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Example Projects

New Discoveries at St. Mary's City, Maryland
Locating the first English colony at St. Mary's City, MD

HAP has successfully located and mapped the site of St. Mary's Fort, the first permanent settlement constructed by English colonists in 1634. Following topsoil magnetic susceptibility and magnetometer surveys that helped to determine areas of former occupation, a high-resolution ground-penetrating radar survey (33 miles of data!) produced clear evidence for a rectangular palisade with a distinctive bastion projecting from one corner. This work was undertaken for Historic St. Mary's City and was funded by a grant from the Maryland Historical Trust with matching support from the Historic St Mary’s City Foundation.

Follow the link for further details on the discovery, its significance, and the new collaborative People to People project between Historic St. Mary's City and members of the Piscataway community.

Horsley conducting GPR at St. Mary's City

Additional media coverage:  Washington Post   Smithsonian Magazine   Telegraph (UK)   Ancient Origins   Fox News   WBALTV11  

Composite of selected GPR time-slices corresponding to 0.8-0.9 and 1.1-1.2 meters below surface. At these depths the outline of the palisade is clearly visible, with a bastion on the western corner. The dark band across the northern edge where the ground begins to drop away is caused by a natural gravel layer and unfortunately prevents sections of the palisade from being distinguished. (Pre-17th century erosion gullies can also be seen bisecting this gravel deposit.)

The accompanying simplified (and deliberately incomplete) interpretation highlights many of the identified postholes (from all depths), as well as probable structures associated with the fort (red) and later occupation (blue); the latter are seen to be aligned with the late-17th century town that grew up outside the fort. A large pit or possible cellar is visible within the bastion (purple) and could either relate to the fort or later activity.

The GPR survey was conducted using a GSSI UtilityScan GPR system along transects spaced 0.25m apart. Data were processed using GPR-SLICE.

Locating unmarked burials
Locating and mapping unmarked burials - Washington Monumental Cemetery, South River, NJ

A high-resolution ground-penetrating radar (GPR) survey was undertaken at this cemetery in 2018 to test a local tradition that victims of the 1918 Spanish Influenza epidemic were buried here. Despite this section of the historic cemetery containing very few grave markers, the GPR survey revealed almost 400 burials neatly arranged in rows. The image to the right shows many of these burials as dark anomalies caused by buried voids and soil disturbances. The few grave markers present are shown as red crosses.

It will  be necessary to conduct further research to determine whether these are indeed influenza victims from 1918-19, although various lines of evidence suggest that this is likely the case. These results will also help the community decide how best to mark and commemorate these individuals.

This work was done in partnership with the South River Historical and Preservation Society, and Washington Monumental Cemetery with funding by the Middlesex County Board of Chosen Freeholders and the New Jersey Historical Commission, Department of State.

Media coverage
Mapping an 11th century village - Washausen Site (11MO305), Monroe County, Illinois

An 8 hectare (20 acre) high-resolution magnetometer survey of the Washausen site has provided a near-complete map of this 11th century mound center in the American Bottom. In addition to one of the square platform mounds and the relatively 'clean' central plaza, the results clearly reveal the arrangement of numerous house basins, visible due to the enhanced magnetic soils of their fills. As observed through excavation at other sites, many of these basins are seen to be clustered around small courtyards. Variations in the size, shape, orientation, and location of these structures may indicate differences in function or social or political differences across the site. These results have been used to define new research questions about the site, and to help locate excavation units.

Mapping a Native American village

This work was conducted for Dr. Casey Barrier as part of his doctoral research at the University of Michigan. The results have been published in American Antiquity and Archaeological Prospection.

Revealing structural details - Morton Village Site, Fulton County, Illinois
House basins & wall trench structures

Magnetometer and GPR surveys have been undertaken at this Mississippian and Oneota village site since 2010.  Around the periphery of the settlement, wall trench structures and house basins are randomly oriented and loosely clustered into groups with associated pits.

Despite disturbance relating to a 20th century farm close to the center of the site, the core of the Native American village is characterized by rows of closely packed basin structures with similar orientations. Modern ferrous disturbances reduce the effectiveness of magnetometry in this area, and so a high-resolution GPR survey was undertaken to obtain a clearer picture of houses and basins in this area. A 200 MHz antenna was used to collect data along traverses spaced 0.2m apart. This allows small features such as narrow trenches to be distinguished, providing significantly more detail than the magnetometer survey. It is even possible to identify one basin structure that cuts into an earlier basin (top center).

This work has been undertaken by HAP for the Dickson Mounds Museum and Michigan State University.

Barton Site, Allegany County, Maryland, USA
Enclosed habitation on a floodplain

Large-scale, high-resolution magnetometer surveys were conducted at locations along the North Branch of the Upper Potomac in Western MD in 2009 to assess the potential for locating and evaluating archaeological sites on alluvial terraces. At the multi-component Barton site (18AG3), owned by the Archaeological Conservancy, the results have dramatically enhanced and altered the interpretation of the site. In addition to adding detail to a known enclosed Late Woodland (Keyser phase) village, this survey also revealed three additional and previously unrecognized settlements with palisades along this 12-hectare section of floodplain. The results also illustrate the distribution of buried cultural resources across the landscape, including more deeply buried remains--possibly older--on the lower terrace, as well as geomorphological information that helps to place these sites into their landscape. This work was sponsored by the Maryland Historical Trust and Towson State University.

Revealing a colonial house and landscape
Notley Hall, St. Mary's County, MD, USA

The site of Notley Hall in Southern MD provided an opportunity to demonstrate the range of information that can be provided by different geophysical techniques. Thomas Notley, Maryland Deputy Governor, constructed a  house at this site in around 1672. His 1679 inventory describes the house as T-shaped, and provides a detailed room-by-room account of this substantial house. It also describes an "old hall" that may have been an existing dwelling that Notley first inhabited. 

Following a shovel test pit survey by St. Mary's College of Maryland, several geophysical methods were applied across the same area for comparison. These included: a topsoil magnetic susceptibility survey (at 5m, 10m, and 20m intervals); magnetometry (at a resolution of 0.125m x 0.5m), GPR surveys with 400 MHz and 200 MHz antennas; and earth resistance (twin-probe array with 0.5m mobile probe separation, at 0.5m x 0.5m). Examples of the results of these are shown below, revealing the clear outline of the T-shaped house--with full basement throughout--and a brick or tile drain extending to the WSW. An intense area of small-scale magnetic 'noise' to the south of the main house likely indicates the location of the earlier dwelling. This work was funded by St. Mary's College of Maryland, and further information on the site may be found at the Colonial Encounters website.

Mapping a 19th-century mansion
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