Saturday, May 10, 2008

On the Importance of Being Precise

Yesterday I posted some of our preliminary results from the surface collection of one of the fields south of Port Tobacco. I've provided an updated version of yesterday's map, this one including the topography of the field, and I've done so to make a point.

When collecting artifacts from a field, it is a simple matter to walk back and forth, collect whatever can be seen, and then list those objects and try to determine their significance. That isn't the way the Port Tobacco team does it. We use a total station (a surveyor's instrument) to map in each oyster shell, potsherd, and stone flake. Not only do we note the object's exact location relative to our site datum (an arbitrary point from which all measurements are taken), we also note its relative elevation.

We use those elevation points to construct a topographic map of the field. With the resulting contours, we can see how the artifacts relate to such landforms as steep slopes. Note the series of oyster shells in the southern part of the southernmost field (the 'Mixed Scatter')...they lie at the foot of a steep slope, which suggests that they have been washed down hill. They may represent an archaeological site, but that site likely lies at the top of the slope in an area now wooded.

The historic site in the northeastern corner of the fields occupies a gentler slope, but even much of that material may have eroded down slope from a site that is situated beyond the field edge and into the woods.

The prehistoric sites occupy a relatively level area, just above a low-lying area to the south, an area devoid of artifacts. What the map does not show, because our measurements were confined to the cultivated field, is the wood edge some 20 ft beyond, and the top of the steep, wooded slope above the extensive marshes bordering the Port Tobacco River. Observe the linear alignment of prehistoric artifacts in the area designated 'Prehistoric Sites.' Those prehistoric sites appear to have been located with reference to the banks of the ancient Port Tobacco River before it shifted westward and before the marshes formed.

Accurate, precise mapping of artifacts is critical to the conduct of modern archaeology. The days of collecting objects and noting which field they are from, or what corner of which field, are over. We need to know precisely where a site is so we do not waste scarce resources at more intensive levels of investigation. And, if we are to call one cluster of material a site and not another cluster, or if we are to date a site to one period and not another, we need the kind of information necessary to justify those decisions to ourselves and to other scientists.


Friday, May 9, 2008

Two Sites Defined

NOTE: Fieldwork for this weekend has been cancelled due to the heavy rain received today!

In the fields south of Port Tobacco we have identified several sites. I'll write about them as we complete preliminary analyses. Two of the sites appear on the accompanying map: one prehistoric, the other late 18th or 19th century.
Figure 1. Map of the surveyed fields. The small symbols represent different kinds of artifacts, the ovals represent the sites that we defined on the basis of artifact concentrations.

The prehistoric site probably represents several small sites that were occupied several thousand years ago during the Late Archaic period. We found a large number of flakes (mostly quartz), several biface fragments, fire-cracked rock, and a Savannah River style projectile point (see below). Other flakes occur throughout the two fields, but they were scattered. We also found a Claggett projectile point in the northeastern corner of the northern field. Oyster shell was virtually absent in the western part of the field and that makes sense: the prehistoric sites likely were occupied before the Chesapeake Bay had reached its current state of development and before marine shellfish were available.

We also recovered a single sherd of aboriginal pottery indicating a Woodland period occupation. It came from near the field edge at the north end of the prehistoric site.

Figure 2. Claggett (left) and Savannah River (right) projectile points represent early aboriginal settlement along the Port Tobacco River.

The historic site was defined largely on the basis of brick rubble. We also recovered several pieces of what appears to be roofing slate. If the structure had a slate roof, it likely was of brick construction. I think it extends northward into the woods and we found only its southernmost edge. The site is difficult to date accurately because only a few datable artifacts (ceramic sherds) were recovered: two pieces of Chinese porcelain, a piece of white salt-glazed stoneware, a gray stoneware of uncertain vintage and a 19th-century whiteware.

The southern field proved to be heavily eroded. We found a cluster of oyster shell, three wine bottle sherds, a few brick fragments, and a scatter of flakes. It is possible that these are all related to an as yet unidentified site between the field and Chapel Point Road.

We will register the two sites with the Maryland Historical Trust as soon as we assemble a few more technical details. The scatter to the south must await further study.


Thursday, May 8, 2008

Rainy Day Tasks

In light of the forecast for considerable rain Thursday night and into Friday, we will suspend fieldwork at Port Tobacco until Saturday. I hope to continue with the survey of the fields south of town.

Of course we continue work when it rains, just not necessarily in the rain. We will complete the site map for the middle field between Port Tobacco and Warehouse Point. Hopefully, we will be able to post it tomorrow.

One warning that should be necessary, but that I will make just the same: those fields are private property and may not be entered without the owner's permission. In any case, I hope that those of you who follow this blog know better than to indiscriminately collect artifacts, especially in the midst of a scientific investigation.

Wednesday, May 7, 2008

New Pre-Revolutionary War Site

I was out surface-collecting with Pete and Elsie yesterday. We found unequivocal evidence of a pre-Revolutionary War site.

Of the hundreds of objects that we mapped and collected, we found no Pearlware ceramics (1780s+), some Creamware (1764+), Chinese porcelain (18th through early 19th centuries), tin-glazed earthenware (18th century), and lots of white salt-glazed stoneware (1720s to ca. 1800).

There are a few later ceramics, but they are so few and scattered that they probably represent a later occupation.

These historic materials are interspersed with lots of prehistoric lithic artifacts, mostly flakes, and two early prehistoric projectile points. There is a fair amount of oyster shell that I suspect is associated with the historic occupation, not the prehistoric. If the latter is as old as I think it is (Archaic), oyster was not available in the area at the time those peoples lived along the Port Tobacco River.

Again, we have a large amount of data to process, so I don't have any images to post at the moment. We also have much more to collect in the field.


Tuesday, May 6, 2008

Cemetery Preservation

Mount Rest Cemetery sits on a hill just south of La Plata and is the burial grounds for Christ Episcopal Church, the same one moved from Port Tobacco in the early 1900s. Most of the stones in this spot are fairly modern, but according to Dave Chapman, cemetery director for the parish, many of the older stones and burials were removed to this site.

My firm, Grave Concerns, was hired by the Charles County Genealogical Society to repair two of the older stones that had broken. This cemetery was vandalized about 10 years ago and was restored, but careless grounds keepers have damaged other stones over time. Another problem is that well-meaning people decided to encase some of the fragile marble tablets in concrete...always a bad idea.

An employee of Grave Concerns mending the gravemarker of Virlinda Stone.

The same stone after reapir.

There are many ways to preserve old burial grounds and just as many things one should NOT do to fix a stone. Like I mentioned above, a marble marker should never be repaired or re-erected using concrete or Portland cement. That material is much harder than marble and will create a snap point for the softer stone.

I will be speaking to the Charles County Genealogical Society on May 15th about cemetery repairs, research, and preservation and I will also discuss the subject one evening during the summer archaeology session at Port Tobacco in June. See ya'll there!

Monday, May 5, 2008

And Yet More Sites...

Yes, Pete and I were out again with Elsie and Carol. We were collecting the field immediately south of Port Tobacco proper and found compelling evidence that the town site extends further south than the current landscape suggests. Aside from one or two historic period sites, we found a good deal of late prehistoric material (Late Woodland).

We also noted that the concentrations of artifacts and oyster shell paralleled a linear area, poorly drained. I had noted it last year and suspected it might be a relict stream channel, and it may be; but it also might be the road leading south from Port Tobacco to Warehouse Landing.

We have a great deal of artifact washing and cataloguing, and lots of drafting to do, but hopefully we will have something more definitive ready by the end of next week. I'll try to snap a few photographs tomorrow.


Sunday, May 4, 2008

Sites Found in Fields

Sunday was a beautiful day to spend in the fields south of Port Tobacco. Elsie, Pat, Frank and Carol joined Pete, Scott and me for a day of controlled surface collecting and precision mapping. It will take a week or so to get everything washed and mapped, but I think we have two 18th/early 19th century sites and at least one relatively well-defined Late Archaic site.

We'll be out again tomorrow surveying the field immediately south of Port Tobacco.

That's all for now. My neighbor has a nice bowl of risotto waiting for me.