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Somerset Levels
DEFINITION: Low-lying wetland region of Somerset in southwest England, famous for the preservation of remains in peat. Ancient trackways have been revealed and, with techniques such as pollen analysis and radiocarbon dating, it has been possible to establish the sequence of human and climatic development in the area. Permanent settlement occurred only on small 'islands' raised above the level of the marsh (e.g. the Iron Age villages of Glastonbury and Meare), but wooden tracks crossed the wet areas. The earliest discovered is the Sweet track dated to the Neolithic c 3600/2800 BC; after that tracks continued to be built at various times in the 3rd millennium BC. There was a long hiatus in track construction, perhaps because drier conditions made them unnecessary, but with climatic deterioration in the Late Bronze Age there was a new phase of track construction c 900-450 BC (alternatively, c 1100-500 BC).
arbitrary level
CATEGORY: technique
DEFINITION: In an excavation, the basic vertical subdivision of an excavation unit, defined metrically, such as in 5-, 10-, or 20-centimeter levels. These levels are prescribed when natural layers of stratification are lacking or not easily recognizable.
dumpy level
DEFINITION: A surveyor's level composed of a short telescope fixed rigidly to a horizontally rotating table and a spirit level.
CATEGORY: tool; term
DEFINITION: An instrument used in surveying which takes vertical measurements and which is much used in excavation for the recording of site contours and accurate depths of features, especially for making maps and identifying the location of artifacts. There are several types of leveling instrument, the Y or dumpy level, the tilting level, and the self-leveling level. Each consists of a telescope fitted with a spirit level and, generally, mounted on a tripod. It is used in conjunction with a graduated rod placed at the point to be measured and sighted through the telescope. The theodolite (q.v.), or transit, is used to measure horizontal and vertical angles; it may be used also for leveling. The differences between the types are in the ease of leveling: the first has a single spirit level for the whole instrument, the second a separate spirit level for spindle and telescope with a tilting mechanism and adjustable screw on the telescope, and the third an optical part operated by a pendulum so that the line of sight is always horizontal. Having established a datum point, the instrument is sighted on a leveling staff or rod which is marked in a graduated scale, metric, or imperial. The difference in level between the telescope and the base of the rod can be read off on this scale, and the result subtracted from the height of the level itself above ground; the final figure gives the real height, or depth, of the feature above or below the ground at instrument point. Subtracting the stadia rod reading from the height of the level above the ground surface gives the difference in height between ground surface at the instrument station and the ground surface at the datum point. A series of levels taken across a site will give contours, while excavated features and small finds can be leveled in with greater accuracy than with tapes from a hypothetical ground surface. The term is also used to refer to the actual height measurements taken with such an instrument. More generally, archaeologists often use the term 'level' interchangeably with layer. In excavations the remains are divided into levels that contain the buildings and objects belonging to a phase.
level bag
DEFINITION: A, usually paper, sack containing archaeological objects from a single horizontal level within a single excavation square. Finds are usually grouped by type (by artifact classes, bones, plant remains, charcoal) and put into labeled (plastic) bags inside the level bag.
level record
DEFINITION: Written record completed for each level in each excavation unit, providing detailed information on how a given level was excavated and what was found in it.
CATEGORY: technique
DEFINITION: To establish the height above the site datum of a number of points (spot heights) which will either record the level of the surface of a feature or layer, or enable a contour survey to be constructed. It also means to find the heights of different points in (a piece of land) esp. with a surveyor's level.
line level
DEFINITION: A small spirit-bubble designed for suspension from a string; often used to lay in horizontal lines across an archaeological site. It is not as accurate as transit-defined vertical provenience.
natural level
SYNONYMS OR RELATED TERMS: stratigraphic level
DEFINITION: Excavation units corresponding to levels defined by stratigraphy, as opposed to arbitrary levels. Strata removed according to their human or geologic disposition.
sea level
CATEGORY: geography
DEFINITION: The level of the surface of the sea; position of the air-sea interface, to which all terrestrial elevations and submarine depths are referred. Changes in the volume of water held in the sea and relative movements of the land surface, resulting from various types of deformation of the earth's crust are important in archaeology. Sea-level fluctuations are shown by deposits and landforms on the coasts of localities. The sea level constantly changes at every locality with the changes in tides, atmospheric pressure, and wind conditions. Longer-term changes in sea level are influenced by the Earth's changing climates. The sea level appears to have been very close to its present position 35,000 years ago.
significance level
CATEGORY: measure
DEFINITION: The probability of a type I error or willingness to reject a true hypothesis.
stratigraphic level
DEFINITION: Strata removed according to its human or geologic disposition.
subsistence level
DEFINITION: The minimum resources, e.g., food, shelter, water, necessary to support human life.
trophic levels
DEFINITION: Levels within the food chain characterized by similar energy consumption. A trophic level is a step in a food chain of an ecosystem. The organisms of a chain are classified based on their feeding behavior: 1) the producers, green plants; 2) the herbivores, or plant eaters; 3) primary carnivores, or meat eaters, which eat the herbivores; and 4) secondary carnivores which eat the primary carnivores.

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