Sediment Analysis of a Prehistoric Rockshelter: The Abri Pataud

Abstract

Rockshelter 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.

Quantitative sourcing of slackwater deposits at Boila rockshelter: A record of lateglacial flooding and Paleolithic settlement in the Pindus Mountains, Northwest Greece

“…Whatever their depositional or stratigraphic context, information on the source of the fine sediments can provide valuable paleoenvironmental information (e.g., Mandel and Simmons, 1997;Woodward, 1997b;Courty and Vallverdu, this issue). To date, however, studies incorporating data on the provenance of rockshelter sediments have commonly involved only qualitative or semiquantitative estimates of sediment source components based on lithological or mineralogical analyses (Farrand, 1975;Woodward, 1997b), particle size characteristics (Woodward, 1997a), or micromorphological observations (Goldberg, 1992;Karkanas, 1999). Cornwall (1958) was one of the first researchers to recognize the value of establishing the origin of cave and rockshelter sediments as a means of elucidating site formation processes.…”

Stratigraphy and geoarchaeology of the Red Canyon Rockshelter, Crook County, Wyoming

“…Although many detailed geoarcheological studies of rockshelters and rockshelter sediments exist (Farrand, 1975;Laville, 1976;Laville et al, 1980), almost all of these studies focus on solution features developed in carbonate rocks. Studies of sandstone shelters, in con-trast, are relatively rare (Styles et al, 1983;Donahue and Adovasio, 1990).…”

“…Although a good deal of geomorphic and geoarchaeological research has addressed the rockshelter environment, most detailed studies have focused on rockshelters developed in calcareous rocks (Farrand, 1975;Laville, 1976;Laville et al, 1980); sandstone rockshelters have received relatively little attention (Donahue and Adovasio, 1990). This article describes the stratigraphy and development of a sandstone rockshelter site, 48CK1395, in the northeastern margin of the Black Hills, Crook County, northwestern Wyoming (Figure 1).…”

Sand traps for the unwary - problems in the interpretation of sedimentological analyses

“…It is usually measured by shaking a known weight of sediment, from which the silt and clay fractions have been removed by washing, through a series of graduated Endecott sieves for a stated time and weighing the amount of sediment resting on each sieve (Gale and Hoare 199 1 :3 1-7). In rockshelter deposits, the gravel fraction is frequently not subdivided because the quantities of sediment needed to obtain an adequate sample of each clast size are prohibitively large (Farrand 1975(Farrand , 1979. However, unless the proportion of silt and clay in a sediment has been calculated the deposit from which they came has not been fully characterised and its origin and mode of deposition may remain obscure.…”

“…Schmid 1958;Rosenfeld 1964;Farrand 1975Farrand , 1979Tankard and Schweitzer 1976;Webb 1980;Butzer 1981;Stein and Farrand 1985), which is being continually added to, particularly in the pages of the journal Geoarchaeology. This literature is not confined to European and North American studies; some excellent work has also been done in Australia (Frank 197 1 ;Shackley 1978;Hughes 1980).…”