, and in dating terms, this can mean a lot. For instance, early on there was no effort made to calibrate dates derived from shell for the marine reservoir effect. Later the marine effect calibration was applied to all shell, even freshwater shell, to which the effect should not apply. As it turns out this can throw dates off by hundreds of years. See Thomas 2008 for a good discussion of this issue. So, when possible I have taken the original lab form and re-calibrated the dates with Calib 5.1 (CALIB RADIOCARBON CALIBRATION PROGRAM* Copyright 1986-2006 M Stuiver and PJ Reimer). In the "date notes" field these are marked "Calib 5.1 applied."

I have taken the conventional radiocarbon age, applied the calibration, presented date ranges at the 1 and 2 sigma levels, and abstracted a median age for reference purposes. In some cases only calibrated dates were presented, so I did not recalibrate for fear of introducing additional error. These are noted. In many cases it was not clear whether calibration had been done or not. All of this data is included, so there may be multiple dates for a single sample. I have tried to explain what I did with each. For the non-Calib 5.1 dates it would probably be better for you to refer to the original source if you want to use these dates.

The "Date is for" field refers to the type of pottery, at the ware group level, that is supposed to be associated with the date. This should be approached carefully, as many dates are suspicious, and exactly what they are supposed to date is often unclear. The 7,692BC date obtained from a feature at the Kolb site (38DA75) that contained Hanover pottery is a good example. But the 1,566AD date for Hanover from 38HR243 is also questionable. In other cases dates were obtained for mixed contexts and researchers applied to the type thought to match the age. So, in short, do not accept these dates at face value.