Sediment Analysis of a Prehistoric Rockshelter: The Abri Pataud

Abstract

AbstractRockshelter and cave-mouth deposits accumulate in specialized niches through the breakdown of the enclosing bedrock, the addition of windblown and fluvial sediment and, in the case of prehistoric sites, human habitation debris. Certain modifications of routine sediment analysis are necessary in order to realize the full potential of paleoenvironmental interpretation. These sediments are coarse, necessitating the collection of large samples, commonly 10–20 kg. The size and shape of the coarse fraction yields information on rockfalls, freeze-thaw activity, and weathering effects. Travertine and soil-carbonate coatings on the rock fragments indicate variations in ambient humidity and soil formation, respectively. Studies of the granulometry, mineralogy, and geochemistry of the fine fraction lead to conclusions concerning primarily the postdepositional modification of the sediments. Heavy minerals can be important in determining the provenience of the fine sediment. These methods of analysis are discussed in detail with the Abri Pataud as a specific example, and caution is urged in making regional generalizations from the study of a single site.