Heater's Island (18FR72)


The Heater's Island site (18FR72) is located on an island in the Potomac River above the falls in Frederick County, Maryland. The Piscataway government and many of its nation's members had relocated to Heater's (or Conoy) Island by 1699 after finally being forced out of southern Maryland (many Piscataway and members of related groups, however, remained behind). Despite English aggression in dispossessing the Indigenous people of their land, the Maryland government desired to keep the Natives within the colony's boundaries. Many of the Piscataway led by the tayac (leader) accepted the offer to remain in the colony but chose to live on the island at a considerable distance from Annapolis.

Visitors sent to the island described a fortification measuring "fifty or sixty yards square" with "cabins" located both inside (18) and outside (9) the fort walls. Although the term "cabins" might bring to mind small, square log structures, cabin was a term often used to describe Indigenous dwellings and could refer to a structure erected in a traditional or familiar fashion. Indeed, a 1707 map of the Upper Potomac drafted by a German-born Swiss explorer depicts a longhouse-style structure near Heater's Island.

Twenty men, twenty women, and thirty children were reported present at the fort in April 1699, although some may have been "out a hunting." The two Virginians sent to the fort in 1699 concluded that the group could not have consisted of more than 80 or 90 bowmen. A second party sent in late 1699 confirmed the observations made in April and noted that the Piscataway had no intention of returning to live among the English. They cited as their reason that "foreign" or "strange" Indians would follow them and "doe mischief" for which the Piscataway would be blamed.

The Piscataways suffered a smallpox epidemic in 1705 that reduced their population. They nonetheless continued at Heater's Island, where a Swiss explorer encountered them in 1712. Baron Cristoph von Graffenried reported finding the Piscataways along with a French man, Martin Charetier, who had married an Indigenous woman and "was in great credit" among the Natives in the region.

Sometime around 1712, the Piscataways abandoned Heater's Island, with many moving to Conoy Town in Pennsylvania, where they remained until 1743.

Archaeological Investigations

Excavation trench, Heaters Island (Maryland Historical Trust)

Heater's Island was first documented in 1965 during a study of aerial photographs of the Potomac River aimed at assessing water quality. Carl Strandberg and Ray Tomlinson (1967) observed traces of what they interpreted as three "presumed colonial and two presumed Indian" fish traps near Heater's Island and the two researchers, who visited the island, reported seeing evidence of an Indian village (Curry n.d.).

This report led to limited test excavations at the site in 1967 by the George Washington University Anthropology Club. Although the investigations were never formally reported, interviews with the club's former president indicated that at least some artifacts, including beads, Native and European ceramics, and animal bone were recovered and that at least two post molds, a small hearth, and two small midden areas were observed (Curry n.d.).

In 1970, Heater's Island was the site of an archaeological field school taught by Robert L. Schuyler of the University of Maryland. On-site direction was provided by the late James Ivor Gross. An arbitrary grid was established at the site with the N0/E0 point in the approximate center of the site (as a result, some of the grid coordinates are rendered as negative numbers). A total of 120 5-by-5 foot test units were excavated at the site between March and August 1970. All excavated soil was screened through ¼-in. mesh (Curry n.d.).

Eighteen features were identified during the excavations, including at least one human burial and 17 additional deposits, the majority of which (with important exceptions) were pits. The exception was Feature 1, a "12-inch deep, slightly trapezoidal trench" that varied in width from 10 to 36 inches. Gross reported finding many artifacts in the trench fill; unfortunately, provenience information has been lost and the trench's artifacts cannot be separated from surrounding units. Gross interpreted this feature as a bastion or small house. Dennis Curry's subsequent assessment and analysis of the Heater's Island collection indicates that the feature is almost certainly the bastion for a fortification and that the fort's measurements fit well with dimensions of other forts reported in the literature (Curry n.d.).

Gross also reported documenting upwards of 800 post molds, ultimately deciding that only 60 of the 800 could be considered "good" post molds (post molds would disappear depending on the level of water in the soil, and many may have been root molds or rodent burrows). In general, due to a combination of factors including heat, dry soils, the occasional torrential rain, and a field school context, the site was not very well documented.

Block excavation, Heaters Island (Maryland Historical Trust)
Palisade bastion (Feature 1), unexcavated, Heaters Island (Maryland Historical Trust)
Recording the bastion excavation, Heaters Island (Maryland Historical Trust)
Post molds, Island (Maryland Historical Trust)

In 2004, Schuyler transferred the collection to the Maryland Historical Trust, where Dennis Curry has re-processed the collection and is currently preparing a final report on the University of Maryland excavations.


The Heater's Island collection consists of 4,269 artifacts, including lithics, ceramics, tobacco pipes, glass, beads, and a variety of metal artifacts, including 30 copper triangles.

Lithics are surprisingly few in number, with just 135 found in the database; of this number 79 are European flint. Curry concludes that the majority of non-flint lithics pre-date the Piscataway occupation based on the types and styles of projectile points recovered from the excavations. Forty-one of the 79 European flint fragments include gunflints.

The majority of ceramic fragments recovered from the site come from unidentified Native-made wares. Most of the fragments are too small to be reliably identified. Of those fragments that could be identified, ceramic types include Shepard, Page, Keyser, and Potomac Creek. Also present are Early Woodland ceramic types, including Marcey Creek, Selden Island, and Accokeek. With the exception of the Potomac Creek ceramics, which could be associated with the occupation of Heater's Island in the 18th century, the other types suggest that the island was known and occupied for decades if not centuries during the Early and Late Woodland periods.

European ceramic ware types number 281 fragments and include Manganese Mottled ware, Staffordshire slipware, tin-glazed earthenware, Spanish olive jar, unidentified coarse earthenware, Rhenish blue and gray stoneware, and English brown stoneware.

Both red and white tobacco pipe fragments were recovered from the excavations at Heater's Island, but white (or European-made) varieties far outnumber the red examples. Using the stem bore diameters of measurable pipes, Curry calculated a Binford date of 1692, earlier than the settlement's known period of occupation from ca. 1699-1712. Significantly, the pipe stem bores appear to skew larger not just at Heater's Island but at Zekiah Fort, perhaps suggesting variation in attributes preferred by Piscataway people when acquiring smoking pipes. A single pewter pipe stem was also recovered.

Glass artifacts derive predominantly from round wine bottles, although some fragments could be from square case bottles. Four dark green bottle glass fragments appear to have been worked with what appear to be retouch scars; all four examples form what Curry (n.d.) has identified as scrapers or cutting tools.

Glass beads included 402 specimens, most (as at Zekiah Fort) red or black in color. Many more seed beads occur in the Heater's Island assemblage than in the Zekiah Fort collection. This difference is especially magnified given that water-screening was not used at Heater's Island.

Most of the identifiable nails are wrought and complete examples range in length from 1.25 to 2.9 inches. At least six nails are clinched, with the point ends rolled, presumably after being hammered through boards in order to prevent snagging.

Other artifacts include lead shot, a large collection of gun parts, a Jesuit ring, a brass hawk bell, a brass jaw harp, a brass book hinge, brass tacks, brass buttons, brass scrap, brass triangles, iron knife blad fragments, and faunal remains.

The faunal remains from Heater's Island were analyzed by Elizabeth Moore, who found the assemblage atypical for a 17th-century Native American occupation. Deer and one raccoon are represented in the assemblage, but turkey, squirrel, and fish are absent. The assemblage includes a notably wide variety of turtle for a relatively small assemblage. A dog tibia exhibits cut marks indicating it was butchered for food, something that Moore indicates is uncommon for Native American sites.


Cissna, Paul Byron. 1986. The Piscataway Indians of Southern Maryland: An Ethnohistory from Pre-European Contact to the Present. Unpublished Ph.D. dissertation, Department of Anthropology, The American University, Washington, D.C.

Curry, Dennis C. n.d. "We Have Been With The Emperor of Piscataway, at His Fort:" Archaeological Investigations of the Heater's Island Site (18FR72). Ms. on file, Maryland Historical Trust, Crownsville.

Flick, Alex J., Skylar A. Bauer, Scott M. Strickland, D. Brad Hatch, and Julia A. King. 2012. "…a place now known until them:" The Search for Zekiah Fort. St. Mary's City, St. Mary's College of Maryland.

Graffenried, Christoph von. 1712. [Map of the] Project for the Establishment of a Colony along the Potomak River in Virginia and Maryland. In Landmarks of Old Prince William, by Fairfax Harrison. The Old Dominion Press, Richmond, Virginia, 1924.

Michel, Franz Louis. 1707. [Map of the Potomac above the Falls.] The Virginia Magazine of History and Biography 29(1):opp. p. 1.

Moore, Elizabeth A. 2013. Faunal Remains from 18FR72, Heater's Island. Ms. on file, Maryland Historical Trust, Crownsville.

Palmer, Wm. P. (editor). 1875. Calendar of Virginia State Papers and Other Manuscripts, 1652-1781, Preserved in the Capitol at Richmond. Virginia State Library, Richmond. Reprinted 1968, Kraus Reprint Corporation, New York.

What You Need To Know To Use This Collection

The conditions under which the site was tested and the subsequent curation of the collection before its transfer to the Maryland Historical Trust resulted in the loss of field records and the severing of provenience from the artifacts. The collection should be treated as a single assemblage.

Further Information About the Collection

The Heater's Island collection is owned by State of Maryland and curated by the Maryland Archaeological Conservation Laboratory. For more information about the collection and collection access, contact Rebecca Morehouse, Collections Manager, at 410-586-8583; email rebecca.morehouse@maryland.gov.

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