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Plateaus and Canyonlands Main
Prehistoric Texas Main

Cooking with Granite

Artist's depiction ofa camp scene with women adding rocks to an earth oven
Women add rocks to an earth oven that will be used to bake roots in this artist's depiction of a camp scene. Painting by Charles Shaw.
Inspecting an outcropping of granite pegmatite near the site. Photo by Chuck Hixson.
Inspecting an outcropping of granite pegmatite near the site. Photo by Chuck Hixson.

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One of many hearths at the rancheria, likely used for cooking. Photo by Chuck Hixson.
One of many hearths at the rancheria, likely used for cooking. Photo by Chuck Hixson.
Burned rock midden at the site. Photo by Chuck Hixson.
Burned rock midden at the site. Photo by Chuck Hixson.
Central pit in midden, with large rocks lining interior. Photo by Gene Schaffner.
Central pit in midden, with large rocks lining interior. Photo by Gene Schaffner.
Typical terrain and vegetation around the Graham-Applegate site. Photo by Chuck Hixson.
Prickly pear cactus grows abundantly in the site area, to the dismay of investigators working there. Photo by Chuck Hixson.

The people who lived at the Graham-Applegate rancheria were great consumers of granite rock; they brought many tons of it into the settlement from isolated outcrops in the surrounding area. Some of the rocks went into the construction of the houses, providing material for the wall supports and central hearths, but by far the greatest amount of rock was used in the cooking of food. Most rocks when heated in a fire absorb and store heat. Long after the fire has died down, the rocks continue to release the heat, making them ideal heating elements for different kinds of stone-age cooking "appliances." In prehistoric times, the people of central Texas made full use of this kind of cooking technology, constructing stone hearths in many different shapes and sizes. Most interestingly, they constructed earth ovens—layered arrangements of hot rocks and food placed in shallow pits and capped by a thick layer of earth. These were used to cook many kinds of foods but particularly certain plant foods that require long cooking before they are edible or their full nutritional value is realized. When the rocks cracked into small pieces from repeated heatings, they were tossed out and the oven pits re-lined with new rocks. The huge mounds of fire-cracked rocks, or burned rock "middens," that built up over time around these often inconspicuous ovens have long confounded archeologists.

Virtually all the cooking features—hearths and ovens—that have been studied in central Texas were constructed of limestone rocks. The Edwards Plateau that dominates the region is made up of Cretaceous limestone and was the only rock available in most places. However, this is not the case at the Graham-Applegate site. Millions of years ago, erosion removed a portion of the Cretaceous limestone on the northeastern part of the Plateau, exposing a 2500-square-mile region of ancient metamorphic and igneous rock known today as the Llano Uplift. The Graham-Applegate rancheria is located in the southeastern part of the Llano Uplift in an area of granite bedrock. In the immediate area of the site, the granite near the surface has weathered into small gravel-size fragments, except for thin horizontal seams (known as pegmatites) of more consolidated feldspar and quartz rock. Along the nearby arroyos where the pegmatite seams are exposed, ancient people could have gathered rocks large enough for their building and cooking purposes.

The rancheria people constructed dozens of small, flat circular hearths on which they grilled or roasted different kinds of foods. Unfortunately, with the exception of mussel shells, few food remains have survived in the sandy, gravelly soils at the site. Scores of these shells have been found scattered about the area, particularly around the small hearths on which they were cooked. Mussels were probably collected from the Llano River a half-mile (0.8 km) away. Considering the large numbers of arrow points found at Graham-Applegate, animal foods must have been very important but the direct evidence is no longer there: even bones do not last long in the ground in the site area.

The single largest feature at the rancheria is the earth oven and its surrounding pile of fire-cracked rock (burned rock midden) that dominates the southwestern corner of the site. While burned rock middens of limestone rock are common on the Plateau, very few granite middens have been recorded by archeologists in the Llano Uplift. Why this is so is not yet clear; perhaps earth ovens were only rarely constructed of granite because they made inferior heating elements, although recent experiments do not seem to bear this out. Granite takes and holds heat well but breaks apart after only one or two uses. Limestone, in contrast, can sometimes be reheated five or more times before breaking. Perhaps granitic burned rock middens are more difficult to detect on the Llano Uplift because of the soil and topographic conditions there.

The midden at Graham-Applegate went unnoticed until a test pit was excavated over it. Almost 30 feet across and nearly 2 feet thick, the burned rock midden at the Graham-Applegate rancheria contains perhaps as much as 20 tons of burned rock, representing many oven firings and subsequent cleanings. Few food remains were found in the burned rock debris surrounding the oven; there were a few small fragments of a large, deer-sized animal, mussel shells both large and small, and a small amount of charred plant material. The central area of the midden contains traces of numerous pits dug out over time for ovens. These pits were probably lined with large granite boulders. The soil in the interior is almost black from the many fires that burned there. Outside the midden area the soil is a light tan but, closer to the center, it becomes more and more stained by carbon. Evidence from other sites indicates these ovens were constructed to bake certain plant foods for long periods of time. Just what was cooked at the rancheria is not yet known, although we have some ideas. Sotol, an important food that was baked by aboriginal people in earth ovens, does not grow in large numbers (if at all) in the sandy soils of the Llano Uplift. A related species, a kind of narrow-leaf yucca, however, does; the edible parts include the emerging flower stalk available in late spring and the green seed pods that develop a little later in the year. Both yucca and sotol could be baked in earth ovens.

Today, the site is covered by dense stands of prickly pear cactus, much to the consternation of the crew—especially those who don't watch their step. Ranching in recent times has no doubt encouraged its spread but this plant was certainly present in the Llano Uplift in the Late Prehistoric. The green, pad-like stems, or nopales, were a reliable food source as were the fruit or tunas when ripe in late summer. If the rancheria was occupied primarily in winter, nopales would have been available for earth-oven baking; if the stay was extended into spring, wild onions and yucca stems would have been an abundant food source for the rancheria dwellers.


Granite rock from the Llano Uplift area, such as that used by the rancheria people for constructing earth ovens and small fires. Photo by Chuck Hixson.
Granite rock from the Llano Uplift area, such as that used by the rancheria people for constructing earth ovens and small fires. Photo by Chuck Hixson.
Exposure of granite pegmatite, where rancheria folk likely gathered stones for use at their village. Photo by Chuck Hixson.
Exposure of granite pegmatite, where rancheria folk likely gathered stones for use at their village. Photo by Chuck Hixson.
Hearth used by later Austin phase visitors to the site. Photo by Chuck Hixson.
Hearth used by later Austin phase visitors to the site. Photo by Chuck Hixson.
Close-up view of midden and its dense accumulation of fire-cracked rock. Photo by Chuck Hixson.
Close-up view of midden and its dense accumulation of fire-cracked rock. Photo by Chuck Hixson.
Soil samples from midden area, showing light-colored, unstained soil from outside midden (left) and darker, increasingly carbon-stained samples taken from within midden and central pit. Photo by Gene Schaffner.
Soil samples from midden area, showing light-colored, unstained soil from outside midden (left) and darker, increasingly carbon-stained samples taken from within midden and central pit. Photo by Gene Schaffner.