By Steven J. Filoromo, RPA, TerraXplorations, Inc., Baton Rouge, Louisiana

Over the course of history, bayous are subject to constant shift. The rate of change now is exceptional. In response, some historians working in southeastern Louisiana are developing novel ways to comprehend the changing environments and their history in danger.

Discusses of Louisiana’s swamps and bayous invoke images of shifting, crazy or rustic landscapes. Spanish moss can often be seen in these images as pine elbows make clear pathways for flat boats to cross while still water hangs over them. One can picture the variety of birds calls that echo through a relatively isolated wood while a sea of lovely green forests directs one’s way through it.

A water of sugar rises above swamps and bayouses in agricultural areas set up from the Mississippi River’s contemporary river system. However, this relatively rural landscape is a substantial cultural resource. While difficult to navigate then, these waters provided the same channels where enslaved people formed networks towards freedom during times of slave tyranny, and others including, but not limited to: Isleños, Acadians, and the ancestors to present Chitimacha, Coushatta, and Houma ( to name a few ) who used these waterways to carry items and ideas. Archaeologically speaking, probability modeling relies upon data that, not to the researcher’s fault, does not consider traditional environments, land use, and other economic data that may not always appear within ancient topographical sources. Archaeologists may suppose relative balance over time, which is the main problem with studying towns in these environments. The bayou’s program is not a constant one. We are left with the opportunity to create innovative ways to identify this history in danger in the face of a changing environment that suffers from major losses to territory and history. Subsequently, we can use one of these techniques: deep seismic surveying.

Find 1. Sugarhouse remains in the backswamp, Ascension Parish. Photograph by Steven Filoromo, July 2022.

My coworkers and I are fortunate to have had the opportunity to use magnetometry at various locations in southeastern Louisiana. A special kind of deep seismic surveying is magnetometry. A total of two meters of geology is condensed within an atemporal two-dimensional photograph to create a mosaic of natural and cultural functions. Things like remnant streams, environment modifications, hearths, structures, and more may appear. While these distinct cultural features are typically the subject of archaeological research, locations of relict landforms like ancient bayous or relict streams ( coulees in Acadiana ) also matter for understanding landscape changes. These characteristics appear in electrical data in different ways depending on mingled variables. In a fundamental sense, sediment layers ‘ ability to be magnetized from an applied field ( magnetic susceptibility ) and their residual ( remanent ) magnetization from an external field are both affected by the magnetic gradient. These variations in the gradient are significant because relict channels exhibit different remanent magnetization, which contrasts with the surrounding environment and cultural characteristics ( see Stele et al., 2004 ). 2020, Heller &amp, Evans 2002 ).

We conducted a magnetometry review prior to any additional ground disturbance during recent historic excavations in Iberville Parish, where we were assessing the viability of a large Coles Creek community ( Phase III data healing ) and determining the viability of a large Coles Creek town. We covered about 3.3 acre for the sugarhouse, and at the Coles Creek time community, we surveyed 7.33 hectares. Thankfully, both sites are set up from the river exactly at the same elevation within the adjacent sugar fields. For the sugarhouse, there were very few indications of any specific ethnic features, whereas, at the town, there were many anomalies related to structures, a traditional road, and many ditches. Between 2 and -2 nT, or nanoTeslas ) magnetic variations, subtle contrasts were notobservable between the two datasets. The boundary between the fields and the bayous was defined by a low-magnitude negative magnetic variation that was prevalent between both locations. The difference between the two locations was that the former bayou at the village’s interior had more obvious, subtle anomalies with positive magnetic variation.

Figure 2. Magnetometry data at the village and sugarhouse.
A number of mechanically excavated trenches were used to generally locate the former bayou channel during the sugarhouse excavation. Bayou soils have more clay and darker colors, whereas soil textures and colors were noticeably different. Similar patterns were observed in the village. Given the size and nature of investigations, we could delineate the bayou as it crosscut the village fully. Significant amounts of terminal Coles Creek ( ca. 1902 ) were present in the areas of more positive magnetism within the bayou. AD 1200 ) ceramics. Given the nature of fired ceramic production and the volume of these materials, the areas within the bayou have surprising higher magnetism levels. It became clear that this waterway had a significant impact on the village’s layout during the village’s excavations. A distinct shared communal area with sheet middens surrounding several smaller neighborhoods that were concentrated on the sides of the former bayou was marked by massive pits and several hearths.

Figure 3. A targeted area of the village is the result of a portion of excavation.

Although the village’s proximity to the village offers insight into how the area was used prior to French colonization, the bayou remained a persistent landform until the early 1800s. At the Coles Creek period village, there were more shallow deposits of a historic shell road and cypress bridge. We drew from extensive land ownership history to interpret these features effectively. In order to establish more historically accurate placements of drainage systems at the site, the Mississippi River Commission’s maps from the late 1800s served as a reference. Reading through the family’s letters and general correspondence about the acquiring backswamp lands helped to place these features in both time and place. In 1850, the U. S. Government passed the Swamp Lands Act, which enabled the purchase of backswamp lands ( as determined by the Secretary of the Interior ) for drainage and agricultural production. In this way, the landowner could buy the land behind his property and turn over the new fields as enslaved laborers cut fresh cypress and hardwoods for property improvements and fuelwood for the sugarhouse. As such, the bayou was likely still active until the 1850s.

We began changing the way we survey these areas as a result of tracing this bayou between several locations in nearby sugarcane fields. We have discovered additional earlier pre-Colonial and Pre-Contact European sites where some might have once advocated for greater spacing between shovel testing approaches on a traditional archaeological survey. These areas are further complicated by the increased development and increased scrutiny of the long-term effects of environmental change and erosion. One perspective on how we attempt to better understand the history of land in these dynamic environments is the constant fluctuation in these dynamic environments.