The Ground Washington Walked On

Areas of Excavation

As we move into this final week of digging, we are offered the rare opportunity in this area of excavation to be able to dig an untouched portion of the 18th-century ground surface. Since we completed the investigation of the three anomalies we set out to look at this season, we have moved on to a different aspect of the site.  The ten feet long corridor that was the location of last year’s “L”-shaped Block 2 excavation is believed to be the location of a historic fenceline that was still standing during the 1970’s excavation. In fact, there have been several different fence lines present on this landscape since the encampment. These fence lines can been seen as evidenced in this Excavation Unit from the 2009 field season:

Post Holes

Post holes are another type of feature archaeologists can use to identify cultural occupation. Post holes generally consist of two components, the post hole itself and the post mold. The post hole represents exactly what it sounds like, the hold that was dug to put the post in the ground. The Post mold is the remain of the post in one form or another. In the above picture, you can see two different examples of a post mold; one where the post has been pulled and an open void was left in place and one where the post most likely rotted in place or was filled back in. Judging by the make-up of these post holes, they each represent a different fence line installation.

With the presence of one of these fence lines in the ’70s, archaeologists were not able to place excavation units where the fence line stood. As a result, this has left us with a relatively untouched section of the site. When we excavate these areas of the site, we encounter three distinct layers.

Intact Stratigraphy

The first two layers represent different fill episodes, most likely related to the landscaping of the area around the Headquarters building. What lies below those two fill layers however represents the intact cultural occupation of the landscape.

Volunteer Rich Helps Us Excavate Layer III

Layer III represents the ground surface that George Washington would have walked on during the encampment period. As I mentioned in an earlier post, this layer has proved to be the most artifact rich layer of the entire three years of excavation. What we see represented in this layer is evidence of what is called, “Broadcast yard scatter.” In addition to disposing trash in subterranean pits, it was also common in past to just walk out the back door and cast your refuse out into the yard. Since we are located behind the building, we are located exactly where we would expect to find this type of refuse disposal. If we had a larger area of intact context, it would actually be possible to map a fan like pattern of refuse from the rear portals of the building. Unfortunately, due to the nature of the site this is not possible.

With this being the final week of excavation for this field season, we will soon be moving into the laboratory phase of the project. This involves the cleaning, cataloging, and analysis of all the artifacts recovered from this year’s field season. Now that excavation is wrapping up, we will start to show you some of the wide variety of interesting things we have been finding during the excavation this year. Stay tuned as we update you on all of the things that “belong in a museum.”


Anomaly #3 and A Lesson in Soils

Another exciting week has gone by as we continue the excavations at Washington’s Headquarters. After identifying anomaly 2 as being a French drain, we have now moved on to investigate anomaly 3. Located southeast of anomaly 2, this target sits just east of anomaly 1, with a large tree separating the two. Once again, we thought this anomaly could be very promising in our task of trying to find the privy. Our hopes were dashed as it became quickly evident what we had here.

First, let me explain briefly how we as archaeologists identify what we are looking at. Archaeology requires various levels of knowledge that are borrowed from other disciplines, to allow us to accomplish an excavation. One of the most important disciplines we draw upon is the science behind soils and their development. A keen understanding of how soil deposits form, along with a sharp eye for soil color and texture is a very important aspect of archaeology. When excavating a site, archaeologists do not just dig straight down. Instead, we follow the natural stratigraphy of the soil; excavating layer-by-layer.

Each layer of soil can represent a single context of time and is highly important for an archaeologists understanding of a site and it’s formation. A key law that archaeologists deal with is the Law of Superposition, which states that in any undisturbed sequence of layers, the youngest layer is on top of the oldest on the bottom; each layer being younger than the one beneath it and older than the one above it. However, previous disturbances to a site can start to blur this definition. The area we are excavating next to Washington’s Headquarters is one such case.

Since this area was previously excavated in the 1970’s, the portions of the ground that earlier archaeologists opened up no longer have their original soil deposits intact. Instead, all of the original soil layers that were deposited over time have been churned up into one single, heterogeneous layer. This can be seen in the following illustration:


An Example of Stratigraphy

Section A represents the natural topsoil layer, a mixture of the natural organics (leaves, detritus, etc.) that have been deposited over time. Section B represents a portion of an excavation unit from the ‘70s. If you look closely, you can see spots of discoloration throughout the soil deposit. This differs from Section C, a natural homogenous soil layer, in that it represents the mixing of different layers. Section D is as far deep as we will excavate the natural stratigraphy. The subsoil is a clay-like layer that was never culturally occupied (it represents the highest layer below natural soil development).

Of the four units we place over anomaly 3, we opened the two southern most units first. As we got through the topsoil layer, it became quickly apparent that we were looking at two previous excavation units from the ‘70s excavation. Reviewing what records we have from that excavation, it seems as if these units represent two 5 feet by 10 feet units. As a result, we will not be able to see the complete units in the area we have open. The units were oriented as such:

Units MM, NN, OO, PP

Previous Excavation Unit Excavated

Once we removed the fill from the excavation units, we did find the anomalous reflection located below these units. Located on the western half of the excavation units was a round dark stain in the subsoil. Since it’s positioned in the subsoil, a culturally devoid layer, it means someone had to put it there.

Feature 41 Unexcavated

Feature 41 Bisected

Upon excavation of Feature 41, all we found were rocks (lots of them) and 19th-century cut nails. We are not sure what this pit once was, but whatever it is, it did not yield a lot of information as to it’s origin. Now that we have investigated the three anomalies we set out to look at, we will move on to excavating portions of the yard that we left untouched by previous excavations. During last summers excavation, we investigated 4 units like this. In these units we found intact portions of the 18th-century yard surface. That layer proved to be highly lucrative for 18th-century refuse. Hopefully we will have something similar again this year.

As a side note, we had an unfortunate run in with Mother Nature this past weekend. Despite our use of both a tent and plastic to cover the site, sometimes there is no stopping the power of water. Luckily, we were done excavating and recording the feature.

Feature 41 vs. Mother Nature

Do not worry though. We have top men on it. Top… Men…

The Limitations of GPR

We hope everyone enjoyed their Fourth of July Holiday. Things have been progressing very quickly on site. Since we started excavating this season, we have already managed to break ground on all three anomalies identified during the end of the 2010 field season. Unfortunately, as with any ground penetrating radar (GPR) survey, nothing is exactly what it seems.

After finishing the excavation of the 19th-century daub pit we identified in the first week, we moved on to investigate the next anomaly. The second anomaly is slightly northwest of the location of the daub pit.

Anomaly 2

As you can see, the second anomaly shows up as a very distinct signature on the GPR results. It is at this point that we as archaeologists encounter the limitations of this type of survey. GPR is an amazingly helpful tool for archaeologists. It provides a fairly quick (when compared to the labor-intensive method of shovel testing) and non-destructive way to examine what is potentially below the ground surface of a survey area. The problem is, GPR only provides us with is an image that displays areas which differ from the natural make-up of the subsurface. To investigate these anomalies, we have to “ground truth” them. Essentially, this means excavating them to physically expose them. Once we can see them, we can analyze them based on their shape, form, and the artifacts associated with them to determine what they are.

Once we excavated the second anomaly, it quickly became obvious that we did not have an encampment related feature:

Anomaly 2 - French Drain

The gravel channel we exposed turned out to be a French drain. This was probably installed sometime during the late 19th/early 20th-century to deal with the constant drainage problems the Headquarters area exhibits. It was quite important that we open an excavation unit around this anomaly. There would have been no way for us to really know what was beneath the surface without having excavated it. What exhibited itself as a strong signature on the GPR proved to be something other than what we were looking to encounter under our research purposes.

The French Drain is still an important find though. While we may have a specific interest in finding the privy associated with the house, the location of this French Drain is still important to the site as a whole. Having located this new archaeological feature has provided us with more information regarding the use of the Headquarters site as a whole during these last 234 years.

All was not lost however. In excavating the fill surrounding the French drain, we managed to find the first definitively Revolutionary War artifact of this season.

.70 Cal. Musket Ball

This musket ball directly relates to the use of this landscape by the military during the winter of 1777-78. The ball measures .70 caliber, which is perfect for the British Brown Bess (in use by the Continental Army) or US made muskets (like the Committee of Safety muskets) modeled after the Brown Bess. The musket ball does not seemed to have been fired, however is does bear scrape marks along one side. It was truly an exciting find.

Stay tuned for more updates as we explore more of the area surrounding Washington’s Headquarters and remember, do not cross the seal…

2011 Excavations v3.0

Welcome back to another exciting year of excavations at Washington’s Headquarters at Valley Forge! My name is Jesse and I will be your guide through this year’s blog of the dig. This is my second official year with the excavation, although I have been involved from the beginning. This year’s crew consists of Joe Blondino, who will be overseeing the project once again. Also, new to the crew this year is Matthew Kalos, a colleague of Joe and mine at Temple University. We are excited to be given the chance to once again excavate at Washington’s Headquarters. It is not often that archaeologists are given the opportunity to excavate sites dealing with such elite figures in American history.

2011 Excavation at Washington's Headquarters

With this years excavation we are taking a different approach to the site. We cheated. In the previous two years of excavation at the Headquarters we were essentially digging blind; not knowing if we would find any evidence of cultural occupation below the surface. We call this, exploratory excavation. At the end of the last field season, Pete Leach of John Milner Associates generously donated his time to us to conduct a Ground Penetrating Radar (GPR) study of the backyard of Washington’s Headquarters. GPR works by dragging a radar antenna across the ground over a measured grid. As the GPR passes over the ground surface, it emits a radar signal into the ground. This signal is then reflected back to the GPR setup by what is below the surface. Different subsurface features reflect the radar signal back differently.

Specifically GPR can be helpful with looking for possible subsurface structures or evidence of ground disturbances such as pits, wells or in the interest of this year’s excavation, privies. This is what the GPR results look like:

GPR Results

The grey areas on the GPR survey represent the natural reflection of the undisturbed ground. Each of the black areas represents some sort of reflection that is different from the natural soil. These black areas on the survey results, known as “anomalies,” are what we as archaeologists are really interested in. To date, a Revolutionary War period privy associated with the Headquarters building has never been found.

From this survey, we have isolated three areas of interest for this year’s field season. The first area of interest that we took a look at proved to be an approximately 6 foot in diameter, circular pit feature.

Feature 37

Just exposing the feature does not tell us anything about what it is or what it may contain. To gain the most information out it, we need to remove the soil from within the hole. Using the subsoil as a guide, we only excavate the dark “feature” soil from within. Once we got in to it, it became quite obvious that this feature had been excavated during a previous excavation in the 1970’s. Luckily for us, their grid did not cover the feature entirely. As a result of this, about one quarter of the feature’s original stratigraphy was still intact.

Feature 37 Bisected

Feature 37 Original Stratigraphy

The outside wall was coated in a thick layer of mortar in addition to the large chunk still remaining in the base of the unexcavated section. We interpret this feature as being what is known as a daub pit. When mixing a large amount of mortar for chinking a log cabin or re-pointing a house, it is impractical to carry around a large vat to mix the material. The easiest method is to dig a pit to mine material and then just mix the mortar mixture inside of the pit. Unfortunately, the feature turned out to contain mostly 19th century artifacts. It seems as if this pit probably relates to one of the later cabin reconstructions at headquarters, possibly the 19th century dining cabin reproduction.

Do not despair; we still have two more anomalies to explore. Stay tuned for a next post as we explore the second anomaly. Until next time, “We do not follow maps to buried treasure and X never, ever marks the spot.” –Indiana Jones


An exciting Saturday!

Well, in between all the press visits, and crazy media frenzy, we actually continue to dig, too!

On Saturday we continued with our second excavation block (aptly dubbed “Block 2”) up on the rise behind the headquarters building.  Joe believes that within the layers of this deeper deposit we can see buried plowzones, layers of soil that were once the ground surface in times past.  Because these soil deposits are deeper, but still with evidence of human occupation, we are finding a much richer series of artifact deposits as well.
This is evidenced by an abundance of ceramic sherds, from a variety of time periods, both 18th and 19th centuries, and by other objects like a musketball, large pieces of food bones, and a thimble.  Most of these things were found during the weeks we’ve been in Block 2, with every unit yielding different and exciting things.  Perhaps the most exciting finds from Block 2, however, came out on Saturday!  There was a fragment of a bone utensil handle; two of which we found last year, so we will have to do a comparison.  As well, there was this:

White Clay Tobacco Pipe

This is the back of the bowl of a white clay tobacco pipe with a partial maker’s mark stamped on it.  But wait, it gets better:



Now before you get too excited, no, this does not necessarily mean “George Washington”.  This is a particular type of pipe, and the W and G stamps reveal its manufacturer.  Since we are finishing up out in the field, I don’t have answers for you yet – no, we don’t know the name of this manufacturer.  However, you can be sure that once the lab portion of this project begins in earnest, Katie will be on the hunt, and we’ll be sure to let you know what she finds out!

I don’t want to squash all dreams, so I must say that it is possible that General Washington could have had personalized tobacco pipes – he was, after all, Commander-in-Chief of the entire Continental Army.  However, until we can confirm beyond a shadow of a doubt that this is the case, we are not willing to say that at all.  For now, we are working on the assumption that the stamps on either side of the heel, the W and the G, and also the stamp on the bowl (in which only part of the W is visible) are indicative of the pipe maker only.  After all, if these marks we meant to represent the General, wouldn’t they be ordered “G” “W”?

Nonetheless, if this is something that strikes your fancy, please leave a comment and let us know!  We want to make this blog interactive – if there is something you want to hear more about, then say so!
We will be updating with at least one more entry about the field portion of the project as we wrap up, but look for more posts as the artifacts are processed and cataloged, and as always, thanks for reading along!

We’re in the news!

Hey everyone, look!  6abc came out today and did a FABULOUS job reporting on our excavations.  Check out the video on their website:

It couldn’t have gone that smoothly forever!

We have had a BUSY couple of weeks!  We’ve had visits from all sorts of media people, and we look forward to our local abc channel (shoutout to 6abc!) coming out tomorrow.  Hopefully you’ve been able to read some of the articles (they are almost all linked in previous posts), and if not, you should soon, the Associated Press picked up our story today!

In the meantime, these past two weeks have been very busy in other ways as well; what with alternating ridiculously hot temperatures and ridiculously drenching rain, we haven’t had much time outside.  So what do you do when you get rained/heated out?  Labwork!  And volunteer juggling!
Here are some of our highlights:


This day was unimaginably hot – one of those 103 degree days with a heat index up in the 110s.  We tried to cool down in the field lab (read:garage) with fans going.


These little ones came right up to the grass outside the door!  The heat didn’t seem to bother them, they were in the shade.  It’s fawning season at Valley Forge, so if you spot one, remember: don’t touch any fawn you see; its mother will have nothing to do with it after it smells like you!  Also, if it’s laying down, don’t worry, it’s most likely not hurt – they need to rest a lot when they’re this young, so please, leave it alone, the park officials know the babies are here and they are keeping their eyes on the whole population!

Statue placement

Last Thursday was also a very important day!  We got a break from our morning excavation to go see the placement of this very important statue.

George statue

The General has returned

Welcome back to HQ, General Washington!  Now he quite literally watches over us in the field lab.

Between the heat and the rain, we did get back out into the field for a little while!

Drawing the feature

Remember folks, record-keeping is the archaeologist’s most important job!

Then the rains came.

Sometimes, when you *know* you’re going to be in the lab, you immediately choose ways to amuse yourself.  This day  was one of those days – Here’s Joe’s idea of how to get water for labwork:

Stick the tubs out in the rain!

Ewww – here’s a closeup of Valley Forge’s rainwater….don’t look up and open your mouths, people!

Yucky water close

Yep, Saturday was quite…..wet.  Here’s what it looked like when we came back Tuesday morning:

Bail Out!

It seemed like the site was a swimming pool…

Feature flood

…and that’s definitely bad news when only HALF of the feature has been excavated!

Damage control

Controlling as best we can when we’re digging in a drainage swale!  Sometimes you can’t help it, you’re in low ground and that’s the way it is.  Still bad news for the units!

Later, we needed to erect a new shelter, because the first frame up on the hill had buckled, merely due to the weight from over 5 hours of steady, driving rain.  Unfortunately, our new shelter and our old awning didn’t match: the shade is bigger!

What to do?  Here is our ingenious solution:

Full water bottles make great weights!

With the help of a couple of our ingenious volunteers, we decided to fill and use water bottles as weights, to pull the tarp tight and to make certain that should any further rain come, this roof will NOT hold it, it will roll right off.  So far, so good!

And to finish out the week on a good note, we have started to excavate our fourth and final unit in Block 2 – Unit DD.  Because of the interuption this week, we may just go our for a few days next week in order to finish up.  Stay tuned!