April 1, 2026: Bite Sized Artifacts

By Miranda Leclerc

April 1, 2026

Paper presented at the Middle Atlantic Archaeological Conference in Gettysburg, VA, March 11-15.

The quotes below are just a sample of entries from the account books of Thomas Jefferson, his wife Martha Jefferson, and their granddaughter Anne Cary Randolph (pulled from Thomas Jefferson's Memorandum Book, Figure 1). Each recorded numerous transactions with enslaved people at Monticello- the 5,000-acre home and plantation of President Thomas Jefferson and four hundred enslaved men, women, and children. This documentary record provides insight into a market where enslaved people could own the value of their labor – a freedom otherwise denied under bondage.

Pd. Old Toby for 1 doz. Chickens (Thomas Jefferson, July 15, 1769)

Bought 15 chickens from old Jenny…pd for with bacon (Martha Jefferson, June 1777)

Paid J. Hemmings 4 doz eggs. 4 [s.] 6 [d.] (Anne Cary Randolph, Sep. 1, 1805)

Sales of fowl, eggs, and vegetables underpinned the local plantation economy (Sawyer & J. Bowen 2012; Library of Congress, n.d.). Enslaved people hunted wild game and raised domesticated poultry in yards around quarters (Figure 2). The meat and eggs acquired from these birds supplemented insufficient rations and were a source of income for enslaved and free workers. However, archaeological excavations of domestic sites have not yet revealed evidence of animal pens or coops, possibly due to the temporary nature of these structures (Sawyer & J. Bowen 2012; Thomas Jefferson Foundation n.d.a; Thomas Jefferson Foundation n.d.b; O’Connor 2021). Additionally, differential preservation of animal remains has resulted in a lacking “varied and well-represented avian faunal” across several Monticello sites (Crader 1984, 555) . Therefore, we must look elsewhere in the archaeological record. 

A gastrolith is an object ingested by a bird that aids digestion in the gizzard, also known as grit or gizzard stones (Figure 3). During 2025, archaeologists recovered and cataloged more than 100 gastroliths from Monticello’s East Lawn. While poor avian faunal preservation seems par for the course at Monticello, the gastrolith sample size from the East Lawn is unprecedented. This paper is a case study of the relationship between gastrolith and faunal deposition, testing strategies for joint analysis of gastrolith and faunal assemblages to craft a more complete understanding of animals and diet at Monticello. 

Research questions include:

1. What is a gastrolith?
2. What can we learn about diet and animal husbandry at Monticello through gastroliths, especially on archaeological sites where faunal preservation is poor?
3. How do the East Lawn faunal and gastrolith assemblages illustrate changing land use over time?

Introduction to the Mountaintop East Lawn Excavations

In 2025, Monticello Archaeologists excavated five-foot by five-foot quadrats on the East Lawn to mitigate construction of an ADA pathway (Figure 4). The East Lawn is a part of the Monticello mountaintop, the nucleus of Thomas Jefferson’s home farm and plantation. It sits south of the main house and north of Mulberry Row, a 1,000-foot-long street with industrial workshops and quarters for free and enslaved workers. To the west of the excavation site are additional quarters and workspaces in the South Wing, including the 1809 kitchen. 

The East Lawn is a product of two massive leveling events which created the artificial mountaintop. The first was in 1768, when Jefferson contracted enslaved workers to level a 250-foot square. The new topography served as the basis for Monticello I. During this time, tobacco was the primary crop of the agricultural plantation and construction of the first Monticello main house, a Palladian mansion, was ongoing. By 1796, economic and environmental factors motivated a switch from tobacco to wheat cultivation. In a second leveling event, workers expand the leveled mountaintop landscape, and Jefferson redesigns the main house to the Neoclassical structure which stands today (Neiman 2008; Armstrong et al. 2025).

Most quadrats were excavated to a depth of 1.5 ft, with several excavated deeper or to subsoil for research purposes (see Figure 5). Artifacts were collected from a ¼ inch dry screen. As of February 2026, over 140,000 artifacts from the Mountaintop Access East Lawn project have been cataloged into the Digital Archaeological Archive of Comparative Slavery (DAACS). Artifact processing is ongoing.

102 of the artifacts are gastroliths. 1,425 are animal bones weighing a total of 1,085.9 g (see Figure 6a-b). Despite the East Lawn having the largest quantity of gastroliths from any dry screened archaeological site at Monticello, no bird bones have been identified by catalogers. The identifiable faunal is overwhelmingly spongy mammal bone. The faunal assemblage has not been analyzed by a zooarchaeologist at this time.

Understanding Gastroliths

While birds are the subject of this paper, they are not the only animals who produce gastroliths. Depending on site and context, archaeologists have interpreted gastroliths as game pieces, stone tools, and charms or spiritual objects (Goode 2009; Handler 2009; Schroeder & Greer 2019; Wilkie 2000; Heath & Breen 2009; Russell 1997). They can indicate animal pens, yards, bird burials, and butchering (Conrad 2020; Lyle 2014; Taber et al 2019; Kaktins 2015; Heite et al. 1995; Arthur, 1971; Brooks et al. 2012; O’Connor & Neiman 2022). Within the scope of this paper, a gastrolith is defined as an object consumed by a bird to aid digestion of food in the gizzard (Gionfriddo & Best 1996; Lyle 2014; Taber et al. 2019; Wings 2007; Wings & Sander 2007; DAACS 2018).

The mechanics of a bird’s gastrointestinal system are important to investigate the trajectory of how an object becomes a gastrolith, and how a gastrolith becomes an artifact (Figure 7). A bird first swallows the object while grazing. Food and water are stored in the crop, a pouch in the esophagus, until moving into the proventriculus. The proventriculus is the glandular stomach, where hydrochloric acid begins breaking down food. 

Mechanical digestion occurs in the ventriculus, or gizzard. This is where the gastroliths, also referred to as grit, function similarly to teeth. Strong muscle contractions of the gizzard and abrasive qualities of gastroliths work together to break down tough food like insects and grains. This grinding also erodes the gastrolith, producing smooth edges and polished surfaces. Lastly, the pyloric fold connects the gizzard to the small intestine and regulates passage between the two organs. Only once materials are digested to a small enough size can they pass through the fold and eventually be excreted (Gelis 2007; R.  Bowen n.d.; Jacob & Pescatore 2013; Wings 2012).

East Lawn Gastrolith Assemblage

There are 96 ceramic, 5 stone, and 1 olive green glass gastroliths in the East Lawn assemblage (see Figure 8). Of the ceramic gastroliths, 1 is whiteware, 58 are unidentifiable refined earthenware, 1 is pearlware, 2 are porcellaneous, 26 are unidentifiable porcelain, 7 are Chinese porcelain, and 1 is unidentifiable coarse earthenware (see Figure 9). Many have unidentified ware types because digestion obscures attributes, such as decoration, glaze, and paste.

14 ceramics retained underglaze decoration, including transferprint, handpainted, and slip on refined earthenwares (Figure 10). The pearlware has blue transferprint, and the whiteware has purple transferprint. All seven Chinese porcelain gastroliths had handpainted blue decoration, including one which is a rim to a Chinese porcelain plate (Figure 11). The strong presence of discarded household goods indicates that the birds in this assemblage were domesticated.

Stone gastroliths are more difficult to identify, especially at unscreened sites. Under magnification with a Dino-Lite (Figure 12), a gastrolith can be distinguished from environmentally worn pebbles (Schroeder & Greer 2019; Brooks et al 2012). Lateral movement of the gizzard creates a unique pattern of pitting and rilles, or grooves, on the surface of gizzard stones (Whittle & Onorato 2000). The survival of stone gastroliths is also dependent on the material's resistance to stomach acids. In an ostrich gizzard, limestone may be dissolved in as quickly as 24 hours, but quartz remains over a year (Wings & Sander 2007). 

Two stone gastroliths are arkose, two are slate, and one is an unidentified metamorphic rock (Figure 13). Slate and arkose are both architectural materials transported to the mountaintop (Figure 14). Arkose was quarried from a rock outcrop at the base of Mountain to construct the Monticello I and Monticello II main houses (Neiman 2025). For a bird to have consumed and retained arkose pebbles in their gizzard, they must have had access to these architectural materials. Furthermore, of nine stone gastroliths recovered from all screened and unscreened sites at Monticello, arkose gastroliths were only identified in the East Lawn assemblage. Therefore, the location of where the bird or birds which ingested these stone gastroliths lived can be narrowed down to the Monticello mountaintop. 

How did the gastroliths get to the East Lawn?

Size analysis helps determine the processes behind gastrolith deposition. The smallest East Lawn gastrolith is an 8.4mm glass fragment, and the largest is a 20 mm ceramic (Figure 15). The most frequent gastrolith size is 15 mm (Figure 16). One cause of gastrolith deposition is excretion with fecal matter. This only occurs after digestion decreases the grit to such a size that it passes through the pyloric valve.  

In a study of 3-week-old layer chickens, the average excreted quartz grit size was 1.08mm (Takasaki and Kobayashi 2020, see Figure 17). From an experiment on 10 captured mallard ducks, around 18% (43 of 237) gastroliths in fecal matter measured greater than 3.35 mm in length (Trost 1981).

In a separate study on ostriches, less than 1% of excreted stone gastroliths exceeded a length of 4mm (Wings 2012, see Figure 18, left). Under the statistically proven premise that gastrolith size increases with body size, it is possible to infer that the average 15mm East Lawn gastrolith could not have been excreted- even by the largest of birds (Gionfriddo & Best 1996; Best & Gionfriddo 1991; Wings & Sander 2007). 

Therefore, we must explore the possibly that the gastroliths deposited on the East Lawn never left the gizzard through natural processes. In a Crow Canyon Archaeological Center study of 21 turkey burials, the largest gastrolith measured 15.4 mm. Burials provide unique insight as the animal remains, including gizzards, are intact. Male turkey gizzards contained an average of 270 gastroliths, only 19 of which were large enough to be recovered in a ¼ field screen (Lyle 2014). The Savannah River Archaeological Research Program analyzed gastroliths from the Flamingo Bay Site, concluding that gastroliths between 7 mm and 12 mm of size were from the butchering and consumption of large waterfowl or turkey-sized birds. The authors also report that a ¼ inch screen was not adequate in recovering a representative gastrolith sample, particularly duck gastroliths (Brooks et al. 2012). Similarly, Ferry Farm has estimated the size of historic birds by comparing gastroliths to modern turkey gizzard stones (Kaktins 2015, see also Figure 18, right). 

In studies of non-archaeological gizzard grit, the average size of a Canada Goose gastrolith extracted from within the gizzard is a length of 2.02 mm and width of 1.52 mm (VerCauteren et al. 2003). The largest gastrolith from the gizzards of a Sandhill Crane was 17.4 mm and of Mute Swans and Tundra Swans, 14 mm (Franson et al. 2001). Altogether, these studies show great variability in gastrolith size as well as note the influence of season, diet, and size or color preference on a bird’s grit consumption. 

Nonetheless, comparative data of gastrolith sizes from other archaeological sites and modern studies all support the hypothesis that the East Lawn gastroliths are products of bird butchering, which was not an infrequent event on the mountaintop. 

Martha Jefferson records bird purchases and killings, most often goose, duck, and chicken, in her account book (Figure 19). Each is an event resulting in the removal and cleaning of a bird’s gizzard, and with it, the gastroliths too large to be passed. 

However, it is also evident that these 15mm gastroliths are but a limited sample of the largest of gastroliths from large birds (Figure 20). Future archaeological research should collect flotation samples from areas of suspected animal butchering to recover gastroliths smaller than ¼ inch. 

How can the faunal assemblage help our analysis of diet?

Next, gastroliths can be placed in conversation with faunal for a more holistic analysis of diet. Weight is used as the unit of measurement to account for variation in bone fragmentation and gastrolith material (Figure 20). We estimate the time of deposition through BlueMCD, a mean ceramic date where ceramic types with tighter known manufacturing ranges are weighted (Figure 21). Contexts with less than three dateable ceramics are removed from this analysis. To measure changes in deposition over time, I further aggregated artifacts into 5-year periods by BlueMCD. Peaks in gastrolith weight indicate greater discard of poultry butchering waste, and for faunal, greater discard of the predominately mammal animal bone. Between the years of 1785 and 1834, gastrolith and faunal weights increase and decrease at the same times, albeit at different rates.

We can dive deeper into why gastroliths and faunal peak at different moments by calculating gastrolith proportion (Figure 22). This measures how much of the total butchering assemblage, defined as the combined weight of gastroliths and faunal, is comprised of gastroliths. Jefferson-period poultry consumption occurs in the largest proportion between 1805 and 1819. The initial increase in gastrolith proportion coincides with the 1796 transition to Monticello II, thus, the shift from tobacco to wheat cultivation. 

Under the new agricultural regime, enslaved people had more time to hunt and tend to livestock. This resulted in greater quantities of independently procured wild or domesticated fowl in diets and on the market, as enslaved people on Mulberry Row both consumed more birds and sold more birds to the Jeffersons. It is a significant result that gastrolith data reflects this pattern. Significantly, faunal analysis of buildings r, s, and t on Mulberry Row, enslaved households, and the East Kitchen yard, the Jefferson household, also showed increased chicken, turkey, duck, and goose in diets after 1790 (Sawyer & Bowen 2012, see Figure 23).  This proves that despite size biases and collection methods, gastroliths can be used to effectively measure dietary change in the absence of avian faunal. 

How can spatial data help us understand workspaces on the mountaintop?

Finally, gastrolith distribution shows changing locations of workspaces and ornamental landscapes on the Mountaintop. Figure 24a shows the location of quadrats in the Mountaintop Access East Lawn project by Northing and Easting. Each point shown in Figure 24b-c is scaled to the total amount of faunal or gastroliths present across all contexts in that quadrat.

There are three major deposit types in the stratigraphy of the East Lawn: A-Horizon or present-day topsoil, plowzone, and landscaping fill. 9 gastroliths are from A-horizon, 70 are from plowzone, and 22 are from landscaping fill. One gastrolith was in utility pipe trench fill cut through plowzone (Figures 25-26). 

Artifacts date the landscaping fill contexts to the c.1790s leveling event, which expanded the East and West Lawns and accommodated construction of the North and South Wings. Monticello II landscaping fill covers the entirety of the project area. Artifacts in landscaping could have been transported in source deposits of the fill or mixed in during or after leveling. Geoprobe cores and excavations found fill may include architectural rubble, and redeposited subsoil, topsoil, and B or C horizons from elsewhere on the mountaintop (Armstrong et al. 2025; Monaghan 2010). 

Unlike landscaping fill, plowzone does not cover the entire project area and disappears to the north and east. Plowzone contains a mix of 18th and 19th century artifacts, including those that post-date the Jefferson-period (Figure 27). The latest TPQ for a plowzone context containing a gastrolith is 1840, with a BlueMCD of 1845. After Thomas Jefferson’s 1826 death and the 1827 dispersal sale, Uriah Phillips Levy, a naval officer from New York, bought Monticello. Between 1832 and 1923, three generations of the Levy family, including Uriah’s mother and nephew, intermittently lived at Monticello and initiated the first restoration effort. Overseers, enslaved, and free workers lived at Monticello and maintained the property Thomas Jefferson Foundation n.d.c; Thomas Jefferson Foundation n.d.d). Ongoing research suggests that the plowzone is a result of bushhogging and land clearing during the Levy period. One gastrolith definitively dates to the Levy occupation; a purple transferprinted whiteware produced between 1829 and 1867 (Maryland Archaeological Conservation Lab 2015).

Even 7 of the 8 A-Horizon contexts with a gastrolith and dateable ceramics have BlueMCDs between 1791 and 1819. These contexts cluster in the north of the project site, often where A-Horizons seal Monticello II landscaping fill (see Figure 24). Despite time averaging from decades of landscape shaping and plowing, BlueMCDs can help date the vast majority of these gastroliths to the Jefferson period. 

When comparing gastrolith and faunal distribution across site, the southwest area stands out as a location where both gastroliths and faunal cluster. These are 9 units associated with the privy vent, a 150-foot-long air shaft that ventilates an indoor privy in the main house (Figure 28). Jefferson instructed the beginning of privy vent tunnel construction in December 1799. It was built in a builder’s trench cutting through landscaping fill, meaning the leveling of the East Lawn was completed before privy vent construction began (O’Connor 2025). 

Gastroliths and faunal are found in the builder’s trench backfill, landscaping fill, and plowzone above and around the privy vent. Monticello II and builder’s trench fill contexts have BlueMCDs between 1760 and 1799. Even ceramic dates from plowzone contexts above the privy vent tunnel average well within the Jefferson period, with the latest BlueMCD being 1824. This is evidence that gastroliths and faunal were deposited on the East Lawn after leveling and privy vent tunnel construction concluded. Excavators also noted contexts with charcoal flecking and flat lying artifacts which sealed landscaping fill and privy vent backfill. 

These observations establish the southeast East Lawn as a site of butchering waste discard and food preparation, the source of these artifacts is likely being the 1809 kitchen. With the completion of Monticello II construction, the kitchen for the main house moved from the South Pavilion into the South Wing. The kitchen yard, a work area where food was prepared and kitchen waste discarded, moved eastward as well (Figure 29). 

Archaeological excavations of the East Kitchen Yard in the 1980s and 1990s located three postholes, interpreted as a possible coop or pen for kept animals (Sawyer 2012). In 1813, Thomas Jefferson wrote a letter describing his shephard dogs which, quote, “drive up the chickens, ducks, turkies every one into their own house.” Perhaps these three postholes are traces of one of these houses. This function of the southwest East Lawn as an extension of the East Kitchen Yard contrasts the northern area. Here, oval garden beds frame the east facade of Monticello. The distribution of butchering waste emphasizes the permeability between ornamental and functional working spaces, enslaved workers’ adaptive use of the mountaintop, and the realization of the landscape. 

Conclusion

This paper set out to explore the analytical value of gastroliths at an archaeological site. While they are commonly understood to indicate bird butchering, a deeper analysis of Monticello’s East Lawn revealed a significant data-backed relationship between gastrolith and faunal deposition. Gastroliths do have analytical limits. They are not an appropriate substitute for avian faunal when identifying species or number of specimens. However, this paper has demonstrated areas where gastrolith analysis can be pushed further: identifying bird domestication- even location of kept animals- and measuring the makeup of diet at a site over time. 

Furthermore, birds had a role in sculpting economic freedom of enslaved and free workers on the plantation. This market was not unregulated. Thomas Jefferson wrote to Thomas Mann Randolph with instructions to “confine them [enslaved people] to such articles as are not raised for the farm. There is no other way of drawing a line between what is theirs & mine” (1798). Likewise, Jefferson stipulated in an undated overseer’s contract “not allowed to keep a horse or a goose” (n.d). This is later amended in 1809, when he offers an overseer the “the priviledge of keeping geese and Turkeys” under conditions of profit sharing and keeping the animals in agricultural fields (T. Jefferson & T. Randolph). Birds were mobile features of the landscape across the Monticello Plantation, and gastroliths offer unique insight into daily life and the exercise of property ownership by its residents. I look forward to continuing research on this subject. 

Acknowledgements

I would like to thank our lab team (Corey Sattes, Chris Devine, and Iris Puryear), our field team (Crystal O'Connor, Mia, Armstrong, Ellie Alvey, Alyssa Baker, Kyle Koch, Chris Lin, Jack McFadden, Lizzie Prow, and Josie Schreiber), as well as Fraser Neiman and Derek Wheeler.

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