Monday, June 30, 2014

The Archaeological Potential of a Burned Capital

Today's post comes to us from Kevin Bradley, a former intern for DC's Historic Preservation Office through the Washington DC District Leader Program (DLP). Kevin recently completed his Master's degree in Public Anthropology at American University, and is currently working for JMA in Philadelphia. While he was still with the DC HPO, he addressed a problem familiar to every urban archaeologist: how much has the intensive development of the modern landscape obscured (or obliterated) the physical remains of the past?

The Archaeological Potential of a Burned Capital 

Recently, the Washington, DC Historic Preservation Office (DC HPO) Archaeologist, Dr. Ruth Trocolli, and her staff incorporated the GIS Cut/Fill tool in their efforts to identify archaeological sites within the city. Since August 24th and 25th of this year will be the 200th anniversary of the burning of the capital by the British Army, we decided to explore a few notable sites from the invasion in 1814 to find out what this new analysis would add to an understanding of the city’s history.

One of the main responsibilities of the DC HPO Archaeologist is to ensure the integrity of the city’s archaeological resources. Quite often this means providing information and as much guidance as possible to archaeological companies contracted to conduct studies within the District, such as historic documents, maps, references, and geographical information systems (or GIS) data. GIS, in particular, is an extremely valuable resource for archaeologists. The DC HPO uses GIS to map previously discovered sites and locations of surveys, as well as landscape features. In other words, it helps archaeologists keep track of the ever-changing urban environment in Washington, DC, including the construction of roads, bridges, and buildings, the installment of numerous utilities, and the changing elevations and shorelines of the city. All of these activities may have an impact on archaeological remains. The GIS tool, “Cut/Fill”, helps archaeologists understand these changes to the landscape even better.

What is a Cut/Fill analysis? It is a simply a method of calculating the elevation changes in a landscape over a period of time. Most cities are not built on unaltered terrain. Buildings, roads, and other infrastructure are easier to build on relatively flat surfaces. Therefore, higher elevations, such as hills, tend to be leveled and low lying spots, like valleys and streams, get filled. Comparing the elevations from, say, an 1888 topographic map and a current topographic map may tell us how much earth has been cut away or added in between the two periods, potentially destroying or preserving buried archaeological features in the process.

Battle of Bladensburg (Copyright Gerry Embleton; Courtesy NPS/Star Spangled Banner National Historic Trail)
Washington, DC, like every other city, has changed dramatically since 1814. While excellent archaeological work has been conducted around the city boundary on the site of the Bladensburg Battlefield, little work in the District has focused on the British march through the city. Performing a Cut/Fill analysis of broad areas where these activities took place will help determine if archaeological sites are likely to be present and provide some idea of their integrity. What follows is the result of performing this analysis on a few select sites and what the results indicate about potential material remains.

Eastern Avenue Ortho 2012 (DC HPO GIS)
1888 US Coastal and Geodetic Survey (National Oceanic and Atmospheric Administration (NOAA))
The American defeat at Bladensburg on August 24, 1814 completely opened up the nascent capital city to the British. Part of the battle (or at least the retreat) spilled across the current DC/MD boundary. As you can see from the 2012 Orthographic aerial photograph (above), this portion of Washington, DC is heavily urbanized. Fort Lincoln Cemetery (top right of the photo) lies on the Maryland side of the boundary line and abuts the District along its southwest border. The second image shows an 1888 US Coastal and Geodetic Survey map overlaid on top of the 2012 photo. You may be wondering why a map produced 74 years after the event is being used for comparison. Unfortunately, reliably detailed maps of Washington, DC are few and far between prior to about the Civil War. The 1888 map represents one of the more comprehensive early maps. In order to determine elevation change, topographic lines from different time periods must be compared. Once two sets of topographic lines are obtained, a rendering of the terrain can be produced within the GIS program and a Cut/Fill analysis will determine where changes in elevation have occurred.

Eastern Avenue Cut/Fill (DC HPO GIS)
Eastern Avenue Area of Interest (DC HPO GIS)
The image above is a simple outcome from running the analysis. The red represents areas that have been filled (where the soil has increased in volume) and the blue represents areas that have been cut (where the soil has lost volume). Grey represents no change, which you can see from the image, is not common. The degree of cut and fill activity represented in this image is unsurprising given such a developed area. Noticeable in this map are features, such as Bladensburg Road located in the northwest of the cut and fill area, indicated by a thin line of fill, and a creek, present on the 1888 map in the southeast corner, which has since been filled, indicated by the large red blotch in its place. The yellow box in the second image represents an area of interest for the DC HPO archaeology staff – a presumably relatively undisturbed area just across the city boundary from Fort Lincoln Cemetery, where archaeological remains of the battle were previously located.

The British pursued the fleeing Americans southwest along present-day Bladensburg Road until they reached the city gate. Though this area is not specifically identified on maps or in primary sources, it is assumed that the British halted and camped just outside the current intersection of Florida Avenue (then Boundary Street), Bladensburg Road, Benning Road, Maryland Avenue, and 15 Street. The image below was created from the same 1888 topographic map as the previous Cut/Fill analysis. Again, we can see sporadic episodes of cut and fill throughout the area, though lines clearly follow roads and buildings at times. The partially transparent close-up image shows how areas, especially under ball fields and buildings, have been graded to make level surfaces. If you’re wondering why this particular map took such an odd shape, it’s because the production of any map is reliant on available data (see the 1888 map, below). The notch omitted from the Cut/Fill map represents the former site of the Washington Brick Company where no topographic lines were recorded, though the nature of work at brick yards virtually ensured that any archaeological deposits would have been destroyed.

British Encampment Site (DC HPO GIS)
British Encampment Site, Close-Up (DC HPO GIS)
1888 US Coastal and Geodetic Survey, British Encampment Site (NOAA)
While the main force of the British army was camped outside the city gate or still marching down the road from Bladensburg, General Robert Ross, Rear Admiral George Cockburn, and a handful of British soldiers continued down Maryland Avenue towards the US Capitol building to discuss the city’s surrender. A few hundred feet prior to the East Lawn of the Capitol, the British were fired upon from a structure located on the northwest corner of the Constitution Avenue and 2nd Street, NE intersection – the current location of the Sewall-Belmont House. After razing the building, the British 3rd Regiment entered the city and proceeded to burn several public buildings (and a couple private structures) over the course of the following 24 hours.

U.S. Capitol after burning by the British (George Munger, 1814, Library of Congress)

Perhaps most infamously (for Americans), the British showed no hesitation in storming up Capitol Hill and setting fire to the still incomplete government structure that sat atop it, incinerating the House of Representatives, as well as collections that comprised the Library of Congress (LOC). While the British soldiers supposedly set up camp on the East Lawn of Capitol Hill, General Ross established his headquarters in the private home of Dr. James Ewell; an end row house on the northeast corner of 1st and A Streets SE (the former intersection can be seen in the 1872 map below).

Carroll Row, ca. 1880 (Levin Handy, Library of Congress)
1872 Bastert-Enthoffer Topographic Map (Library of Congress)
The 1888 US Coastal and Geodetic Survey used to produce the two previous Cut/Fill maps did not record elevation data in the city proper (the historic federal city). Therefore, the 1872 Bastert-Enthoffer Topographic map (above) was used in its place. The 1872 topographic map also provides elevation data at five-foot intervals; though, you may notice that the topographic lines are not as detailed as the 1888 map, meaning fewer elevation points were likely obtained to create those lines. Hence, the resulting Cut/Fill map may be less precise in its measurements than previous maps.

Capitol Hill Cut/Fill (DC HPO GIS)
Nevertheless, the Cut/Fill map of Capitol Hill (above) produced expected patterns (i.e., cut and fill along roads and the edges of squares). If we trust the reliability of this map, though, a large swath of the East Lawn of the Capitol has been cut away, unfortunately, removing any potential evidence of a campsite. Dr. Ewell’s house, however, appears to be located in an area of fill. The Cut/Fill map, though, may not always tell us everything we need to know…

Library of Congress construction, 1889 (Levin Handy, LOC)
The image above shows the construction of the current LOC building in 1893 on the site where Dr. Ewell’s house once stood. Notice the depth cut for the foundation of the LOC most assuredly affected any potential archaeological remains. The point is that while a Cut/Fill map may indicate an area of fill, archaeologists must incorporate other research to determine whether intact buried historic layers remain.

These are just a few of the sites related to the British invasion of Washington, DC. From the Capitol, the British spread out through the city and burnt or ensured the destruction of other notable structures, such as the President’s Mansion (White House), the Navy Yard, the US Treasury, and others, before exiting the city on the night of the 25th.

The DC HPO is in possession of few confirmed artifacts related to the War of 1812.  Archaeology presents a unique opportunity to inform current DC citizens of and connect them to this extremely formative and often overlooked event in the city’s (and country’s) history. The Cut/Fill tool is a valuable first step in exploring the archaeological viability of these sites. Of course, archaeologists will never know the validity of any desktop analysis until shovels are actually put in the ground, but the potential of this GIS tool to predict intact site locations seems promising.

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