Changing Courses for Archaeology in Louisiana’s Bayous

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

Bayous are subject to constant change over the long course of history. The rate of change today is unprecedented. As a result, many archaeologists working in southern Louisiana are developing unique approaches to understand the changing environments and their heritage at risk.

Mentions of Louisiana’s swamps and bayous conjure images of a shifting landscape of wild or bucolic imagery. These images often include scenery where Spanish moss hangs over still water while cypress knees chart clear paths for flat boats to cross. One could imagine the diversity of bird calls filling the air while a sea of lush green forests directs one’s path through a seemingly thick and remote wood.

Set back from the Mississippi River’s modern levee system, agricultural fields become a sea of sugarcane set ahead of a thick backdrop of swamps and bayous. Nevertheless, this seemingly remote landscape is a significant cultural resource. While difficult to navigate now, these waterways provided the same pathways where enslaved individuals formed networks towards freedom during times of antebellum oppression, and others including, but not limited to: Isleños, Acadians, and the ancestors to modern Chitimacha, Coushatta, and Houma (to name a few) who used these waterways to transport items and ideas. Archaeologically speaking, probability modeling relies upon data that, not to the researcher’s fault, may not consider historical environments, land use, and other environmental data that may not necessarily appear within historic cartographic sources. The core issue with researching settlements in these environments is that archaeologists could assume relative stability over time. The course of the bayou is not static. In the face of a changing climate suffering from significant losses to land and heritage, we are left with opportunities to develop creative ways to identify this heritage at risk. One such methodology we can employ is shallow geophysical surveying.

Figure 1. Sugarhouse ruins in the backswamp, Ascension Parish. Photograph by Steven Filoromo, July 2022.

Figure 1. Sugarhouse ruins in the backswamp, Ascension Parish. Photograph by Steven Filoromo, July 2022.

Within southern Louisiana, my colleagues and I are fortunate to have had opportunities to employ magnetometry across various sites. Magnetometry is a unique form of shallow geophysical surveying. The data in total across a site or landscape create a palimpsest of natural and cultural features, condensing approximately two meters of stratigraphy within an atemporal two-dimensional image. Things like relict streams, landscape modifications, hearths, architecture, and more can appear. While those distinct cultural features are generally the target of archaeological research, locations of relict landforms such as ancient bayous or relict streams (coulees in Acadiana) are also critical to understanding changes in the landscape. The appearance of these features within magnetic data depends on mixed variables. In a basic sense, the magnetic gradient of sediment layers ranges depending on their residual (remanent) magnetization from the acquisition from an external field and their ability to be magnetized from an applied field (magnetic susceptibility). These differences in the gradient are significant as relict channels have different remanent magnetization, thus appearing in contrast to the surrounding environmental and cultural features (e.g., Stele et al. 2020; Heller & Evans 2002).

During recent archaeological projects in Iberville Parish, where we were determining the integrity of a sugarhouse site (Phase II testing) and a full-scale excavation of a large Coles Creek village (Phase III data recovery), we conducted a magnetometry survey before any new ground disturbance. We covered approximately 3.3 acres for the sugarhouse, and at the Coles Creek period village, we surveyed 7.33 acres. Fortunately, both sites sit within a similar location set back from the levee, along with the exact change in elevation within the adjacent sugarcane fields. For the sugarhouse, there were very few indications of any distinct cultural features; whereas, at the village, there were numerous anomalies related to structures, a historic road, and several ditches. Notable between both datasets were subtle contrasts in low magnitude (between 2 and -2 nT, or nanoTeslas) magnetic variations across both areas. The general trend between both locations was that an area of low magnitude negative magnetic variation defined the boundary between the fields and bayous. The difference between the two locations was that the interior of the former bayou at the village contained more prominent, subtle anomalies with positive magnetic variation.

Figure 2. Magnetometry data at the village and sugarhouse.
Figure 2. Magnetometry data at the village and sugarhouse.

During the excavation of the sugarhouse, a series of mechanically excavated trenches generally confirmed the location of the former bayou channel. Soil textures and colors were noticeably different, whereas bayou soils have more clay and darker colors. We observed a similar trend in the village. Given the size and nature of investigations, we could delineate the bayou as it crosscut the village fully. The areas of more positive magnetism within the bayou comprised significant quantities of terminal Coles Creek (ca. AD 1200) ceramics. Given the nature of fired ceramic production and the quantities of these materials, the areas of higher magnetism within the bayou are unsurprising. During the excavation of the village, it became clear the significance of this waterway to the layout of the village. Massive pits and several hearths marked the center of a distinct shared communal area with sheet middens surrounding several smaller neighborhoods focused on the sides of the former bayou.

Figure 3. Portion of excavation results in a focused area at the village.

Figure 3. Portion of excavation results in a focused area at the village.

While the location of the bayou next to the village provides insight into the use of the area before attempts of French colonization, the bayou was a persistent landform even through the early 1800s. A historic shell road and cypress bridge were in more shallow deposits at the Coles Creek period village. To effectively interpret the timing of these features, we drew from extensive land ownership history—maps from the Mississippi River Commission in the late 1800s provided a baseline for determining more historic placements of drainage systems at the site. Sifting through the family’s letters, more general correspondence discussing the acquisition of backswamp lands helped 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. Thus, the landowner could purchase the land behind his property and turn new fields over 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.

As a result of tracing this bayou between several sites within adjacent sugarcane fields, we began to alter our approaches to surveying these areas. Where some once might have advocated for greater spacing between shovel testing approaches on a traditional archaeological survey, we have located additional earlier pre-Contact and Colonial European sites. Development across these areas and the greater birds-eye view of the long-term impacts of erosion and environmental change add additional layers for identifying and protecting heritage at risk. The constant fluctuation in these dynamic environments provides one perspective on how we attempt to better understand the history of land in these environments.

Historic Shipwrecks of The Red Sea

By Alicia Johnson, Graduate Researcher, Alexandria Centre For Maritime Archaeology & Underwater Cultural Heritage

While scouring the depths of the Red Sea in 1955, Jacques Cousteau, a famed explorer, discovered the famous Thistlegorm, a British merchant vessel submerged off the Southern tip of the Sinai. The extensive documentation and international media coverage of Cousteau’s discovery spurred significant public interest in maritime exploration and launched the shipwreck’s reputation as a remarkable dive site. It is estimated that Thistlegorm, a World War Two British warship sunk by Luftwaffe forces in 1941, brings in 5 million Euros of revenue a year and attracts thousands of visitors each year to the Red Sea of Egypt. Over time, as diving gained popularity, the wreck has become a large attraction for international divers and was recently awarded the #2 Best Shipwreck dive by PADI this year. 

Thistlegorm photogrammetric model by Simon Brown.

Throughout history, ships have been anthropomorphized and evolved alongside mankind, often taking on a life of their own; even in death, a ship’s demise is as dramatic as that of its flesh and bone crew. Akin to its makers, a ship’s death can be followed by its resurrection via explorers, filmmakers, musicians, story tellers, divers, maritime archaeologists, and museums. In short, a ship’s life does not cease just because it slips beneath the seas; instead, a shipwreck metamorphosizes into a valuable time capsule and an irreplaceable addition to humanity’s shared maritime cultural heritage. These historic shipwrecks can provide information benefitting academic research, stories, myths, and media which delight the public, sights of attraction for tourism and sports divers, and avenues of commerce, revenue, and employment which stimulate the local economy.

Protection of Historical Shipwrecks

Prior to the advent of recreational SCUBA diving, wrecks remained largely inaccessible to people and preserved by the anoxic underwater environment; however, with the popularity of recreational diving, shipwrecks have become SCUBA tourism destinations. Whereas deep sea wrecks remain largely unreachable by recreational SCUBA divers, shallow water wrecks have become an attraction for divers, a target for looters and salvers, and are at risk of decomposition and destruction.

Classified as Underwater Cultural Heritage (UCH) by UNESCO’s 2001 Convention on the Protection of the Underwater Cultural Heritage, historic shipwrecks (<100 years of age) are acknowledged to be “an integral part of the cultural heritage of humanity and a particularly important element in the history of peoples, nations, and their relations with each other concerning their common heritage.” As protection is afforded to shipwrecks older than 100 years, WWII ships, such as Thistlegorm, are excluded from protective legislative, leaving them in a purgatorial status of increased degradation.

Popular historic Wreck Dives of the World

Many diving destinations are found in developing countries which offer travelers a pleasing and budget friendly vacation. For example, several premiere wreck dives, such as Thistlegorm (Egypt), Basuanga Bay (Philippines), and Liberty (Indonesia) are historic sites which attract many visitors a year and stimulate the local economy. The positive influx of tourism benefits the local community and provides employment opportunities to the local population.  Dive tourism creates a need for hotels, marinas, boats, dive centers, restaurants, retail and so forth.  During the last half century, the Blue Economy has prospered and brings high value tourists to developing countries.

However, many of these historic shipwreck sites, such as the Thistlegorm in Egypt, are at-risk heritage sites and face difficulties with archaeological efforts to excavate, document, and manage the site. Effective heritage management can be hampered by domestic political issues, insufficient resources, limited funding, and a shortage of local specialists; mismanagement, or lack thereof, can lead to a lack of oversight, loss of archaeological integrity, unsustainable number of visitors, and little public outreach—all of which can be harmful to a site’s preservation and diminish cultural appreciation. Without effective management these sites deteriorate at a faster pace and face the risk of being irreparably damaged or lost.  

History of the Thistlegorm

While the Thistlegorm site has become a flagship of Scuba and Egyptian tourism, the wreck is, more importantly, a grave and a reminder of the sacrifices made during WWII’s North African theater. Lost during WWII, Thistlegorm was an armed commercial freighter ship carrying a cargo of vehicles, aircraft spares, and ammunition, and sunk by a Nazi Luftwaffe air raid in 1941. Operating with a crew of 42, the 131m Thistlegorm was an Albyn Line merchant refitted with 4in high angle anti-aircraft gun, 12pdr low angle gun for surface targets, and machine guns.

Thistlegorm faces unavoidable threats such as weather and currents; however, our human impact on the site is manageable. Ongoing Maritime Archaeological Projects, such as the Wrecks at Risk and Project Thistlegorm, are working to document the site and have created a photogrammetric model of the wreck, similar to the recent Titanic scans. Simon Brown has also created an orthomosaic of the wreck. In the future, efforts are being made to create a more efficient mooring system and to have the site recognized as a UNESCO Cultural Heritage Site; but thus far, the shipwreck is open year-round to copious numbers of divers and a destination offered by many dive companies from the Sinai and Hurghada.

If you can visit Egypt…and want to dive Thistlegorm

be sure to book a live aboard safari out of Sharm el Sheikh or Hurghada. Egypt has some of the world’s most beautiful and affordable diving and consistently ranks as one of PADI’s top countries to dive. Enhanced by historical shipwrecks, such as Thistlegorm and Carnatic, the Red Sea is characterized by the colorful aquarium like reefs teeming with sea goldies. Diving the Red Sea grants visitors an immersive and interactive experience with marine biodiversity and a chance to explore the rich history of the Indo-European trade and military history.  A visit to the underwater museum of Thistlegorm will be unlike any other trip you have ever had, and you’ll swim away with travel photographs to last a lifetime. If you would like to know more about the Thistlegorm, please check out the book: Diving the Thistlegorm: The Ultimate Guide to a World War II Shipwreck.

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Climate Stories!! How HARC has adapted Storytelling Methods to Share Archaeological Sites at Risk from Changing Climates

By Allyson Ropp, Ph.D. Candidate, East Carolina University

Think back to your favorite story. What made it so exciting? Was it the characters? Was it the conflict or problem that the main characters needed to solve? Or was it how the characters ended up solving the problem? Maybe it was all three!

What all good stories have in common is a beginning, a middle, and an end – each setting up an important part of the story that brings you into the action. The beginning is the setup. It provides the exposition of the story, introducing us to the main characters and their world. The middle presents a problem, conflict, or situation the characters must address. This could be a wrecked ship on a voyage home or the loss of a parent, but regardless of what it is, it provides a problem for the characters. The end wraps up the story and allows the characters to solve or achieve a resolution of the problem. While the main character may have experienced a shipwreck on the way home, she was able to alert a passing ship and therefore made it home in time for her sister’s wedding. These three components reflect the “ABT” framework of storytelling.

Graphic showing narrative arc for climate stories

Figure 1. Story Arc (Ropp, 2023)

The “ABT” framework, or the “And, But, Therefore” framework, has been used in storytelling for years, even if it was known by another name, such as the Hero’s Journey (Olson 2018:6; The Publication Plan 2020). Before this framework, scientists, including archaeologists, fell into the style of storytelling that was “And, And, And,” where all information was presented but did not provide a narrative for the work. Olson saw the need for more effective science communication; therefore, he brought storytelling to science through the ABT Framework (For more information on the ABT Framework, check out his books and TedTalk).

This framework has been utilized by the SHA Heritage at Risk Committee (HARC), drawing on inspiration from Marcy Rockman and Jakob Maase’s article “Every place has a climate story: finding and sharing climate change stories with cultural heritage” (2017). This article champions the use of the ABT Framework as a way to tell stories integrating climate change and cultural heritage, including tangible archaeological remains.

Since its inception in 2017, HARC has used different platforms to tell the climate stories of cultural heritage. One method is the Heritage at Risk – Climate Stories Pop-Up Exhibit. The pop-up exhibit allows archaeologists to share transformational stories of heritage at risk from our changing climate. As archaeologists worldwide are concerned about the multitudes of impacts that climate change can have on tangible and intangible heritage, the exhibit offers a space for archaeologists to learn from one another and share it with the public. This exhibit features a global collection of case studies highlighting the issue and looking for sustainable solutions. All the case studies within the exhibit utilize the ABT Framework to lay out the narrative of the impacted site, the impacts to the site, and solutions undertaken by professional and avocational archaeologists to combat the impacts.

Panel from Heritage at Risk Committee pop-up exhibit on sites at risk of climate impact

Figure 2. Pop-Up Exhibit Title Panel and Case Studies (Grinnan 2020)

In 2022, the physical pop-up exhibition expanded to include a digital component. To reach a broader audience, the pop-up exhibit became an ESRI StoryMap. This StoryMap took the contents of the physical display, expanded on the stories of each site, and spatially showed the breadth of climate change impacts, allowing HARC to tell a global story about climate change impacts to cultural heritage.

Title card for the Heritage at Risk Committee Digital StoryMap

Figure 3. Title card for the HARC Digital StoryMap (Wholey 2019; photo credit South Carolina DNR).

The current exhibits include case studies from North America and Europe. These case studies cover sites dating from the Archaic period to the mid-twentieth century, with site types ranging from shell middens and shipwrecks to plantations and industrial structures. These case studies provide unique context-dependent climate stories and cross-continent comparative examples of similar climate impacts and management strategies. For example, coastal erosion is a common thread in many current climate stories. This erosion impacts shell middens in Maine and Florida, heritage resources and modern-day communities in Alaska, and fishing and industrial sites across the British Isles. While these different sites face a similar threat, the contributions of the contributing partners to this exhibition provide a variety of techniques that can be applied to other sites worldwide. For example, organizations such as the Florida Public Archaeology Network and CHERISH in Ireland and Wales utilize emerging technologies like terrestrial laser-scanning and unmanned aerial vehicle/drone-based photogrammetry to survey sites. Other initiatives, like the Maine Midden Minders, SCAPE in Scotland, and the Society of Black Archaeologists at the Estate Little Princess in St. Croix, leverage community groups to record sites and conduct assessments before, during, and after large-scale erosion events and hurricanes.

Map of current case study locations from StoryMap

Figure 4. Map of current case study locations (Wholey 2019)

Finally, HARC has sponsored several 3-Minute Climate Story panels at the annual SHA conferences. These panels bring together climate stories from around the world. These stories are told using the ABT Framework and Rockman and Maase’s “Every place has a climate story” themes through a video format. To help make cultural heritage research and climate change impacts more accessible for archaeologists and the public, the video allows archaeologists and heritage professionals to tell the story of a site and share the video across different platforms. This year’s 3-Minute Climate Story panel will focus on Rockman and Maase’s first theme – “Change in the Material World.” This theme makes climate change tangible, focusing on how material culture changes and how archaeologists can identify and monitor this change (Rockman and Maase 2017:110).

These storytelling efforts promoted by HARC represent only a small fraction of the sites at risk and the stories that can be told. As heritage sites are facing these impacts across the globe, we want to help you tell the story of a heritage site at risk from climate change. If you are working on a site at risk from our climate crisis, we would love to help share its story and your work in mitigating the effects! Please complete this Google Form to tell us about your site’s story and share it with the larger archaeological community. Are you unsure if your site fits into our exhibition? Want to participate in a future 3-Minute Climate Story session? Email Allyson Ropp at for more information.


Olson, Randy

2018    Don’t Be Such a Scientist: Talking Substance in an Age of Style, 2nd Edition. Island Press, Washington DC.

The Publication Plan

2020    The ABTs of science communication: expert advice from a scientist-turned-filmmaker. The Publication Plan: News for Medical Publication Professionals. Accessed 7 June 202

Rockman, Marcy and Jakob Maase

2017    Every place has a climate story: finding and sharing climate change stories with cultural heritage. In Public Archaeology and Climate Change, Tom Dawson, Courtney Nimura, Elias Lopez-Romero, and Marie-Yvane Daire, editors, pp. 107-114. Oxbow Books, United Kingdom.

Shipworms and Gribbles and Pill Bugs, Oh My!

By Susan B.M. Langley, Maryland State Underwater Archaeologist

2023 celebrates the 35th anniversary of the Maryland Maritime Archaeology Program

In Maryland, April is Archaeology Month and May is Preservation Month, so this is an appropriate time to consider these tiny creatures that pose a large threat to the preservation of submerged archaeological resources. While these marine woodborers have impacted commerce and safety since humanity took to the sea, changes in construction materials of ships and harbor infrastructure, as well as the use of effective but environmentally dubious chemical treatments, greatly reduced their negative effects. There is still a toll; damage to harbor infrastructure by shipworms was estimated at $1 billion USD globally in the early 21st-century (Cobb, 2002) but this still compares favorably to the $500-$900 billion (based on 2009 dollar values) in damage over just two years, 1919-1921, in San Francisco Bay alone (Rayes et al. 2015:488). However, climate change appears to be a factor in the spread and adaptation of these woodborers enabling them to tolerate both fresher and much colder waters and permitting them access to a veritable smorgasbord of historic vessels.

It should be noted that various fungi and bacteria also degrade and rot wood and are the subjects of ongoing studies regarding their effects and the extent to which climate change may be affecting them.  This discussion considers the three main categories of marine woodborers.

Pill Bugs (a.k.a. Roly-Poly, Rollie Pollie, Doodle Bug, Potato Bug, and more) are not insects but terrestrial crustaceans (Figure 1).  Although Armadillidium vulgare is one of the most common, they are so diverse that they are usually referenced by Family; Armadillidiidae.  Although they are crustaceans and breathe through gills they cannot live under water (Reconnect 2023) but live in wet environments like mangroves.  They can damage the latter extensively, which has a bearing on low-lying areas that are coming to rely on mangroves for protection against storms and sea level rise, as well as maritime infrastructure built in these environments.  Because of their larger size compared to the much smaller shipworm and gribble, they were recognized and studied earlier.  They do not eat wood but chew through it to create burrows for shelter and, historically, have had far less impact on ships and harbor structures than the other woodborers. 

Pill bugs

Figure 1. Pill Bugs. ( 2023).

It took longer to differentiate gribbles and shipworm because of their small size and the apparent similarity of the damage they caused, despite the gribble being a crustacean and the shipworm being a mollusk.  Both actually digest the wood as opposed to burrowing through it.  There are more than 50 species of marine isopod in the gribble Family Limnoriidae and many of these bore into plants and grasses as well as wood (Figure 2).  The gribble (Limnoria lignorum) as a threat to vessels was identified in 1799.  These are the smallest of the woodborers and leave tiny entry holes that belie the extent of the internal damage they can cause. On the wreck of the vessel believed to be James Cook’s Endeavour off Rhode Island, Reuban Shipway identified both gribbles eating the exterior of the vessel and shipworms devouring the interior of the hull (Kuta, 2022).  A further concern is that as the wood weakens and breaks, creatures that feed on the woodborers can cause additional damage by rooting for them.  There are not a lot of known predators as long as the piece of wood is intact, but when the wood disintegrates, they are rapidly eaten by fishes, crabs, and other predators. They are vulnerable to protozoan parasites, such as Minchinia teredinis, which can cause extensive mortality (Hillman et al. 1990)” (Smithsonian 2023).  Nelson (1925) also suggests the Warty Comb Jelly, or sea walnut (Mnemiopsis leidyi), a species of tentaculate ctenophore, that is known to be a significant predator of mollusk larvae.  Gribbles appear to be native to western Atlantic coastal waters, but have become established as an invasive species in European and western Asian regions.


Figure 2. Gribbles; image on left is 0.5mm (Encyclopedia of Life 2023).

The most infamous of these “termites of the sea” is the shipworm.  While there are a number of species, often named for the regions where they are found, the eponymous Teredo navalis can represent them all (Figure 3).  It does not look like the bivalve it is, because most of its body is external, taking the form of a worm, with the two shells being reduced to small plates at the head designed to auger through wood.  It has been found in fossil form dating from the Cretaceous period (145-66 MYA) but the earliest evidence of them impacting humanity comes from Egypt.  Hull planks from excavations show Teredo damage and efforts to address this through use of thicker planks on oceangoing watercraft versus river vessels, additional sacrificial wood at joints and seams, choices of denser, more finely grained woods like cedar (Cedrus libani) and Nile Acacia (Acacia nilotica), and the application of a coating of pine tar to the hulls (Rayes et al. 2015, Ksenija Borojevic et al. 2010, Polzer 2011, Ward and Zazzaro 2009). So it continued through time, with various coatings being applied; from Pliny the Elder’s reference to zopissa (bee’s wax and resin) to substances like tar, brimstone (sulphur), or arsenic. Then there were efforts to sheath the hulls from additional layers of sacrificial wood to lead sheathing from Greek and Roman times through similar endeavors by Spain and England in the 14th and 15th centuries.  The tacks holding the lead sheathing to the hull tended to corrode and the metal then fell off exposing the wood. Japanese boatbuilders even scorched the exterior of the hulls to deter the borers (Thunberg 1796).  Again, there was an effort to find Teredo-resistant wood species.  Two that offered promise were Cuban cedar (Cedrela odorata) and the Cabopa tree (Mitragyna stipulosa) from Cacheu; a region of what is now Guinea-Bissau, and since Spain built about a third of its Navy in Cuba in the 18th century this connection demonstrates the merit of studying placement of shipyards in proximity to where teredo-resistant timbers grew (Aderinto 2007, McNeill 2004). Copper sheathing had its first success when applied to the Royal Navy vessel Alarm in 1761 and became widespread thereafter whenever a builder could afford it.  The late 19th and 20th centuries saw a return to applied coatings, but of metallic anti-fouling paints of significant toxicity including mercury, and chrome copper arsenate, as well as somewhat less toxic turpentine and borax, although these are still undesirable (Paalvast and van der Velde2011) and most were outlawed by the late 20th-century.  The widespread use of ferro-concrete in harbor structures after 1900 also aided in reducing damage.  In the 20th-century, increased Teredo activity was experienced by urban and developed areas after steps were implemented to reduce the level of pollution in the waters.  New York City, after the Clean Water Act of 1972, saw improved water quality but also extensive woodborer damage between 1995-1997 such that a 21-meter(23-yard) section of a wharf dropped into the East River, and a 6-meter (6.6-yard) section fell from the Brooklyn pier (Rayes et al. 2015:488, Paalvast and van der Velde 2011:119). Similar situations have occurred in Maine in 2000, on the Rhine River and in the port of Rotterdam (Cobb 2002), and are currently occurring in Venice (Figure 4).  Ironically, pollution had been protecting these and, by extension, submerged heritage resources.

Teredo navalis

Figure 3. Teredo navalis (David Fickling 2020).


Teredo damage to dock

Figure 4. Teredo damage to a wharf in Venice (Langley 2022).

The origins of these marine woodborers are not clear since they were not studied until they became a threat.  Pill Bugs are believed to have originated in southern Europe and/or northern Africa (Higgins 2023).  Gribbles, as previously, noted, are native to the western Atlantic but Teredo are thought to have originated in the Pacific and Indian Oceans (WreckProtect 2023).  As they were in Egypt’s harbors so early, it may speak to their introduction to the Mediterranean via vessels brought overland from Egypt’s Red Sea/Indian Ocean trading and fishing expeditions and, like most invasives, they spread rapidly.  The introduction and widespread proliferation of shipworm outside of the Mediterranean correlates with the expansion of European maritime trade into the Indian Ocean and subsequently to the Caribbean and beyond.  Although they are considered warm water species, they adapted sufficiently rapidly to Atlantic waters to force the beaching of the vessels Capitana and Santiago during Columbus’s fourth voyage, in 1503.  In 1731, they caused extensive damage to the wooden seawalls holding back the ocean from the reclaimed lands of The Netherlands and kept the citizens living in fear of a disastrous flood for the two years it took to repair and reinforce the seawalls.  In an 1873 publication about the laying of communications cables, Sir James Anderson, complained about them boring through the core of the cable in shallow water, and devouring the hemp covering in a few months and inhabiting the interior gutta-percha covering at depths of 2.2 km (1.37 mi) and said that the only protection was burying the cables but noting that they could not be relied upon to stay buried (Anderson 1873).

Conventional wisdom has been that shipworm requires warm salty water to survive and this seemed to hold for the Mediterranean where ship remains only survived if they were buried or covered by cargo like amphorae.  Cold, more brackish, waters preserved vessels beautifully, as is evident in the myriad vessels in the Baltic Sea.  However, more recently it has become apparent that climate change is increasing salinity, as well as warming the waters, of the Baltic (WreckProtect) and, also, many European Rivers are experiencing a migration of salinity upstream (Paalvat and van der Velde 2011:120).  Species of Teredo are also adapting to tolerate much colder and fresher waters.   This has been reported by WreckProtect during a two-year project funded by the European Union between 2009-2011.  Also, a log was recovered by a research vessel from 250 m (273 yards) depth and only 1100 km (683 miles) from the North Pole and with a water temperature of -1.8°C (28.8°F) that was riddled with a living multi-generational colony of Teredo (Kintisch 2016).

The Chesapeake Bay covers an area of 4,479 square miles in both Maryland and Virginia, with five major rivers in Maryland and a further 111 square miles of State coastal waters.  Certainly, climate change is evident and being addressed through the State’s Climate Change Program and its sub-programs. However, Teredo and another woodborer present in the Bay, Bankia Gouldi L., are not considered in these.  Most of the studies of shipworm in Maryland date from the early 1950s (Maryland Tidewater News 1951, Schelema and Truitt 1956). The average depth of the Bay, outside of the 80-foot deep shipping channel, is about 45 feet, which means it is heating very rapidly; 1°C (1.8°F) over the last 30 years (NOAA 2023).  This is already being expressed in the proliferation of the flesh-eating bacteria Vibrio vulnificus (NOAA 2022).  At present, submerged historic resources in Baltimore Harbor may be benefitting from the double-edged sword of the extant pollutants, but the more than 5000 wrecks in Maryland waters are increasingly at risk.  Until more studies are undertaken, the best resources available for managing the maritime resources are the detailed manuals produced by WreckProtect which offer guidelines for protecting submerged wooden cultural sites (2011a) and guidelines for predicting shipworm damage (2011b).  Although the latter focuses on the Baltic, it is relatively recent and can be adapted.  While it will take time for the 100 WWI vessels in the Mallows Bay-Potomac River National Marine Sanctuary to be under direct threat from shipworm, it may be sooner than anticipated.  It would be a sad irony for ships that faced all the challenges of seafaring with storms, reefs, and battles, to be lost to a 15mm (0.5 inch) mollusk.


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Paalvast, Peter and Gerard van der Velde. 2011. “New Threats of an old enemy: The distribution of the shipworm Teredo navalis L. (Bivalvia: Teredinidae) related to climate change in the Port of Rotterdam area, The Netherlands,” Marine Pollution Bulletin 62(2011):1822-1829.

Pest World. 2023. Image of Pill Bugs. Accessed May 14, 2023:

Polzer, Mark. 2011. “Early Shipbuilding in the Eastern Mediterranean,” A. Catsambis, B. Ford, and D. Hamilton (eds.) The Oxford Handbook of Maritime Archaeology. Oxford University Press: NY. Pp. 349-378.

Rayes, Courtney, James Beattie, and Ian Duggan. 2015. “Boring Through History: An Environmental History of the Extent, Impact and Management of Marine Woodborers in a Global and Local Context, 500BCE to 1930s CE,” Environment and History 21(4):477-512.

Reconnect. Reconnect with Nature. The Nature Foundation of Will County, Illinois. Accessed May 14 2023.

Scheltma, Rudolf and R.V. Truitt. 1956. “The Shipworm Teredo navalis in Maryland Coastal Waters,” Ecology 37(4):841-843.

Smithsonian Nemesis. Marine Invasions Lab. “Teredo navalis.” Accessed May 14, 2023:

Ward, Cheryl and Chiara Zazzaro. 2009. “Evidence for Pharaonic Seagoing Ships at Mersa/Wadi Gawasis, Egypt,” The International Journal of Nautical Archaeology 39:27-43.

World Economic Forum. 2018. Image of Gribbles.

WreckProtect. 2023. Home Page. Accessed: May 9, 2023.

2011a. “Guidelines for the Protection of Submerged Wooden Cultural Heritage,” Accessed May 14, 2023.

2011b. “Guidelines for Predicting Decay by Shipworm in the Baltic Sea,” Accessed May 14, 2023.

Using Machine Learning and Spatial Statistics to Measure the Geometric Structure of Archaeological Spaces

By Lindsey Cochran, Assistant Professor, East Tennessee State University; Grant Snitker, Director of the Cultural Resource Sciences and Fire Lab, New Mexico Consortium

An urgent question for archaeologists as we race to react to the climate crisis is: what are we losing? The biased nature of the collective archaeological dataset presents an unequal assessment of heritage at risk. As we know, today’s cultural landscape boundaries are different than those in the past. The majority of known cultural heritage sites are driven by cultural resource management and compliance, meaning known sites are often located near roadways, pipelines, reservoirs, and military installations. We propose that in addition to assessing which cultural heritage sites are at risk, archaeologists should also work to understand how under-investigated landscapes contribute to how we evaluate landscapes most likely to change enough to threaten, damage, or destroy our ability to interpret the past for future generations.

Figure 1. An optimized hot spot analysis of the relative densities of known archaeological sites in Georgia, USA. This map shows statistically significant hot and cold spots of identified archaeological sites using the Getis-Ord Gi* statistic. The red hotspot is Fort Stewart Army Base where NHPA catalyzed a fuller survey of cultural resources. Cells with no value indicate an absence of documented archaeology sites. Cells represent density of known sites within that hexagon, not site locations.

Within those known sites, archaeologists most often only excavate a small fraction of an area where people may have left cultural materials behind. Of those, only a few certain materials persist over time and are available for recovery. So when we ask “which non-renewable cultural heritage resources are we losing” because the climate emergency, the answer is that we’re not really sure.  Rather than using only the things people left behind, we propose to leverage the bias inherent in archaeology: non-uniform excavation strategies within and between sites, and differential preservation of material culture, by using historical maps to supplement the places in-between excavations.

Historical maps allow archaeologists to gain a greater understanding of how past people viewed and navigated the world around them. However, these documents were created by people and for a purpose, meaning that historical maps depicting the same place at the same time, but created by different people, can tell dramatically different stories. Despite an element of inherent bias, historical maps are a tether to, at minimum, a cultural understanding a landscape and the potential presence of previously undocumented archaeological resources.

Here, we propose to leverage our biases: What could be known that we haven’t thought to investigate (yet)? For example, on the coast of Georgia, USA, can we use historical maps to estimate the location of resources that have little or no documentation, specifically Irish landholdings, farmsteads, small plantations? What elements of the landscape influence the presence or absence of a resource that has not yet been archaeologically documented?

We propose that historical documents, specifically historical maps, can be used as input data to investigate where significant archaeological sites may be located, the landscapes they occupy, and what future risks form climate change they might experience.  

Then, machine learning algorithms can be used to identify places on the landscape where there may be very significant cultural heritage resources that we are unaware of. These locations can then be cross-referenced with NOAA models of climate change or an archaeological triage assessment of those models to identify which potentially significant areas should be first surveyed prior to probable destruction.

Our case study is from a coastal t-sheet from Sapelo Island, Georgia, USA created by H.S. DuVal in 1857 and reported to his superintendent, A.W. Evans in the same year. Alone, these documents contain useful information about how the landscape has changed over the last 200+ years. One such example is a simple note: “A new channel developed leading into Sapelo sound, Ga., three-quarters of a mile southward, and better than the one in use, 1860” (1863:78). The reconnaissance map maker is potentially indicating the new use of the Cabretta inlet, which is now undergoing rapid change. The report of DuVal to Evans also contains useful information about the cultural context of the survey—plantation owner Thomas Spalding hosted DuVal and encouraged him to place one of his five transect lines through the Gullah-Geechee Behavior Settlement.

Proof of Concept Methodological Steps

In this proof-of-concept study, we georectify and vectorize elements of the historical landscape that were noted by the reconnaissance surveyor that could have influenced the presence or absence of an historical site. Those elements are then used as testing and training samples to determine if there are relatively standard cultural and environmental landscape attributes that can be used to determine is likelihood of the presence or absence of a plantation site on the Georgia coast.

We have established four basic steps to this machine-learning methods for identifying plantation sites using datasets derived from historical maps:

1. Georectify the historic map to place it into real space.

Figure 2. Location of Sapelo Island, Georgia with the DuVal (1857) reconnaissance map georectified to the modern landscape.

2. Digitize model inputs within the landscape using archaeological experiences like pedestrian surveys and Phase I/II surveys, historical sources, and expert inputs to create landscape variables. In this case, we used vector inputs within the computational extent of the project area, vegetated areas, potentially arable land, proximity to structures, proximity to roads, and proximity to other cultural features (Figure 3).

Figure 3. Binary and continuous variables for classification into the machine learning algorithm.

3. Create a training set for the random forest classifier. A random forest classifier is a supervised machine learning algorithm that essentially grows multiple uncorrelated decision trees (Figure 4). After training samples are run through the many decision trees, results are aggregated into a majority class. The benefits of a random forest classifier are that the estimates fit a number of decision trees and sub-samples of the data to improve accuracy of the model and reduce over-fitting the training samples (Figure 5).

Figure 4. Random forest classifier in machine learning. (Image from

Figure 5. Testing versus training inputs, closeup of the Spalding Sugar Plantation, Sapelo Island, Georgia, USA

4. Classify the entire landscape based on the training results (Figure 6).

Figure 6. Results of the random forest classifier. Yellow indicates a high probability of the presence of an element of a plantation site, whereas blue indicates a high probability of the absence of a similar site.

Overall, the model performs well to identify already known and potential plantation sites and activity areas within our study landscape. The model processing and production took place in R, which means that the processing steps and code is freely available, shareable, adaptable, and replicable. Finally, we are working to automate the digitization and vectorization process. However, because the historical map-makers are human, each map contains elements that need to be interpreted by a human. A computer might interpret the ink blot highlighted in Figure 7 as a structure, rather than an accidental mark made by the mapmaker.  While this process was time intensive and limited to what is observed in each map, the next steps of this project are to expand our case studies beyond Georgia’s barrier islands and to the more inland sites that have been the subject of fewer or no studies at all.

Figure 7. A red circle is around a selection of archaeologically verified slave cabin, whereas the blue squares are around ink-blots pretending to be archaeologically significant.


What makes archaeology so interesting to us is that the nature of archaeology prohibits a complete understanding of our data. The puzzle will always remain a puzzle, but ideally with fewer missing pieces as research projects continue. Despite the ever-incomplete nature of our discipline, historical archaeologists have a unique relationship with a dataset uncommonly used when researching heritage at risk sites.

We propose the development of a carefully interpreted machine learning approach, such as the one presented here, for using existing datasets in a new way to address a developing crisis. A create reinterpretation of existing data may facilitate our disciplinary creation of endangered sites lists that include probabilities of an area to contain as-of-yet undocumented resources. We suggest that a part of our response to the climate emergency includes a conversation about prioritization: should we direct more resources to preserving sites that what we already know about or to identify what we could know but may never have the chance to know.


Bache, A.D.

1864     Report of the Superintendent of the Coast Survey, Showing the Progress of the Survey during the Year 1863. Washington Government Printing Office. Washington, D.C. Accessed 6 Feb 2023. <>

DuVal, H. S.

1857 Topographical Reconnaissance of Sapelo Island, Georgia. United States Coastal Survey, A. D. Bache, Superintendent. Atlanta: Surveyor General Department, Office of the Georgia Secretary of State.

Evans, A.W.

1857 Letter of the Secretary of the Treasury, Communicating the Report of the Superintendent of the Coast Survey, Showing the Progress of That Work During the Year Ending November 1, 1857. Appendix No. 39: 347-377.  < rescue/cgs/001_pdf/CSC-0006.PDF>.

Drowning in the Drink: Climate Change and the Threat to Coastal Moonshine Still Sites

By Katherine G. Parker, Doctoral candidate, Department of Anthropology, University of Tennessee, Knoxville

When first I met with Bob Morgan, then the Heritage Program Manager for Francis Marion National Forest (FMNF) in South Carolina, in 2019 to discuss my interest in researching families involved in moonshining on land that the Forest Service now owned, he warned me that there wouldn’t be much left. The Bureau of Forestry, which had preceded the US Forest Service, had bulldozed every remnant of human activity on the landscape that they could find when they acquired the land from declining timber companies in the mid-twentieth century. Yet despite the Bureau’s best efforts to scrub the forest clean of thousands of years of the past (and fortunately for this project), dozens of seemingly innocuous piles of metal are still crouched along the banks of streams that are too small to be found on most maps, littered across a stretch of the forest near Hell-Hole Swamp (Figure 1).

Figure 1. View of a typical moonshine still site on the Francis Marion National Forest in Berkeley County, South Carolina.

Given the swampy, low-lying nature of the setting where moonshine stills are often found, it is unsurprising that these sites evaded the mechanical sweeps that cleared away other anthropogenic traces. Even for many archaeologists today, these sites continue to be missed, overlooked, or written off as not worth the effort—and admittedly, the residual collection of rusting barrels along the murky waters of Cane Gully Branch are easily dismissed. At first glance, these sites do not immediately evoke the sense of importance or industry that they once commanded as the core production center for Al Capone’s Southern moonshining capital (The Charleston News and Courier 1972; Miles 2015; Fleming Smith 2020; McCray 2021). Of even greater concern is that, because of the very environmental situations that allowed these sites to evade detection from law enforcement and federal machinery, these archaeological resources now face an even greater threat: climate change.

Documenting Moonshine in the South Carolina Lowcountry

The FMNF Still Sites project began in 2019 to identify, document, and interpret the extent of moonshining in this portion of the Lowcountry. In the years since, the project has identified several additional moonshine still sites in the vicinity of Hell Hole Swamp, conducted test unit excavations at two of them, and begun developing a series of identification criteria and recommendations to aid archaeologists who encounter still sites on routine surveys. One of the challenges faced by our team as we’ve worked to comb the FMNF for new still sites has been our ability to conduct delineations when these sites are actively flooded (Figure 2). The degree of flooding varies widely at these still sites depending on the time of year and on climatic events that force overflow from higher order river drainages into the intermittent stream channels that moonshiners historically favored. During our November 2020 survey, for example, we were forced to postpone delineations and subsurface testing at two sites that were flooded with 6-14 inches of water deposited by Hurricane Eta (by then a tropical storm; Figure 3). According to NOAA, November 2020 proved to be a record-breaking hurricane season for the Atlantic with 30 named storms—the largest count on record since 2005 (NOAA National Centers for Environmental Information 2020).

Figure 2. Archaeologist Katherine Parker documents one of the barrels from a partially flooded moonshine still site on the Francis Marion National Forest.

Figure 3. Archaeologists Kiersten Weber (background, left) and Jordan Schaefer (right) measure site boundaries at a flooded still site during the November 2020 survey after Tropical Storm Eta.

Given that material culture remains that we find at still sites are primarily metal, the frequent wet-dry flooding cycles post a particularly high risk for site loss (Figure 4). The lack of stable environmental conditions exacerbate the oxidation process that degrades these metal artifacts, which in turn drastically accelerates the rate at which the metal breaks down. Because most moonshine stills are identified by the presence of above-ground debris, the most obvious of which are metal barrels and buckets, the loss of these visible markers means that future stills in coastal settings may never be recorded.

Figure 4. Cyclical flooding episodes from climatic events like Tropical Storm Eta threaten the stability of metal artifacts, such as the barrel shown here, on coastal moonshine still sites. 

The Importance of Coastal Moonshine

Moonshine has long been a popular subject for the public, as indicated by the wide range of movies, reality television shows, culture icons such as Gator McKlusky, Popcorn Sutton, and Tickle, and the growing heritage tourism industry centered around Southern moonshining. However, these depictions have shaped our view of who makes moonshine and where; when we think about moonshining, we often think of rural mountain hollers, of wily men with long beards and overalls (or slick suits and fast cars). Rarely do we think about the fact that moonshine was made everywhere, by individuals with different racial, class, and gender identities—spanning centuries of American history rather than the mere 13 years of national Prohibition and intervening decades since. Stories about individuals like Nathan “Nearest” Green, a formerly enslaved man and moonshiner from Lynchburg, Tennessee who taught Jack Daniels the charcoal filtration method that defines Tennessee whiskey today (Risen 2016; Weaver 2019; Uncle Nearest, Inc. 2022), highlight the gaps in what we think we know about moonshining in the past.

As archaeological sites, still sites present the opportunity to better understand divergent histories of moonshining beyond well-trod hillbilly stereotypes—but only if they last long enough for archaeologists to find them.

Interested in learning more about the archaeology of moonshining in the South Carolina Lowcountry? Hear more during the North American Heritage at Risk (NAHAR) virtual lecture on Friday, June 9th, 2023 at 9 am EST.



Fleming Smith, Rachel

2020    SC’s Moonshine Culture and Its Long, Bullet-Riddled History. The Post and Courier January 10, Online Edition edition.   

McCray, Shamira

2021    Booze for Al Capone: Archaeologists Study SC Illegal Moonshine Sites near Charleston. The Post and Courier February 18, Online Edition edition. 

Miles, Suzannah

2015    Moonshine Over Hell Hole Swamp. Charleston Magazine December.     

NOAA National Centers for Environmental Information

2020    Monthly Tropical Cyclones Report for November 2020. Electronic Document. December.  

Risen, Clay

2016    Jack Daniel’s Embraces a Hidden Ingredient: Help From a Slave. New York Times June 25.         

The Charleston News and Courier

1972    Hell Hole Swamp Festival Scheduled for Jamestown. The Charleston News and Courier April 23.          

Uncle Nearest, Inc.

2022    Our History. Electronic Document. Uncle Nearest Premium Whiskey.  

Weaver, Fawn

2019    The Story of Nearest Green. Short Film. The Nearest Green Foundation.

Historical Archaeology and the New Political Landscape in 2023

By Terry Klein, Executive Director, SRI Foundation

The new year brings a news political reality to Washington, D.C. The most significant political change from last year is the Republican takeover of the U.S. House of Representatives. While the Republican majority is narrow, it gives Speaker Kevin McCarthy (R-CA) the authority to decide which bills receive votes in the chamber. Likewise, the new Republican chairs of the House committees will determine which bills get hearings and votes in committee.

House Republican leaders have pledged to use their leadership roles to convene hearings to examine the Biden administration’s record and to build support for their legislative proposals. Expect to see the House Republicans sharply question Department of Interior officials on Biden administration energy policies during televised hearings.

Speaker McCarthy will likely pass many bills that are doomed in the Democratic-controlled Senate. These “messaging bills” are opportunities for House Republicans to demonstrate their policy priorities and signal to their voters what they value. However, it is widely understood that Senate Majority Leader Schumer will not bring many of these largely partisan bills up for a vote in the Senate, so such legislation has no viable path to enactment. To have a real chance of passage, a bill must get significant buy-in from House Republicans, Senate Democrats, and secure 60 votes in the Senate.

One possibility for bipartisan agreement is a bill to streamline the federal permitting process. Despite substantial interest in the issue, Senator Manchin’s (D-WV) efforts to pass a bill failed twice in the Senate last year. He’s still committed to the goal, however. Just last week, he and Rep. Bruce Westerman (R-AR), the new chairman of the House Natural Resources Committee, were meeting to negotiate the details of a federal permitting bill.

Federal permitting reform remains a hot topic because of the recent massive investments in American infrastructure. All that investment will generate lots of cultural resources management work. As funding from the 2022 Inflation Reduction Act, in addition to the 2021 Infrastructure Investment and Jobs Act,  flows to communities across the country, there will be high demand to secure permits for new projects. This demand may keep public and Congressional attention focused on how to improve the federal permitting process.

House Republican leaders reportedly plan to unveil a major bill promoting greater energy production by promoting energy development on public lands, easing mining regulations, and streamlining the federal permitting process. Details of that legislation will likely become available in March, according to recent news reports. We’ll be on the lookout for any provisions that could threaten historic resources by narrowing the scope of impacts that are considered, reducing public involvement, or imposing unrealistic deadlines for environmental reviews.

We’ll also be mobilizing support for a bill to reauthorize the Historic Preservation Fund (HPF), which funds the work of State and Tribal Historic Preservation Offices, competitive grant programs, and the National Register of Historic Places. At present, Congressional authorization for this important program is set to expire on September 30, 2023. We will work with key members of Congress to support a bill that extends the authorization of the HPF and increases the total authorization level, which has remained unchanged since 1977.

As part of our efforts to secure funds for the national historic preservation program, we’ll be advocating for full funding of the new African American Burial Grounds Preservation Program, which was authorized in the omnibus spending bill last December. SHA members have advocated for this program over the past five years, and we will continue working to ensure its success.

In addition to monitoring legislative activity, SHA Government Affairs will continue working with the administration to develop regulations that enhance America’s historic preservation program. The administration’s plans for 2023 include revisions to several regulations that will directly impact historical archaeology: the rules governing the Native American Graves Protection and Repatriation Act (NAGPRA), Traditional Cultural Properties, and the U.S. Army Corps of Engineers (USACE) proposal to end its use of Appendix C. Each one of these proposals includes an opportunity for the public to weigh in on the changes under consideration.

SHA submitted a letter supporting many of the administration’s proposed changes to NAGPRA. We applauded efforts to ensure timely completion of the repatriation process, inclusion of indigenous knowledge, and a greater focus on enforcement. However, we also recognized that NAGPRA consultations involve significant amounts of work for tribes and urged the administration to identify sources of funding to help tribes complete the process. As the administration works to develop and stand up this new program, we will help keep SHA members and other stakeholders informed about each step of the process.

In the upcoming months, we’ll be submitting comments on the National Register Revised Bulletin 38: Guidelines for Evaluating and Documenting Traditional Cultural Properties. At present, the National Park Service is conducting consultation and outreach on the upcoming revisions. The deadline for comments is April 30, 2023, so SHA members have time to evaluate the proposed changes and raise any concerns they may have. We look forward to incorporating your feedback into a thoughtful, substantive comment letter this spring.

Finally, we are very pleased to see the USACE decision to rescind Appendix C, something that the Coalition has been urging the Army to do for several years. Appendix C procedures were never approved as a counterpart regulation by the Advisory Council on Historic Preservation (ACHP). The procedures have been problematic in several ways and have left the USACE vulnerable to litigation. Furthermore, the Appendix C procedures have been applied inconsistently across the country and have limited the USACE’s ability to be a good steward of America’s cultural heritage. According the new proposal, USACE would instead rely on ACHP’s regulations and joint USACE/ACHP guidance for implementation of Section 106.

The changed political landscape this year increases the likelihood of a highly politicized hearings and a robust debate on energy development. Prospects for enactment of any significant new legislation are low, however, given the power split in Washington and the compromises that would be required. SHA will continue working to support a strong historic preservation program through legislative lobbying and participation in the regulatory notice and comment process.

If you are interested in getting involved, please consider joining SHA’s Government Affairs Committee! If interested, please contact Terry Klein at or Marion Werkheiser ( We look forward to working alongside you to advance the protection of our historical archaeological heritage!

“Tech Appeal” in Coastal Archaeological Site Monitoring: Experiences with Terrestrial Laser Scanning and Photogrammetry in Northwest Florida

Nicole Grinnan, Research Associate, Florida Public Archaeology Network; PhD Candidate, University of St Andrews; with contributions from Jeffery Robinson, Master’s Student, University of West Florida

This blog post has been adapted from a presentation given at The Society for Historical Archaeology’s 2023 Conference on Historical and Underwater Archaeology in Lisbon, Portugal.

Though archaeology is sometimes accused of being a “dusty” science – both figuratively and literally – the field is constantly evolving as new technologies are adapted from other applications. Tools like ground penetrating radar (GPR), sub-bottom profilers, LiDAR, and laser scanners have revolutionized how archaeologists can efficiently and accurately collect data without even putting a shovel in the ground (or a foot on the seafloor). Accessible, advanced computing power in tandem with exciting software developments has also provided archaeology with the ability to process, store, and work with larger data sets.

In recent years, the Florida Public Archaeology Network (FPAN) has sought to integrate new technologies into its efforts to monitor archaeological sites at risk from the impacts of anthropogenic climate change. Many of these sites are located along Florida’s most vulnerable areas: its coastlines. In addition to concerns about “slower” climate impacts like sea level rise, the increase in devastating hurricanes striking the Florida coast have created urgency among many archaeologists in the state to get baseline records of these coastal sites before they are lost completely. In 2019, FPAN’s Northeast Region was awarded a Florida Division of Historical Resources Special Category Grant to monitor and record sites across the state through the Heritage Monitoring Scouts Florida (HMS Florida) community science program. While many of the sites visited during the duration of the grant (1,059 unique sites in total) were monitored using a standardized form, FPAN recorded 13 additional sites with its FARO Focus 350s Terrestrial Laser Scanner (Image 1). Outputs from these laser scans included point clouds, scaled 3D models and images of the sites, and Digital Elevation Models (DEMs). While only a small number of the overall sites monitored during the grant were able to be scanned, we now have a wealth of information on the status of those 13 sites at the time they were monitored.

Image 1. FPAN’s Nicole Grinnan and UWF graduate student Jeffery Robinson conduct initial set-up the TLS unit, which includes leveling the device prior to each scan. (Photo courtesy of Sandra Averhart, WUWF Public Media)

Image 1. FPAN’s Nicole Grinnan and UWF graduate student Jeffery Robinson conduct initial set-up the TLS unit, which includes leveling the device prior to each scan. (Photo courtesy of Sandra Averhart, WUWF Public Media)

During our initial experiences with terrestrial laser scanning (TLS) in Northwest Florida, a question inevitably arose: is this a technology that can be easily applied to archaeological site monitoring across the board? While numerous talented and tech-savvy archaeologists have successfully used TLS in their work, it struck me while in the field that TLS may not be the beacon of hope for site recording that we had initially hoped it might be. Not only are TLS units expensive to purchase in the current market (often somewhere along the order of $15,000+), but they also require costly periodic recalibration and proprietary software to remove point cloud data captured in the field. These expenses may be prohibitive for research institutions and governmental agencies unless grant funds can be spent to purchase a unit. While I can’t deny the ease of pressing a button and waiting eight minutes behind a dune to capture 360 degrees of data, TLS does also require a large kit of equipment that can be extraordinarily cumbersome to get to remote sites on land (Image 2). Units are sensitive to atmospheric conditions like humidity and temperature, with almost no resistance to water (a constant fear while working in Florida’s sudden, rainy onslaughts).

Image 2. FPAN’s Mike Thomin and Jeffery Robinson haul just some of the TLS equipment across Gulf Islands National Seashore. No mean feat, we eventually purchased the fishing cart to help us haul gear to sites like these. (Photo and animation courtesy of Nicole Grinnan)

Image 2. FPAN’s Mike Thomin and Jeffery Robinson haul just some of the TLS equipment across Gulf Islands National Seashore. No mean feat, we eventually purchased the fishing cart to help us haul gear to sites like these. (Photo and animation courtesy of Nicole Grinnan)

Originally designed for survey, construction, and architecture, TLS relies on the strong geometry of built environments – like right angles formed at the intersection of building walls or the high contrast between different construction materials – to align multiple scans during computer processing. Since a majority of the coastal archaeological sites we monitored in Northwest Florida were shell middens or Civil War-era earthworks, we installed white target spheres on our sites so that the TLS unit would have points with which to later align the scans (Image 3). The spheres added much more equipment to our overall kit and were often difficult to place on more tenuous landscapes like eroding bluffs. While scanning more “natural” sites like shell middens and Civil War-era earthworks was not an impossible task, it did provide for a more challenging day of scanning. In the case of sites completely covered in vegetation (as many sites are here in Florida), TLS was completely ineffective because it relies on “line-of-sight” observations.

Image 3. Koppa target sphere helped us create geometry fir TLS at sites along natural shorelines, especially in areas with significant vegetation.

Image 3. Koppa target sphere helped us create geometry for TLS at sites along natural shorelines, especially in areas with significant vegetation. (Photo courtesy Nicole Grinnan)

Aware of our experiences with TLS and having worked with it during his own projects, FPAN Public Archaeology Assistant and UWF Anthropology graduate student Jeffery Robinson proposed a Master’s thesis that would compare TLS with another technology now being used in a variety of archaeology applications: photogrammetry. Like TLS, photogrammetry produces point clouds of data that can be used to create products like 3D models, DEMs, or ortho-images. Unlike TLS, photogrammetry does not require any special tool or instrument; a camera and a good photo-taking strategy is generally all that is needed to capture data. Photo scales and printed targets can be useful in areas with low geometry (like natural shorelines), but they are generally not significant in terms of cost or equipment load. Processing images to create photogrammetric products may require the purchase of certain software, though open-source and free options are available (with some limits on functionality). With the quick swap of a camera lens, photogrammetry can also capture either large scale sites and environments or small, macro-scale artifacts. For his research, Jeffery selected three at-risk sites in Northwest Florida to monitor over the course of two years with each technology: Butcherpen Mound (8SR00029) in the Gulf Islands National Seashore Naval Live Oaks Area, Middle Middens (8ES04128) on Santa Rosa Island, and the World War I-era Battery Cooper (8ES00089) also in the Gulf Islands National Seashore Fort Pickens Area. Overall, photogrammetric recording of these sites took more time than recording via TLS. The reduced equipment load for photogrammetry, however, more than made up for the time needed to set up and level the TLS unit, install spherical targets, and transport the TLS unit to and from the site (Image 4). As neither TLS nor photogrammetry can collect data on occluded site components, photogrammetry is also less useful in places with heavy vegetation.

 Image 4. Mike Thomin photographs a site on Santa Rosa Island during a photogrammetric survey. Equipment for photogrammetry generally requires only a photographer, a camera, and photos scales or printed targets.

Image 4. Mike Thomin photographs a site on Santa Rosa Island during a photogrammetric survey. Equipment for photogrammetry generally requires only a photographer, a camera, and photos scales or printed targets. (Photo courtesy Nicole Grinnan)

Jeffery’s analysis of site change over time based on the TLS and photogrammetric data he produced is still ongoing, but our experiences in working with him drove home some of my early musings about whether integrating certain technologies into our everyday work was actually seamless. While I certainly don’t aspire to “singularity,” I felt that truly beneficial technology shouldn’t have myriad accessibility issues like cost, kit, and proprietary software. For that reason, recent efforts by FPAN to fully document sites in Northwest Florida have relied more on photogrammetry.

Though it may seem like this blog post is quick to dismiss the application of TLS in coastal sites monitoring based on our experiences, it is important to note that TLS can be extremely useful to record sites with high geometry (i.e., buildings and more built environments) that are accessible by road or paved path. One peripheral benefit of using our TLS unit in the field was that many passersby were extremely curious about what we were doing and how the technology worked. These impromptu outreach opportunities were excellent for discussing research with residents of and visitors to the area. Indeed, the use of TLS garnered so much attention that the local public radio station (WUWF 88.1) featured our efforts and Jeffery’s research in a three-part piece that won News Director Sandra Averhart first place in the 2021 Florida Association of Broadcast Journalist Awards in the Environmental Reporting Series category for radio (Part 1, Part 2, Part 3).

New technologies are incredible tools that archaeologists can harness to make their work easier and more efficient. As with many things, a cost-benefit analysis should be conducted prior to committing to one method. In the instance of utilizing Terrestrial Laser Scanning (TLS) or photogrammetry to monitor archaeological sites at-risk of climate impact in coastal Florida, staff in FPAN’s Northwest Region vastly preferred to photogrammetry due to its far more accessible nature. Given that the final products of both methods were virtually the same, we know how we’ll be packing for site monitoring missions into the foreseeable future.

North Carolina Archaeological Sites – Approaches to Handling Climate Threats

Allyson Ropp, Historic Preservation Archaeological Specialist, NC Office of State Archaeology; Ph.D. Student, Integrated Coastal Studies, East Carolina University

As I wrote about this time last year, North Carolina’s coastal archaeological sites are in a constant state of change. We are currently working to identify, document, and mitigate the effects of climatic change on these sites through different means. The complexity of North Carolina’s coastline and associated environmental changes make implementing standard mitigation and adaptation efforts challenging. This is not unique to North Carolina, but the struggle is evident in different sites across the state. Not only are our coastal sites facing erosion from storm surges, sea level rise, nuisance flooding, and increased stormy events, but they are facing areas of pooling water, saltwater intrusion, and the subsidence of the land. Throughout the coastal area, a considerable number of shipwrecks are also being impacted by these changing conditions, including sea level rise, storm frequency and intensity, and acidification. Each incident requires its own method to address the impacts on archaeological sites. Below are case studies outlining different approaches used to manage archaeological site changes to ensure their preservation.

Cape Hatteras Lighthouse

Cape Hatteras

An aerial photograph of the Cape Hatteras Lighthouse on the shoreline in 1999 with its path for movement laid out behind it (Photo Credit: National Park Service 1999).

Now a local and cultural landmark of the Outer Banks and managed by the National Park Service, the Cape Hatteras Lighthouse sits on the widest part of Hatteras Island. Hatteras Island is a barrier island. It is impacted daily by natural sediment transportation processes along the shoreline. As the sea level has risen, these daily processes and infrequent storm overwash have slowly moved barrier islands closer to the mainland and, consequently, closer to the original location of the lighthouse. The same processes are occurring today, as oceanfront vacation homes are falling into the ocean and major road closures occur almost monthly.

Several concerted efforts were made to protect the lighthouse from the encroaching seas and mitigate damage to the important and iconic structure. In the 1930s, the Coast Guard installed groins along the shoreline to support sedimentation. These groins are still visible today. However, while the groins may have supported sedimentation in some shoreline areas, they also supported erosion in other areas. This continued erosion caused the Coast Guard to move the light and abandon the tower. When the National Park Service took over management of the structure, they continued erosion control efforts, including groin building and beach renourishment. However, these were only temporary measures. In 1999, after years of public input and environmental impact studies, the National Park Service, with Congressional support, decided to move the lighthouse and its foundation inland one mile. Over twenty years after the first move, coastal erosion is still threatening the lighthouse, and moving the tower again may be back on the table.

Brunswick Town/Fort Anderson

Brunswick Town

Erosion at Brunswick Town/Fort Anderson State Historic Site. The left image shows the collapse of part of the Northern Battery and the installed rip rap to control continued erosion. The right image shows the water deterioration of the marsh and the southern end of the reefmaker system in the background (Photo credit: NC Office of State Archaeology 2021).

Brunswick Town/Fort Anderson State Historic Site is an archaeological site along the lower Cape Fear River. The historical site marks the first permanent settlement in the region, a major colonial and early-statehood port, and a Civil War Confederate fort. Following the end of the Civil War, the area fell out of use until it became an area of interest to archaeological researchers seeking to identify the location of the first permanent Lower Cape Fear River settlement. Since then, the site has become a part of the state’s Historic Sites and an area of continued archaeological exploration. The location, however, also exposes it to extensive threats from climatic change. The site faces erosion of major landforms and marsh coverage caused by daily sediment transport, storm surge, saltwater intrusion, water pooling, and land subsidence.

While most of the site is elevated above, major historically significant portions of the site are located on the shoreline, including two known colonial wharves and a battery wall. Initially, efforts focused on documenting the exposed archaeological components and collecting any artifacts that were evident on the surface. This allowed the site staff to understand the changes occurring. However, sustained extensive erosion around the colonial wharves and the partial collapse of the end of the northern battery led to the need for more comprehensive efforts. The team first installed rip rap and marine mattresses along the erosion areas to hold down the sediment. These temporary measures still allowed for continued erosion in these areas. Since 2017, the site staff have taken more extensive steps to support sediment accretion. They have installed reef-makers along the shoreline to attenuate the waves and support sediment deposition. Research and observational evidence have shown that this system is causing sediment deposition. This sedimentation has allowed for the stabilization of the archaeological site. However, it has facilitated the site’s coverage, making it impossible to recover information from the now-buried sections.

Shell Middens

Shell middens are a unique type of coastal archaeological site. In coastal North Carolina alone, there are approximately 600 shell middens that have been documented or are accounted for in the North Carolina site file. Shell middens (also known as shell heaps or shell mounds) are discard piles left by prehistoric communities. These middens consist primarily of used and discarded shells but typically contain other cultural materials, including ceramic, bone, and stone tools. The calcium carbonate in the shells helps create a more alkaline environment that allows for the preservation of the organic material housed inside the middens. However, their presence in coastal areas makes these middens vulnerable to environmental conditions. Sea level rise, shoreline erosion, wave energy, and storm surges have and will continue to alter these significant resources in coastal areas.

In the late 2000s-early 2010s, Lawrence Abbot, the Assistant State Archaeologist for the North Carolina Office of State Archaeology, undertook a study to identify the archaeological resources in the Coastal Plain that were susceptible to sea level rise. The study determined that of the 5753 archaeological sites within 30 feet of sea level, 581 had shell middens. Forty-two sites were also deemed eligible for the National Register of Historic Places. This desk-based study provided a basic inventory to begin future assessments of coastal areas. To effectively adapt to and mitigate the effects of climate change, it is first vital to know where known resources are and the threats they face. For example, this desk-based assessment only identified sites within 30 feet of sea level. It did not account for the hundreds of other archaeological sites in the Coastal Plain that may be impacted by other climatic conditions. But it provided a starting point for future analysis.

These case studies show a vast array of methods and measures that have been used to protect archaeological resources from the impacts of climate change. While some are more substantial solutions, the information and efforts at all these sites over the ability to learn new information before sites change states.


Linked References

Abbott, Lawrence E., Jr.

2011    The Office of State Archaeology Sea Level Rise Project: Initial Results and Recommendations Concerning the Adaptation for Cultural Resources to Climate Change. White paper for the Department of Cultural Resources. Reported by the North Carolina Office of State Archaeology.

Atlantic Reefmaker

2022    Brunswick Town/Fort Anderson Shoreline Protection Phase 1, 2, & 3A. Atlantic Reefmaker. Accessed 26 October 2022.

Hampton, Jeff

2019    Hatteras lighthouse may have to move again as Outer Banks shoreline continues to shift. The Virginian-Pilot. Accessed 26 October 2022.

Maine Department of Agriculture, Conservation & Forestry

2022    Whaleback Shell Midden: A thousand years of Native Americans seafood dinners. Bureau of Parks and Lands, Maine Department of Agriculture, Conservation and Forestry.,such%20as%20bones%2C%20ceramic%20pots%2C%20and%20stone%20tools. Accessed 27 October 2022.

National Park Service

2022    Moving the Cape Hatteras Lighthouse. National Park Service, U.S. Department of the Interior. Accessed 26 October 2022.

North Carolina Department of Transportation

2020    N.C. 12 to Remain Closed on Hatteras, Ocracoke Until at Least Tuesday Afternoon. North Carolina Department of Transportation. Accessed 26 October 2022.

North Carolina Historic Sites

2022    Brunswick Town/Fort Anderson. North Carolina Historic Sites, Department of Natural and Cultural Resources. Accessed 26 October 2022.

North Carolina Office of State Archaeology

2022    Brunswick Town Wave Attenuators. North Carolina Office of State Archaeology, Department of Natural and Cultural Resources. Accessed 26 October 2022.

Price, Mark

2022    Five-bedroom home collapses into ocean on Outer Banks, spreading debris along beaches. The News & Observer. Accessed 26 October 2022.

Ropp, Allyson

2021    Heritage in the Eye of the Storm – Hurricanes, Coastal Erosion, Sea Level Rise and the State of Coastal & Maritime Archaeology in the North Caroline Coastal Plain. Society for Historical Archaeology Blog. Accessed 26 October 2022.

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