(View exact match)sievingCATEGORY: technique
DEFINITION: A technique of particle size analysis used to determine the size grades of pebble gravel, sand, and coarse silt in sediment and soils of archaeological deposits. The archaeologist processes all the earth from the site through a fine mesh, then does dry screening in a shaker frame or wet sieving with flowing water. It improves the recovery rate of artifacts. For lighter soils, dry sieving may be effective. Wet sieving is used for more claylike material and for recovering bones, shells, seeds, and other biological remains. The sieved residues are then dried and sorted by hand. The sample is placed on the top sieve of a series of nested sieves. Sieve mesh sizes are standardized. Wet sieving as part of a flotation technique is used to recover small remains from sites.wet sievingCATEGORY: technique
DEFINITION: A method used to separate organic material (seeds, snails, insects, etc.) from soil before drying, identification, and analysis. It is a more time-consuming method of extraction than flotation by machine, but has the advantage of being more accurate in its results since there is more control over extraction from the sample. The sample is poured into a sieve in a bowl of water, the lumps of soil are carefully broken up, and the organic material is trapped in the mesh while the soil particles are removed.
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dry screeningCATEGORY: technique
DEFINITION: The sieving of excavated soil and sediment through (usually) 1/4-inch mesh, to recover artifacts not found in excavation.fishbone analysisCATEGORY: technique
DEFINITION: The study of the remains of fish on archaeological sites, in the form of bones, otoliths, and scales. The latter only survive occasionally in anaerobic conditions, while otoliths have not, to date, been frequently recorded. Fish have markedly different skeletons from mammals. Many fishbones are so small that they appear only in sieving and the bones commonly preserved are the jaws and some other head bones, and the vertebrae. They usually accumulate in refuse deposits and may be interpreted in terms of diet and fishing on the site or in the area that supplied it. Identification of species through comparison with modern fishbones is becoming easier as larger collections of comparative material are built up. When a species has been identified it can lead to evidence for the hydrological conditions around the site; also, the occurrence of the remains of marine species on an inland site has implications for the movement of groups or a trade in fish. A combination of species identification and aging of fish through study of the otoliths can lead to assumptions about the seasonal occupation of certain settlement sites and the subsistence economy of the associated groups.flotationCATEGORY: technique
DEFINITION: A technique developed to assist in the recovery of plant, insect, and molluscan remains from archaeological deposits; a method of screening in which minute pieces of flora are separated from the soil by agitation with water. The technique works on the principle that organic material such as carbonized seeds, snail-shells, and beetle wing-cases have a lower specific gravity than inorganic materials such as soil and stone, and will thus float on the top of a suitable liquid medium while the rest will sink. Water is commonly used for flotation, though there are disadvantages since it has a fairly low specific gravity and heavier material such as fruit stones will sink. Other media have been used, such as carbon tetrachloride solution or zinc chloride solution. Flotation of samples by hand is called wet sieving. Samples of material are slowly poured into water, any lumps are broken up, and the flot is drawn off with a sieve. The method is more controlled than flotation by machine, and the recovery rate is better. For large-scale excavations, machines are used. Operating principles vary: samples are poured into a large container of water, or water and paraffin, which is agitated by air injection or by currents of inflowing water. The addition of a floculating agent increases surface tension, though not all machines are 'froth flotation' machines. The flot is carried off the surface through a mesh, or series of meshes to allow preliminary sorting. Samples retrieved are sent away for specialist identification and analysis by an archaeobotanist.grain impressionCATEGORY: artifact
DEFINITION: A cereal grain which has been incorporated by chance in an artifact, such as pottery, bricks, daub, etc. The impression left in the clay may be clear enough for identification to be possible and thus provide useful evidence on the crops in cultivation at the time. On firing, or as a result of decomposition of time, the organic material is lost but its outline remains, often in great detail. Casts of these impressions are taken using latex rubber, and the original plant or animal may be identified. Before the widespread sieving and flotation of deposits began to yield large amounts of environmental evidence, these grain impressions were an important method of getting information on farming practices.molluscan analysisCATEGORY: technique
DEFINITION: The analysis of molluscan remains, of both marine and land species, as part of the examination of the environment of man. A mollusk/mollusc is any of a large phylum (Mollusca) of invertebrate animals (as snails, clams, or squids) with a soft unsegmented body usually enclosed in a calcareous shell. Edible species yield information on the subsistence economy of certain groups; in most cases it is the shells which survive. The analysis of marine mollusks involves separation of the shells from the sample by wet sieving, and the identification of varieties. The occurrence of mounds of discarded shell debris in shell middens also allows for a clear understanding of the collecting patterns, seasonal use, and preferences of man in the marine region. Land snails are increasingly used as an adjunct to pollen and insect analysis in attempts to reconstruct past environments.otolithCATEGORY: fauna
DEFINITION: Small, dense calcareous concretions from the middle ear region of fish, quite commonly found on archaeological sites. Otoliths are species-distinctive, and can therefore be used for identification purposes in the analysis of fish remains from a site. They also grow in annual rings and can thus be used to age the fish and to indicate seasonal use of the site. Otoliths are normally recovered by wet sieving of deposits.particle size analysisSYNONYMS OR RELATED TERMS: particle-size analysis, size analysis, size-frequency analysis, grain size analysis
DEFINITION: A technique for analyzing the grain sizes of archaeological or geological sediments, used to discover the manner and process of their deposition. The technique also allows the accurate description of a deposit, and comparison with other sediments. There are several methods of particle size analysis. Dry sieving, the sifting of deposits through various sizes of mesh so that particles are grouped into sizes, is suitable for larger grains from pebbles to coarse sand. Light or electron microscopy is used for finer grains of sand, silt, and clay. Sedimentation, the counting of grains dispersed in liquid as they fall to the bottom of a container, is suitable for the finest grains of silt and clay. A combination of methods, is frequently used. The analysis may yield information on whether the deposit is wind- or water-borne, how much it has weathered, and to what extent it has been affected by man. Particles are classified into a number of size grades, normally under such headings as boulders, pebbles, stones, gravel, sand, silt, and clay; sand is often further subdivided. The mixture of particle size grades found in a material is known as the texture.