Dig Diary: How to Section a Posthole

by Eric Deetz, Time Team Archaeologist

To me, the most exciting find at Fort Raleigh was the line of possible postholes found on day three of the dig. Archaeologists from the First Colony Foundation had surveyed the area known as Hariot Woods before and found a few artifacts that could date to the late 16th century. We found a number of artifacts from that time period as well. While artifacts are great, they are small and portable, so a few fragments of busted pottery doesn’t mean you have found the site of the Lost Colony. Postholes are a different story. They would have been evidence of construction, so the discovery of architectural remains gives us as archaeologists an area to focus on.

Any time something disturbs the earth deeper than the topsoil it leaves a tell-tale stain in the soil. In the case of postholes, you can see where the post was buried in the ground. Not all postholes are evidence of buildings. Palisade fence posts, flag poles, and animal enclosures would all leave similar stains, though not in the same pattern.

One way to learn more about a posthole is to section it, or dig out one half. By exposing and examining a cross section of the stain, archaeologists determine if it is in fact a posthole and not something natural like a gopher hole or tree root. If the soil conditions are right you should be able to see the posthole (evidence of the digging of the hole) as well as the post mold (evidence of the post itself) where it either rotted in place or was pulled out and different soil replaced it over time. It is important to dig the posthole and post mold separately. Any artifacts found in the posthole date to the time of the construction of the building and likely fell in when the post was being buried. And since artifacts and posts can’t occupy the same space, any artifacts found in the post mold date to after the destruction of the building or the removal or rotting of the post. At Fort Raleigh we only sectioned one possible posthole.

As Dave Hazzard sectioned the posthole, we were all watching to see if it was deep enough to be a posthole and if there was a post mold visible. It was plenty deep enough but there was no visible post mold. Personally, I was convinced that it was a posthole even though there was no obvious post mold. Many of the postholes I studied at Jamestown looked exactly like this one. The sandy soils on Roanoke Island make it much harder to read the soil stains. The edges aren’t as clear as they would be in soils with more clay in them. My colleagues that have worked on the island for years were hopeful but a little more cautious.

Other information can be discovered from digging the postholes from a building. There are many ways to construct a building using posts in the ground. By studying all of the postholes, archaeologists and architectural historians can sometimes determine how the building was constructed. In my experience at James Fort in Virginia, we were able to trace the building techniques used at the site to an area in the east of England.

More work is needed at the site in Hariot Woods. To learn more about what we uncovered during the Time Team America dig, the rest of the area needs to be uncovered to see if the posts are part of a building and if they date to the right time period. If they turn out to be structural posts it will be a major step in locating the Lost Colony.