F is for forts, feature, flint, Friday!,and fire-cracked rock

This week our focus will be on fire-cracked rock. Over the past two years of blogs we have frequently used the term fire-cracked rock and have described it at varying degrees of detail. We thought this week we could explain how fire-cracked rock is made and how its presence is an indicator of human activity on archaeological sites.

Fire-cracked rock is often associated with the Transitional Period which occurred about 3,000 - 4,000 years ago in Pennsylvania. Climatic changes which are thought to have occurred during this period led to a warmer, drier period which allowed for hunter-gatherers of the late Archaic (4200-6000 BP) period to become more sedentary and to occupy sites closer to rivers and streams for longer periods of time.

Many of the Transitional period sites contain extensive scatters of fire-cracked rock, that is, rock that has been exposed to extreme heat, causing it to break into angular pieces. Some of this is the result of normal cooking, as rock was often used in fire pits to radiate heat for roasting meat and other foods. Also, heated rocks were thrown into holes in the ground, lined with hide and filled with water, as a method for boiling foods. The large accumulation of fire-cracked rock on Transitional Period sites suggests that food was being cooked for large groups, and possibly during relatively long periods of site occupation.

Simply stated fire-cracked rocks are rock that are cracked or broken due to their use in either the boiling or roasting of foods.

Fire-cracked rock in alignment for mending, note the sharp angular breaks.

These fire-cracked rock have been refitted to allow for analysis of the distribution of the FCR across the archaeological site on which they were found.

Research conducted on these large fire-cracked rock features have provided archaeologists with comparative data allowing for analysis of the function of these features. At the Kettle Creek East site (36Cn199) a series of seventeen features were examined and radiocarbon samples were obtained on ten of the seventeen features. Nutshells of hickory, hazelnut and walnut as well as calcined (heavily burned) bone fragments were sampled for the resulting radiocarbon dates. Assays from these samples produced evidence of two occupation episodes ca. 3400 BP and ca 3050 BP, placing both of these in the Transitional period.

On the left is a wide, flat bottomed basin roasting pit. On the right, is a shallow basin hearth.

Functional interpretations of these seventeen features based on previous research by archaeologists provided a comparative model for identifying the function of these fire-cracked rock features. Most of the features were identified as hearths, some smaller hearths did not contain fire-cracked rock, larger hearths were classified based on their shallow basin shapes with an abundance of charcoal and the size of the fire-cracked rock fragments, two of the remaining features contained rock that were more angular- suggesting a repeated heating and rapid cooling associated with stone boiling. The video link at http://www.youtube.com/watch?v=RrlQwCxfvuU clearly demonstrates this process.

Petraglia, Michael, Dennis Knepper, and John Rissetto. "The Nature of Prehistoric Activities on Kettle Creek, An Upland Tributary of the West Branch of the Susquehanna." Journal of Middle Atlantic Archaeology 14 (1998): 13-38.

For more information, visit PAarchaeology.state.pa.us or the Hall of Anthropology and Archaeology at The State Museum of Pennsylvania .

History Remembers Us by What We Leave Behind

Featured periodically in our blog are collections produced as a result of archaeological investigations conducted by contract archaeology firms. A recently received collection was the product of an investigation and subsequent excavation undertaken prior to the expansion of the Pennsylvania Convention Center in Philadelphia. John Milner & Associates (JMA) conducted this investigation between early May and late June of 2007 in center city Philadelphia. The resulting collection produced from this project includes a wide array of historic ceramics, glass and personal effects that are the physical connection to many of the peoples whose toils led to the early industrialization of Philadelphia. More importantly they represent a working class of peoples often not represented in historic documents, but whose legacy continues through the refuse they left behind.

Historic background research conducted by JMA identified early residents of the neighborhood on Arch Street, where we will concentrate our discussion, as professional and middle-class. The surrounding businesses and residents were comprised of physicians, a silver smith, brick yard, cigar maker, boot & shoemaker and numerous other artisans. This homogenous mix was a reflection of the immigrants settling in Philadelphia and an important foundation in the development of the city. The transition of this neighborhood from a mix of professional and skilled labor to one of industrial and commercial establishments is reflected in the wares recovered from this archaeological investigation. Our focus this week will be on the residents of 1327 Arch Street.

Research of deeds and census records for the property records it as early as 1783, with multiple owners. Of note in this deed trail is John Hinckel a city potter on record in 1792 as owner of the property until 1851. The first deed record of a residence at this location was in 1853 when Robert Cresswell purchased the property containing a “four-story messuage”. JMA describes the residence as a long narrow 4-story brick building with a narrow open yard. Cresswell’s occupation is a merchant before becoming a wallpaper manufacturer. Census records indicate the Cresswells lived in the home until the late 1800’s when Robert’s will transfers ownership to his wife. The neighboring residences also undergo a change in occupation and by the turn of the century the middle-class have moved out and are replaced by the working class. Residents of the house include individuals listed as renters and boarders. Their occupations range from mailman and clerk to servant. Included in the list of residents are three black servants. The census and deed records document the frequent change in residents and the change in ownership over the next forty plus years. The Creswell’s home transitions from a large private residence to the Hotel Lenox in 1925 which operates for about ten years at this location.

JMA’s excavations of this house lot documents numerous archaeological features including a midden, builder’s trench, and a brick foundation at the rear of the property. Archaeologists from JMA observed both intact and disturbed portions of the property as a result of demolition and construction projects on the lot. Investigations at 1327 focused on two primary features; the midden commonly known as a trash/refuse pit and a brick foundation.

Map from JMA of features on house lot at 1325 and 1327 Arch Street

Located adjacent to the brick foundation was a deposit identified through observation of soil changes during excavation by archaeologists as an undisturbed remnant of yard. JMA also noted changes in the soils around the brick foundation and observed construction trenches which cut through the surface. Further confirmation came from the artifacts found within this unit. Ceramics, glass and dietary waste recovered from this unit indicate activities on the property prior to the first recorded residence in 1853. Included in the refuse were fragments of slip decorated redwares, pearlwares, kaolin pipes,clam and oyster shells, along with beef, pork, chicken and turkey bones. Also recovered by archaeologists were fragments of saggers and a waster. Both of these items are often products of kilns and pottery manufacturing. Saggers are large, thick walled clay vessels that protected the pottery while it was being fired. Wasters are ceramic pieces that were damaged in the firing process and may have broken or were unacceptable for some other reason.

Recall that deed records indicated that a potter, John Hinckel, had owned the property prior to the first recorded occupation of the lot by the Cresswells. The address for his shop is recorded at South 7th and 8th Streets on Market Street in a 1791 census. Historic documents for the development of Philadelphia indicate that Arch and Market streets became the desired areas for the middle class at the turn of the century. While the background research does not document Hinckel residing at 1327 Arch Street, the artifacts recovered indicate he either resided here or possibly operated a pottery at this location for a period prior to selling the property. Research does not indicate if Hinckel was a redware potter, but Philadelphia is long known for its German redware potters.

Historic ceramics excavated from Feature 2.4, slip decorated redware on the left and decorated pearlwares on the right.

If Hinckel occupied this location for a period of time, might other structural evidence be buried under the debris encountered by JMA archaeologists? Investigations continued to focus on this lot with excavations of a multiple bay brick foundation adjacent to the now excavated midden. This foundation was just over 17 feet long and approximately five feet wide.

Brick foundation at rear of house lots 1325 and 1327 Arch Street

Excavations of this feature revealed a series of five chambers filled with demolition debris and ash. Archaeology revealed that this structure was shared between the residence of 1327 and 1325 Arch Streets at the rear of the residences. In the upper layers of ash fill the top of a large ceramic vessel was unearthed and the prospect of answering the occupation questions encouraged JMA archaeologists involved in the project. Would this vessel help to date the foundation and was it contemporary to the intact yard surface?

Excavations of the interior of the brick foundation exposed the top of a large ceramic vessel

If we are known by what we leave behind- in either our material culture or our personal deeds what other evidence of the occupants of 1327 Arch Street might an investigation of our remaining feature provide?


To be continued next week….




For more information, visit PAarchaeology.state.pa.us or the Hall of Anthropology and Archaeology at The State Museum of Pennsylvania .