FREE Lecture – Last Days of Lincoln

From Noreen McCann, Historian and Visitor Services Manager at Sully Historic Site:

Civil War Lecture Series at Sully Commemorates Sesquicentennial

 As the 150th anniversary of the American Civil War draws to a close, Sully Historic Site presents an evening lecture series this spring. This Civil War commemorative program is sponsored by the Sully Foundation, Ltd. in memory of Thom Fitzhugh Hanes, one of the original founders. Each evening, historians present a look at different aspects of the final year of the war.

 n Tuesday, April 14, Charles Teague will give insights into President Abraham Lincoln’s last days in April 1865. In “The Final Fourteen Days of Father Abraham” he seeks to see what Lincoln saw, who he met with, how he felt, and what his demeanor was during those two tumultuous weeks. Hear some fascinating experiences, some of which are little known. Teague is a Ranger at Gettysburg National Military Park, author, speaker and long-time researcher on Lincoln and Gettysburg.

The talk will be held at 7 p.m. in the Eddie Wagstaff Room at the Sully Visitor Center. Sully is the 1794 home of Richard Bland Lee, northern Virginia’s first congressman and uncle of Robert E. Lee. Light refreshments will be served. The talk is free, however donations are gratefully accepted. Space is limited. Call to reserve your seat now. For more information call 703-437-1794.

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Fire-Cracked Rock, part 1

Interior of Fire-Cracked Rock Old Colchester Park & Preserve Fairfax, Virginia

Interior of Fire-Cracked Rock
Old Colchester Park & Preserve
Fairfax, Virginia

Exterior of Fire Cracked Rock Old Colchester Park & Preserve Fairfax, Virginia

Exterior of Fire Cracked Rock
Old Colchester Park & Preserve
Fairfax, Virginia

by Sheila Koons – Lab Archaeologist & Lithic Specialist

One of the most common artifacts recovered from Old Colchester is fire-cracked rock (also known as FCR), particularly from the prehistoric areas. Not all cracked rock is indicative of human activity. So then how can we tell if the rock was cracked naturally or by purposeful humanly-controlled fire?

First, it is important to be able to identify fire-cracked rock. Fire-cracked rock is usually quartzite, sandstone, or granite, and is found fractured and split (McDowell-Loudan 1983:24). The majority of fire-cracked rock at Old Colchester happens to be quartz which is a raw material that is abundant in the area. FCR typically retains the exterior or cortex of the cobble, the fractured interior surfaces are crenulated, and the fracture edges are jagged and angular. The cortex may take on red, pink, or black color or it may not change color at all. When quartz is heated, the increase in temperature causes the internal development of fissures and water loss which in turn cause an increase in porosity and a subsequent decrease in density. This finally leads to the expansion of the lithic material (Audley 1921:209 cited in Ibid.). Then the rock will fracture or at least develop fissure lines. On the other hand, quartz can also fracture when cooling down after heating. This sort of FCR will have more cortical or surface damage such as pitting and this will yield another artifact commonly known as a potlid. If a rock is heated or cooled too quickly it will spall off in irregular segments.

Next it is important to know the context within which the burned rock was found. When recovered in large abundance, fire-cracked rock is typically associated with hearths and activities that took place around the hearth (e.g. roasting, steaming, sweatlodges, and potprops) (Akins 1985). As Barbetti stated,”Demonstrating that fire was used at an archaeological site is a two-step process. One must first find the evidence and show that fire was present. It is then necessary to demonstrate that it was associated with human activity” (1986:771). One of the most common causes of natural fire is lightening (Westbroek et al. 1993). Burnt tree stumps and brush fires seem to leave similar impressions as camp fires or hearths (Clark and Harris 1985; Bellomo 1993, 1994). One archaeologist performed actualistic studies of fire at FxJj 20 Main, Koobi Fora, Kenya (Bellomo 1993, 1994). He was particularly interested in recreating what happens in the ground during and after campfires, tree stump fires and grass fires. Using a combination of archaeomagnetic studies and several other studies which measure different aspects of sediment magentism, the archaeologist was able to test for any changes in the magnetic mineralogy from fires. His temperature data showed that campfires burn at higher temperatures than tree or grass fires (544). From this, he was able to deduce that sediments under such humanly-controlled fires (as campfires or hearths) would display a higher change in their magnetism. According to his temperature data, campfires could get as hot as 600oC and maintain a constant 400°C for 1.5-3 hours (533). Neither grass or tree stump fires came close to maintaining such temperatures. Additionally, Bellomo showed that in profile, camp fire and tree stump features were actually completely different (Ibid). Whereas multiple campfires (in one spot) burned a basin-like shape about 15cm below ground surface, the tree stump burned a hole straight into the substratum (Ibid.).

At Old Colchester, there were no hearth features identified but we have so much FCR it begs further questions. Additional site formation processes may provide answers. The features may be deflated or perhaps destroyed by historic bulldozing activity. My next installment will be about the difference between fire-cracked rock and thermal pretreatment of rock.


Barbetti, M. (1986). “Traces of Fire in the Archaeological Record Before One Million Years Ago?” Journal of Human Evolution 15: 771-781.

Bellomo, R. V. (1993). “A Methodological Approach for Identifying Archaeological Evidence of Fire Resulting from Human Activities.” Journal of Archaeological Science 20: 525-553.

Bellomo, R. V. (1994). “Methods of determining early hominid behavioral activities associated with the controlled use of fire at FxJj 20 Main, Koobi Fora, Kenya.” Journal of Human Evolution 27: 173-195.

Clark, J.D. and Harris, J.W.K. (1985) Fire and its roles in early hominid lifeways. The African Archaeological Review 3:3-27.

McDowell-Loudan, E. (1983) “Fire-Cracked Rock:Preliminary Experiments to Determin its Naturea and Significance in Archaeological Contexts. The Chesopiean 21(1):20-29.

Westbroek, P., M. J. Collins, et al. (1993). “World archaeology and global change:Did our ancestors ignite the Ice Age?” World Archaeology 25(1): 122-133.

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Meanwhile at Ash Grove…


Today, Dr. Don Linebaugh from the University of Maryland brought a group of students to Ash Grove in Tysons Corner. The students are from the Anthropology, Architecture, and Historic Preservation programs and surveyed the kitchen using 3D scanning technology.


Some of their work was decidedly less high tech. Detailed documentation of the oven inside the kitchen required students to literally climb into the feature.  In the future, hopefully the data can be processed and put online so people can walk through Fairfax County’s past, virtually.

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Bi-Weekly Update


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Members of CART gave papers today at the annual meeting of the Middle Atlantic Archaeological Conference.  Julie went first; here she is talking about her thesis site in Delaware. 

And here, Megan discusses the results at one location on the OCPP where CART found an 18th century foundation.

Great job, team!

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Opportunities at Mount Vernon

George Washington’s Mount Vernon has announced three new summer opportunities for current students or recent graduates.  Mount Vernon staff provided the following descriptions:

GIS Internship – A paid summer intern position related to both GIS and historic preservation, with the goal of creating a comprehensive geographical and temporal map of Washington’s original land holdings.  The internship could appeal to students from a wide range of academic backgrounds, but they must be proficient with GIS software.


Midwest Tool Collectors Association Historic Preservation Internship – A paid summer intern position to conduct research on Mount Vernon’s 1782 stable to prepare a restoration plan for this brick structure.  Experience with documenting historic resources and/or interest in 18th-century Chesapeake architectural history and material culture preferred.


2015 Collaborative Historic Preservation Field School – This credit course, offered through the University of Maryland, will instruct students in historic preservation method and theory. Students will learn archaeological and architectural field methodology including surveying, GIS, laboratory procedures, and current themes in historical archaeology and historical preservation.

Field School

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Biweekly – 6 March 2015


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