GIS stands for 'Geographical Information System'. A powerful computerised method of data analysis and presentation,
it is becoming an essential part of archaeological work, as well as many other areas of research, government and
GIS works by linking databases and maps. Any data which has a geographical location can be included in a GIS. The
locational details are entered into databases using co-ordinates; these are almost infinitely flexible in scale and
may cover areas as large as continents or as small as individual buildings or features on an excavation.
Environmental, geological, topographical and hydrological data are some of the other types of information which
can be entered in linked databases so that they can be easily compared and combined with archaeological data. The
GIS produces a series of 2- or 3-dimensional maps, the scale, angle and orientation of which can be altered
instantly by the user - it is possible to zoom in or out on individual data points to look at details or the wider
picture, or click through to another layer telling you different information. Data can be analysed statistically
and the results presented in map and graphic form. The two types of GIS software which are most popular at present
are ArcView and MapInfo.
An example of the value and utility of GIS might be in researching early lead mining sites in the North Pennines.
The known sites can be mapped onto geological data showing the likely areas for lead mining; each individual site
could be investigated by clicking through to progressively more detailed maps and plans. By widening the search,
new areas of archaeological interest may be identified where it is obvious that suitable geological conditions for
lead mining exist but there have been no systematic attempts at archaeological recording.
There are many potential uses for GIS. Archaeologists have created models of intervisibility between prehistoric
monuments such as barrows and hillforts, this is known as 'viewshed' analysis. Settlement and agriculture have
been mapped in relation to soil types, rainfall levels, flood zones and patterns of light and shadow caused by
hills and valleys. Although many researchers make use of GIS, it is also very suitable for recording and managing
information - most SMRs and NMRs are now either GIS-based or actively seeking to become so.
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