Erosion Threatens Cultural Resources at the 17th-century Calverton Site: Maryland’s Flood Awareness Month and Archeology Month Align

by Zachary Singer, MHT Research Archaeologist, and the Staff of Applied Archaeology and History Associates, Inc.

In addition to celebrating Maryland Archeology Month in April, Governor Larry Hogan proclaimed April 2021 as the first Maryland Flood Awareness Month. Although, April 2021 is the first official concurrent observance, 2017’s Archeology MonthAt The Water’s Edge: Our Past on the Brink addressed the effects of flood hazards on archaeological sites. In the 2017 Archeology Month Booklet, Jason Tyler of Applied Archaeology and History Associates, Inc. (AAHA) contributed an essay entitled “A Return to Calverton, or What’s Left of It”. In the essay, Jason described the results of a 2015 survey to document archaeological resources along the banks of Battle Creek in Calvert County and highlighted the impacts of shoreline erosion on the late 17th-century Calverton site (18CV22). Calverton was laid out in 1668 and served as the seat of government within Calvert County from 1668-1725. Jason concludes the chapter by advocating to protect the site from erosion and flood hazards and also to document the site through archaeology to learn about the threatened cultural resources at Calverton.

The Calverton Shoreline, 1682 vs. Today

Following Jason’s recommendation, the 2017 and 2018 Tyler Bastian Field Sessions with the Archeological Society of Maryland were held at the Calverton site to investigate the site before storm-surge flooding and the wind-driven waters of Battle Creek further eroded what evidence remained of the town. The field sessions focused on ground-truthing anomalies identified during a magnetic susceptibility survey by the MHT Office of Archaeology. The Field Session investigations identified a part of the Colonial town that had not entirely washed into Battle Creek, including intact sub-plowzone cultural horizons and features. In the summer of 2020, AAHA conducted supplemental archaeological investigations at the Calverton Site to continue documenting those portions of the site at highest risk from shoreline erosion and flooding caused by sea level rise. The 2020 work was supported by the Calvert County Government and a grant from the Maryland Heritage Areas Authority.

Magnetic Susceptibility Data Collected by the MHT Office of Archaeology

Prior to AAHA’s 2020 field investigations, the MHT Office of Archaeology conducted a ground penetrating radar (GPR) survey within 10 meters of the eroding bank overhanging Battle Creek to identify anomalies in the area of the site most at risk to further loss from wind and water action. The GPR essentially uses a 350MHz (megahertz) antenna to send radio pulses into the ground which bounce off of subsurface anomalies and return to the antenna. Through the use of special software, the data collected by the GPR operator can be used to create a detailed 3 dimensional model (called a 3D time slice) that reveals both the horizontal and vertical relationships amongst radar anomalies including potential cultural features (trash pits, cellars, privies), potential modern disturbances, and natural tree root systems.

MHT archaeologists identified seven likely anthropogenic features via examination of the radar time slices. There were two large rectilinear anomalies in the eastern portion of the survey area. A deep, roughly circular anomaly near the center of the survey area was interpreted as a possible well. To the west of the possible well was an irregular anomaly that corresponded with a magnetic aberration identified during a 2019 gradiometer survey. To the east of the possible well was another amorphous anomaly. One trench-like linear anomaly was identified running roughly north-south in the western portion of the survey area. Additionally, one irregularly-shaped anomaly appeared in the southwest corner of the survey area and roughly corresponded to the location of a feature identified in 2017: a cluster of artifacts partly eroding from the bank of Battle Creek. In addition, the rectangular footprint of a test unit from previous excavations was identified, confirming the projection of these anomalies in real space. All seven potential cultural features were recommended for ground-truthing during AAHA’s 2020 archaeological fieldwork.

In total, AAHA excavated eight Test Units during the 2020 fieldwork to assess the form and function of the GPR anomalies. The excavations resulted in the identification of ten cultural features and the recovery of 3,369 artifacts mostly dating from the late 17th and early 18th century including tobacco pipes, a Charles I sixpence coin (1639-1645), and sherds of tin glazed earthenware. Of the ten features identified and excavated by AAHA in 2020, seven are related to the occupation of Calverton most likely from the late seventeenth century and the first quarter of the eighteenth century. The largest and most artifact-dense features related to the colonial occupation of Calverton were identified in the central portion of the study area and represent a posthole/mold (Feature 15/22), a small cellar (Feature 14 – the anomaly originally thought to be a possible well), and a possible trash pit (Features 16 and 17). Also identified was a small trench or ditch feature for what was probably once a paling fence in the western portion of the study area (Feature 19).

The 2020 archaeological investigation at Calverton provided additional data crucial to understanding the colonial occupation of the town in the portions of the site most vulnerable to flooding and erosion. Most significantly, it identified a previously unknown cellar (Feature 14) and an associated post hole/mold (Feature 15/22) both of which likely reflect the location of a colonial structure. While the small window into this structure excavated to-date has allowed some preliminary conclusions to be drawn, additional excavations could further reveal the size, layout, and function of the former building. Additional excavation and GPR survey in the vicinity of the paling trench identified during the 2020 investigation (Feature 19) could also provide valuable data on lot divisions in Calverton and colonial towns as a whole.

Another important aspect of the 2020 project was to monitor the shoreline at Calverton to continue assessing the risk of the site to the destructive power of wind and water action along Battle Creek, which remains an imminent threat to the archaeological resources at the site. MHT map projections show that the town’s important public buildings, including the courthouse and chapel, have already been lost to Battle Creek. AAHA’s comparison of the 2020 location of the Battle Creek bank to the location recorded by a 2017 Calvert County LiDAR survey shows shoreline loss ranging from 0.0313 meters to 3.204 meters, with an average of 1.333 meters of loss over two years, or 60- 70 centimeters per year. Most alarmingly, seven of the 28 points taken for the analysis (25% of the total) show shoreline loss in excess of 2 meters and these points occurred over the entire length of the surveyed shoreline. At this rate, the late 17th/early 18th-century cellar feature (Feature 14) will be lost to erosion by 2028 without intervention. With climate change comes increasing numbers of catastrophic storms. Tidal surges during such storm events can wreak havoc on the shoreline, severely undercutting the bank at Calverton.

Map Depicting the Rate of Shoreline Loss at Calverton between 2017 and 2020

This reinforces the urgent need for additional archaeology at Calverton before the resource is entirely lost. Maryland Flood Awareness Month aligning with Maryland Archeology Month provides the perfect opportunity to discuss the impacts of flooding on archaeological resources. To learn more about planning efforts to protect archaeological sites from the impacts of flood hazards, please see the MHT’s guide for Planning for Maryland’s Flood-Prone Archeological Resources.

Preserving Chesapeake Heritage: Navigating the Tubman Landscape amid Rising Tides

By Jessica Brannock, Communications Intern

In 2007, roughly 17 acres of wetlands within Blackwater National Wildlife Refuge (NWR) were dedicated to create the Harriet Tubman Underground Railroad (HTUR) State Park. These lands and waterways where Tubman lived and worked as a young woman, enslaved by the Brodess family, make up just a fraction of the 25,000 acres of land in Dorchester County dedicated to the HTUR National Monument. While the park’s Visitor Center offers exhibits on the life and heroism of Tubman, the true monument to her legacy is the landscape itself—and it’s disappearing.

Over the course of a decade, Tubman returned to this landscape 13 times and guided 70 slaves to freedom. Hiding in the marshes by day and traveling by foot and boat at night, Tubman and other freedom seekers relied on their knowledge of Chesapeake waterways, plant, and animal life to survive the journey north.

Visitor Center

Harriet Tubman Underground Railroad Visitor Center, LEED silver certified, and constructed on higher ground to protect the building against rising sea levels.

Today, much of the wildlife found in the brackish tidal marshes and hardwood forests of Blackwater NWR are typical of what Tubman encountered over 150 years ago. However, preserving these habitats and heritage is an ever-present challenge as wetlands throughout the Chesapeake Bay watershed are threatened by environmental change.

Current water levels in Blackwater NWR are much higher than when Tubman navigated the rivers and marshes to freedom. Since the NWR’s establishment in 1933, over 5,000 acres of wetlands have been lost to sea level rise.

Marshes act as buffers between land and water, filtering out toxins and absorbing the forces of storms and tides, and Tubman would have been familiar with the tidal rhythms that flooded the wetlands with saltwater and ebbed back with the flow of freshwater tributaries. As sea levels rise, however, saltwater mingles more heavily with fresh, destroying salt-sensitive plant-life as marshlands erode and give way to flooding. By the end of the century, climate science predicts that sea levels will rise in the Bay region between 3 and 4 feet.

Saltwater Intrusion 4

Patches of bare forest and exposed tree roots, destroyed by saltwater intrusion are reminders of rising tides, and the imminent loss of habitat that follows.

The HTUR Visitor Center was constructed with the vulnerability of the landscape in mind. The building is sustainably designed to LEED silver standards and includes bioretention ponds, rain barrels, and vegetative roofs. Located near the Little Blackwater River, where Tubman worked checking muskrat traps as a child, the site was strategically elevated, placing the building on higher ground—a precautionary measure against the accelerating rate of sea level rise. With nearly 300 acres of marsh within the NWR lost each year, the wetlands could be fully submerged by 2050.

Actions can be taken to slow the loss and preserve the landscape so valuable for its habitat and history. In 2017, the Conservation Fund, U.S Fish and Wildlife Service, and National Audubon Society partnered to raise 40 acres of marshland within the NWR. This thin-layering process spread 26,000 cubic yards of sediment dredged from the Blackwater River across the wetlands, raising the marshes by 4-6 inches. Along with large scale tree and marsh grass planting, these efforts will help reduce the pace of flooding over the next decade.

As tides rise, the landscapes that hold our heritage will continue to suffer losses to their environmental and historical resources. In the coming years, we must acknowledge environmental threats and face them head on, so that future generations may continue to experience and interpret the legacy of our national treasures.

Watching Irma

By Nell Ziehl, Chief, Office of Planning, Education and Outreach

As Hurricane Irma bears down, threatening southern Florida, I keep returning to what is precious about that place for me. My family and many of my childhood friends live in Tampa and St. Petersburg, well within the vulnerable area recently highlighted by the Washington Post. I was born there, not too far from where my mother and my grandmother were born. The connection is live, and I’m worried about my people.

But what else persists? From my great-grandparents’ time, some buildings still stand. My grandmother’s house still stands, I think. Emotionally, I can’t separate the historic bungalow cottages from the live oaks or from the pelicans standing on the bay’s stone wall. The pink bricks that pave my sister’s street warm and glow in the sun — the fabric and the light are equally important. Every year, our family gathers at the beach in one of the few small-scale, family-run motels left, a few doors down from the Don CeSar, a towering remnant of Florida’s early resort industry. Although the Gulf itself draws us, still full of life and beauty, these places also matter – the human record of their construction, their imprint of time and place, the memories and attachments formed there.

IMG_1395

The author’s family in St. Petersburg

At the same time, our cultural heritage includes a heritage of loss. We understand that hurricanes come and go and that buildings, piers and even roads are ephemeral. Left alone, the landscape will reconquer. And behaviors also persist. After generations of weathering storms, many locals do not evacuate, despite news that the storms are not the same. Even armed with better knowledge about water management and the importance of ecosystem restoration to protect inland areas (not to mention the biological habitat and tourism dollars), Florida continues to permit development in ways and in places that are unsustainable, potentially exacerbating disasters and jeopardizing recovery.

IMG_4145

The Don CeSar after a thunderstorm

As we move forward into an uncertain future, with climate change fueling rising tides and more dangerous storms, we must adapt in ways that take all of these elements into account. What is the spirit of the place? What should we protect? What *can* we protect? And what do we need to change?

Too often, our regulatory and philosophical frameworks force divisions between the “built environment” and the surrounding ecosystems, even though the full character of a place includes the architecture, infrastructure, streetscape, waterways, plants, animals – and the people who live there. Cultural heritage is cultural memory, and that includes traditional and historic ways of adapting to the natural environment, including storms. And when buildings collapse, when the tangible fails, the intangible remains valuable and can inform a more resilient future.

IMG_1483

A saw palmetto preserve

Preservationists sometimes focus on limiting rather than accommodating change. But we, more than many other professions, have the ability to understand the evolution of a community over time and to help manage change in ways that protect quality of life and respect the character of place. I pray that Irma passes by without much damage. But more storms will come, and how we respond and rebuild will determine what we can carry forward.

Preparing for Future Floods

By Nell Ziehl, Chief, Office of Planning, Education and Outreach

IMG_3652

Hoopers Island

As we turn from Ellicott City’s disaster response to recovery, and watch hurricanes threaten Florida and Hawaii, it’s hard not to think about all the places throughout Maryland that are prone to flooding. We built our earliest towns, cities, roads and rail lines along the Chesapeake Bay and its tributaries. As ports and fishing industries boomed, we developed more. And let’s be honest: we all love to live and play near water. Continue reading

2016 Cultural Resources Hazard Mitigation Planning Grants Awarded

With funding from the National Park Service Hurricane Sandy Disaster Relief Fund, the Maryland Historical Trust has awarded seven grants throughout the state to help protect historic places and archeological sites from future storms. These grants will be supported by the Trust’s Cultural Resources Hazard Mitigation Planning Program, which was created to assist local governments to better plan and prepare for the effects of coastal storms and other hazards that impact historic places and properties. The grant projects are described below.

Anne Arundel

Early 20th century vernacular home common to Shady Side

Anne Arundel County Trust for Preservation, Inc., Phase I Hazard Mitigation Planning for Anne Arundel’s Cultural Resources: $32,000
Three areas in the county (Shady Side and Deale; Pasadena; and Maryland City, Laurel, and Jessup) face the highest risk to flooding and contain the most undocumented historic structures, as well as unsurveyed potential archeological resources. To remedy this, the Anne Arundel County Trust for Preservation will conduct a study to identify historic structures and archeological sites and evaluate the potential damages caused by flooding. Continue reading

Smith Island Looks to Its Future

By Jen Sparenberg, Hazard Mitigation Program Officer

Smith Island Historical Marker

Most Marylanders know Smith Island cake is Maryland’s official state dessert, but a few things about Smith Island folks likely don’t know are: it’s only accessible by water; it’s one of the oldest continually occupied colonial settlements; its isolation has preserved the culture and language patterns of its earliest colonists; the Island and surrounding bay marshes have been periodically inhabited since 10,800 BC, and that Smith Island is actually comprised of three different communities:  Ewell, Rhodes Point, and Tylerton. Continue reading