Stone Soup

Contributed by Ryan Wheeler

I’ve been interested in indirect cooking technology since the early 1990s when I worked with archaeologists Barbara Purdy and Ray McGee in an excavation of an Archaic period site in central Florida where we found evidence of this ancient American Indian culinary technique. At the site, submerged beneath the waters of Lake Monroe and not too far from Orlando, in levels pre-dating ceramic pottery, we found fragments of fired-clay objects. Ray and I were fascinated by the shapes—balls, patties, cylinders, and biconical forms—and speculated about their purpose. They were similar to clay and stone objects found at other early sites and thought to be used in a variety of indirect cooking, either for boiling or steaming. Ray ultimately studied the clay objects for his 1994 University of Florida master’s thesis, which combined aspects of experimental archaeology and materials science. I was lucky enough to be around to help with his study, which began with replicas of the Lake Monroe clay objects. We dug clay from near the site, it was processed to remove impurities, and used to make numerous clay object replicas, which were then subject to extensive experimental trials. Ray demonstrated that not only could the clay objects be used for boiling, but that the different shapes had different thermal properties. And, not only did the clay objects survive successive heating and drenching cycles, the objects fragmented to closely match the fragments we had found in archaeological deposits. Thousands of years before the first pottery was made and used in the Southeastern United States, the clay ball chefs understood how to manipulate clay into ceramic objects and the distinct differences between shapes with greater and lesser surface area and other details. In a final experiment Ray and I tried to cook with the clay objects, heating water in wooden bowls to boil shrimp and corn meal. The meal was successful!

Image of fired-clay objects used in cooking experiment.
Several shapes of fired-clay cooking objects: balls, patties, biconical forms, and cylinders.

During spring term 2017 I’ve been fortunate to mentor a senior independent research project, or IP. The student’s spring project is a continuation of a project begun in winter term, which investigates ancient pottery making technology, with a particular focus on temper—additives to clay that help with making pottery vessels, firing survivability, and use life after firing. I shared Ray McGee’s thesis with the IP student, who was equally fascinated by the clay objects and their use in cooking. Much of the student IP focused on collecting and using native clay sourced from West Newbury, MA, and then experimenting with firing vessels made using a variety of traditional tempers, including sand, crushed shell, and decomposed granite, as well as untempered clay. The almost innumerable variables have presented some real challenges, but also open a tiny window into pottery making thousands of years ago. We agreed too that part of the project this spring would include making, firing, and using replicas of the fired-clay objects, using the varying tempers and shapes described above. An article in Indian Country Today indicates that hot stones were used by American Indians in the Northeast in both steaming pits and boiling.

Our attempt today to use the fired-clay objects in boiling followed much like the experiment that Ray McGee and I conducted during his thesis research in the early 1990s. The clay objects had been prepared, dried, and pit fired several weeks earlier. We noted that the cylinder-shaped objects were rather delicate, and many of the objects had small cracks. In general, the ball and biconical forms were intact, while the patties had more cracks. A supply of the fired-clay objects were added to a small oak wood fire, which quickly climbed in temperature, ultimately leveling off around 1500 degrees Fahrenheit. After objects had been in the fire a small number were cycled through a wooden bowl containing about a quart of water. The water temperature rose quickly, though it got a bit murky from charcoal. We decided that we had the capability to boil water. We prepared a fresh bowl of water and corn meal grits—three cups of water and one cup of grits—as directed by the package. We cycled fired-clay objects in and out of the bowl until the water was absorbed and the grits were cooked—about five minutes. A little salt and butter made the grits a tasty treat. Next we replicated the experiment with about half a pound of shell-on shrimp. More water was used and by this point we had become more proficient at cycling the clay objects from the fire to the bowl and back. The water boiled and shrimp were quickly cooked. Lemon and butter completed this course. For the most part the clay objects were holding up, though more of the cylinders broke and some of the patty shapes also cracked and split in the fire. Some broke while they were in the wooden bowl. The ball and biconical shapes seemed to hold up the best and were perhaps best suited to our purpose—getting the water boiling quickly. After the shrimp, we were a bit more ambitious and agreed to try a handful of spaghetti pasta. This would be a real test, since the water would have to boil continuously for 9 to 10 minutes. We added more clay objects to the fire, recognizing that we might need more to keep the water going. Quickly cycling the clay objects in and out of the fire produced a rolling boil that easily cooked the noodles. Our wooden bowl, however, suffered, and we had two pretty substantial cracks that developed on either side. Adding more water and fewer cooking objects may have helped—it seemed like 2 or 3 at a time in the wooden bowl were enough to keep the boil going.

Image of Phillips Academy senior cooking with fired-clay objects.
Phillips Academy senior adding heated fired-clay objects to his cooking pot.

Data crunching and correlating is ongoing in this student project, and at least one additional outdoor firing is planned in order to test a few additional variables and observations gleaned from experiment and research. The fired-clay cooking objects, however, are evidence of indirect cooking in antiquity, long before the creation of pottery vessels. It’s not clear if fired-clay cooking objects were made and used in the Northeast in the long distant past, and the more recent accounts mention cooking with hot stones. Pottery was adopted in the Northeast around 3,000 years ago, perhaps introduced from neighboring areas. In Florida and other parts of the Southeast, pottery is much older—made and used at least 5,000 years ago—and appears to be an in situ development. Perhaps the fired-clay cooking objects were precursors of pottery and gave people insights into manipulating clay and the properties of fired-clay. As this student project has demonstrated, making pottery by hand and firing it in the open air presents considerable challenges that could only be overcome with significant knowledge of clay, temper, fuel, weather conditions, and more.

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