Every now and again, I'll work on a site where I find something that really doesn't seem to belong there, until the context of the item is worked out. This is one such situation, involving a projectile point that seems out of place, but likely seems out of place simply because we don't know as much about the site from which it has come as we would like.
So, I was recently excavating at a site in the central Sierra Nevadas, in an area where the earliest agreed-upon sustained occupation began around 2,500 years ago. We were at a known site, performing boundary testing - where we excavate small holes to see if the buried archaeological materials extend beyond what is visible on the surface, and if so, how far they extend. We were not collecting any artifacts, just noting them, photographing them, and re-burying them in the holes from whence they came*.
During this process, we found a projectile point, probably a point from an atl-atl dart, made out of chert (while most of the waste flakes we found were obsidian). It was of a type not commonly found in the area**, but appeared to be fairly unremarkable otherwise. It looked like a type known as a Borax Lake Wide Stem, but those are very, very old, and I figured it was more likely that I was getting the type wrong than that a site that held features and artifacts that we can confidently date to the last 2,000 years held a point that was significantly older. My boss was out on that day to see how we were doing, and neither he nor I immediately thought anything more of the point than that it should be photographed and we should try to type it when we got back to the office.
On returning to the office, I pulled out my books and articles to try to more accurately type the point. And I kept coming back to the Borax Lake Wide Stem. This was odd, as these points date from 7,000 to 11,000 years ago. So, again, I assumed that I was wrong, and we forwarded the photos to an expert on projectile points.
When the expert responded, he told us that the point is, in fact, of the Borax Lake Wide Stem variety, and that it likely dates to between 7,000 and 11,000 years before present.
Now, keep in mind that other materials on the site date it pretty clearly to the last 2,000 years. So, this point is a bit of an oddity. However, similar points are found in the Great Basin, to the east of the Sierras, and throughout California to the west. So, it is not at all unbelievable that this point would be there, but its presence brings up an interesting question: is it simply an isolate (a single artifact that was dropped and/or may have been picked up and moved by later people, such as those inhabiting the site during the last 2,000 years), or does it represent an earlier component to the site (that is, was there an early site here that the newer site was simply placed on top of)? One confounding element is that the site is located in a somewhat out of the way place, somewhere where later peoples were clearly living, but where traders passing through would be less likely to go. Another definite possibility is that points of this type, being relatively simple to manufacture as compared to some other points, might actually have a much longer period of use than is normally thought (and possibly, the longer period of use is based on the location). Yet another possibility is that a later occupant of the site found this point while they were traveling elsewhere, and brought it back to the site (while this possibility tends to get downplayed in many reports, there is ethnographic evidence of this sort of thing happening from time to time).
Anyway, the presence of this point at this site does not necessarily mean that the site itself was occupied all those many years ago. It's an oddity the meaning of which is unclear. There's no way to know without a more extensive excavation, and we have no idea whether or not we'll get to do it. Still, it's pretty cool to find something unlikely, regardless of the final conclusion.
*This is a pretty common approach. Partially this is an effort to reduce the amount of stuff that ends up being stored in curation facilities and not studied. Partially it is done out of deference for Native Americans who are concerned that materials stay where they are. And, partially, it is a desire to reduce the impacts that archaeologists have on the sites that we study. We may destroyt the stratigraphic context of an artifact, but it's horizontal context remains intact - it may not be much, but it's better than nothing.
Of course, that being said, we still do collect artifacts on many projects.
**The shape and size of a projectile point can be used to figure out who was in an area and when. Projectile points changed over time and not every group used the same sorts, so looking at the points