Lots of rock. As shown in this example, a close-up of site 41BR65 at
Camp Bowie, burned rock middens are made up of quantities of stones, broken
up from heating and no longer as useful for cooking. Dense accumulations
such as the midden pictured here represent mainly cooking debris discarded
from central baking pits.
Excavation shot showing Unit 1, Level 4 (40 cm below ground surface).
This excavation unit was placed at the outer edge of the midden to establish
depth and to determine if internal features were present.