A STUDY OF PREHISTORIC BURNED ROCK MIDDENS IN WEST CENTRAL TEXAS

Burned rock middens large accumulations of thermally fractured rock are among the most common features in Archaic archaeolgical sites in Central Texas. With a sample of 1654 archaeological sites, the distribution of burned rock midden sites is compared with the occurrence of live oak savanna in an area of approximately 55,800 square kilometers in west central Texas. The objective of this distributional analysis is a preliminary assessment of the hypothesis that burned rock middens relate to prehistoric exploitation of acorns. The similarity of the distribution of burned rock middens to both the modern and postulated Archaic distribution of live oak savanna supports this hypothesis. On this basis, it is Inferred that acorns from Quercus fusiformis and perhaps Q. texana and Q. sinuata, var. breviloba were major foods during at least part of the Archaic period. Burned rock middens are suggested to be accumulations mainly of discarded boiling stone fragments broken from use in stone-boiling of acorn foods. Data on modern areas of live oak savanna are used to show that the acorn production Is quite substantial in some portions of Central Texas and is sufficient in most years to support a population density of 1-3 persons per square kilometer for at least half a year. The implications of this potential are evaluated, especially in regard to the kinds of archaeological remains found at burned rock midden sites. The similarity of the distributions of burned rock middens and live oak savanna suggest that the modern general occurrence of live oak savanna is little changed from that 5000 years ago. The possible loss of oaks in one portion of the study area may reflect either short or long periods of drying conditions at some time since 5000 BP