Catoctin Furnace is a group of archaeological sites associated with a 10,000-acre iron working furnace complex dating from the late 18th and 19th centuries in Frederick County, Maryland. The collection includes materials from the foundry site (18FR320), a springhouse site (18FR321), an African-American slave cemetery (18FR323), and a 19th-century miner’s house (18FR324). These sites were documented in 1977 during a Phase I survey by Orr and Son for the proposed dualization of U.S. Route 15 between Putnam Road and Maryland Route 77 in Thurmont. Catoctin Furnace represents a valuable resource for documenting the development of the iron industry in the United States and increasing understanding about the lifestyles and material culture of its workers.

Catoctin Furnace Foundry Site (18FR320)

The Catoctin Furnace Foundry Site (18FR320) is the location of a late 18th-/19th-century iron furnace. Among the principal activities undertaken there were refining iron and casting iron objects. In addition to the foundry, other associated structures and features, such as a mill raceway, a charcoal house, an unidentified structure, and an earthen storage dam, were also located and excavated.

Archaeological Investigations

Orr and Son excavated ten backhoe trenches and five test units at the foundry during their Phase I survey. Phase III investigations were undertaken by John Milner Associates (JMA) beginning in the summer of 1979. Nine backhoe trenches were excavated there to locate and explore architectural remains. Thirty-one five-by-five-foot test units were also excavated, and soils were screened through ¼-inch mesh only when deemed necessary for the recovery of small artifacts. A backhoe was then used to mechanically remove the top two feet of fill to reveal features. JMA conducted additional excavations in 1981. Three backhoe trenches and 29 partial five-by-five-foot test units were excavated using the same techniques as the 1979 investigation.


A total of 7,809 artifacts were recovered from the Catoctin Furnace Foundry Site, most reflecting the industrial function of the site. Ironworking activities at 18FR320 were primarily identified through the classification of tools, fragments of manufactured items, and slag. A large portion of the assemblage consisted of cast and wrought iron objects. Few non-industrial objects were recovered.

Archaeological evidence supports historical documentation that indicated that bombshells, pots, kettles, salt pans, iron stoves, and dutch ovens were produced at the foundry. A large percentage of the artifacts from 18FR320 were flat, featureless cast iron pieces, probably from plain stove plates. Two stove door latches, two stove feet, and a stove door frame were also recovered. The only decorated stove parts were ornamented along an edge to mask a joint. Fragments of various-sized cooking pots and kettles were also recovered, including an almost complete cast iron pot.

The types of tools and machinery hardware identified at the site indicated the iron working activities at Catoctin Furnace, and suggested the presence of a blacksmith. A variety of wrought tools, including 11 cold chisels, six files, three wrenches, two mold maker’s slicks, a hammer and a draw knife, were used on site to trim and finish iron castings. In addition, cast iron flask clamps, gaggers, runners, and wedge-shaped gates were also used during the casting process. The presence of horseshoes, ox shoes, and wagon parts confirm the use of draft animals to transfer ore and fuel to the furnace and to transport goods to various markets.

Evidence of non-industrial activities at Catoctin Furnace probably relate to the individuals who worked at the site. Five hundred and sixty-five ceramic sherds include coarse earthenwares, transfer-printed and annular whitewares, green-edged and blue-edged pearlwares, American stonewares, and hand-painted Chinese export porcelains. The bulk of glass bottles are colorless, with a few fragments of dark blue and green wine/beer bottles. In addition, a copper alloy powder flask with an embossed shell motif was recovered.


The Catoctin Furnace Records Collection has been divided into four areas by archaeological site number: the Foundry (18FR320); the Springhouse/Bathhouse/Raceway (18FR321); the Renner Burials (18FR323); and the Carty House (18FR324). Original records for all four sites are minimal, but those that exist are in good condition, with little dirt and staining. The collection is composed of four letter-sized archival clamshells, one oversized enclosure, and one document roll.

Excavation records for 18FR320 consist of daily field journals, plans, and profiles. They have been organized by year of excavation (1979 and 1981). For the 1979 excavations, only nine feature forms are present. All other records have been scanned as .PDF files, available online but not searchable. They include plans/profiles, bag and photograph logs, background research, elevation/depth records, notes on the basin dam, oversized maps, and other miscellany. There are two reports on the Foundry site: Archaeological Excavations at Site 18FR320 Catoctin, Maryland (Milner 1979), and A Report on the Excavation of an Ancillary Area (Site 18FR320) of the Historic Ironworking Complex at Catoctin Furnace, Frederick County, MD (Parrington and Schenck 1982). All type-written reports are available online in .PDF format and are word searchable.

Excavation records for 18FR321 are incomplete and have not been included in the database. All records have been scanned as .PDF files and are not searchable. They include plans/profiles, elevations, artifact catalogue packing and delivery lists, ceramic analysis, miscellaneous artifact analysis, geological reports, and miscellaneous maps. Two reports for the Springhouse/Bathhouse/Raceway are included: Interim Report of the Catoctin Furnace Archaeological Mitigation Project (Orr and Orr 1980); and The Catoctin Furnace Archaeological Mitigation Project Final Report of the 1979 Excavation (first, second, and final drafts) (Orr 1982).

There are no excavation records for 18FR323 (Renner Burials) and 18FR324 (Carty House). A small number of miscellaneous notes have been scanned as a single .PDF file. One report exists: Archaeological Data Recovery at Catoctin Furnace Cemetery (Burnston and Thomas 1981).

Photographs taken on-site or in post-processing are available through the online database, and are searchable using the above criteria. Researchers should note that images are not linked directly to specific documents, and photographic records do not necessarily exist for all features or units. Original images consist of slides, negatives, contact sheets, and prints, and are housed at the MAC Lab.


Burnston, Sharon A. and Ronald A. Thomas
1981     Archaeological Data Recovery at Catoctin Furnace Cemetery, Frederick County, Maryland. Report prepared for the Maryland Department of Transportation by Mid-Atlantic Research, Newark, DE.
John Milner Associates
1980     Archeological Excavations at Site 18FR320, Catoctin, Maryland. Manuscript on file at the Maryland Archaeological Conservation Laboratory.
Orr, Kenneth G. and Ronald G. Orr
1980     Interim Report of the Catoctin Furnace Archaeological Mitigation Project, Contract F522-152-770. Report prepared for the Maryland State Highway Administration.
1977     An Intensive Archaeological Survey of Alignment 1 Corridor, U.S. Route 15 from Putnam Road to Maryland Route 77 in Frederick County, Maryland. Report prepared for the Maryland Department of Transportation.
Parrington, Michael and Helen Schenck
1980     A Report on the Excavation of an Ancillary Area (Site 18FR320) of the Historic Ironworking Complex at Catoctin Furnace, Frederick County, Maryland. Report prepared for the Maryland State Highway Administration by John Milner Associates, West Chester, PA.

Digital Resources



Archaeological Report
Artifact Documents
Field Notes
Mapping Data
Photo Log
Project Documents

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An online archive of over 30 archaeological sites in Maryland, produced by the Maryland Archaeological Conservation Lab with the support of the National Endowment of the Humanities.