Bone preservation in Hayonim Cave (Israel): A macroscopic and mineralogical study

Understanding the cause of patchy bone distributions in archaeological site s requires that one distinguish bone decomposition in place from 'empty' ar eas where bones were never present. Marked horizontal variations in bone ab undance are found in the thick Mousterian layer (E) of Hayonim Cave, a larg e Paleolithic site in northern Israel. Infra-red analyses of minerals in th e sediments identify zones of advanced diagenesis and decomposition alongsi de zones whose chemistry clearly favored the preservation of bones and wood ash. These differences adhere closely to the distribution of recognizable bones in the deposits, indicating that spatial variation in bones abundance is essentially a product of differential preservation conditions. However, the few bones present in the bone-poor units are in surprisingly good cond ition. The higher degree of abrasion damage and more random orientations of these bones indicate that small amounts of recent material were introduced into older layers by small burrowing animals and perhaps localized trampli ng. The ratio of post-Mousterian to Mousterian artifacts in layer E, and th e numeric contrasts in bone abundance among stratigraphic units, indicate t hat time-averaging from mechanical intrusion was quantitatively unimportant (2-5%) throughout this > 2.4 m thick layer. Our findings support Karkanas et al. (2000) suggestion that bone and ash mineral diagenesis in caves foll ow step-wise rather than gradual transformations in geological time. Good p reservation environments can be distinguished from poorer ones on the basis of mineral assemblages in sediments, and deposits that once contained bone and wood ash can be identified long after the visible traces of those mate rials have disappeared.