Archaeological glossary
	A-D E-K L-R S-Z Abbey Although we might think of any large monastery (see below) as an abbey and a nunnery as something else, the word 'abbey' actually refers to any large religious community (and its buildings) – whether lived in by monks or nuns – and ruled over by an abbot (a word originally meaning 'father') or abbess. The second-in-command in an abbey was the prior, so any monastery dependent on a larger, more important one was usually known as a priory. ^top Aerial photography Because earthworks can be so confusing on the ground, many archaeological sites have been found through aerial photography. Even if earthworks have been ploughed over, it is still possible to identify sites through scatters of stones, tiles and other debris, or through cropmarks (see below). Aerial photography is also splendid for putting a site into context. Ancient field boundaries can suddenly become obvious, as can the strips of fields tilled centuries ago. Trackways and other features unseen on the ground can appear crystal clear on an aerial photograph. ^top Anaerobic conditions 'Anaerobic' means 'without air'. In such conditions – such as waterlogging – where there is insufficient oxygen for bacterial and fungal growth, the normal rotting processes do not take place. So all the things made of wood, leather, straw and so on that archaeologists love to find – but which, in our climate, usually rot away very quickly – remain well preserved. Much can be learned from such evidence about the lives of ordinary people in the past; many of the objects they used and the structures and buildings in which they lived were made of wood. But such objects are a nightmare for the people who have to conserve them, since they have to stop these objects from rotting once they are brought into normal – that is, aerobic ('with air') – conditions. ^top Augering This is a technique used by environmental archaeologists to look at deposits below ground without having to dig trenches, writes Jane Siddell of the Museum of London Archaeological Service. In this, it is similar to geophysical prospection. Augering consists of driving a probe into the ground and collecting a sequence of soils and sediments within the probe. This can be done by hand with a small auger or with a mechanised version. The probe is then removed and the contents examined to see what type of environment – marshy, for example – is represented in that area of land. The depth of drilling is accurately measured, and along with the Ordnance Survey co-ordinates, the results can be located in three dimensions. The results can then be used in conjunction with historical surveys and geophysical plots, for instance. The technique is quick and can cover large areas to examine how the sub-surface horizons change within the wider landscape – for example, to search for ancient courses of rivers and streams. It may also be used to locate specific horizons such as burnt layers. ^top Bones, identification of The identification of bones – both human and animal – from archaeological sites can tell us a great deal. First, researchers must work out which bones they are and from which species they come. Once this has been done – and it's a very skilled job – some idea can be gained not only of species being hunted or farmed at the time and the butchery techniques and selection of joints preferred, but also of the wild animals in the area. The examination of human bones can lead to a greater understanding of the population's range of diet, and the deficiencies and diseases (but only those that affect bones) with which they were afflicted. ^top Coins To an archaeologist, coins are invaluable as prime dating material. When they were produced – minted – is usually known; indeed, many of them were issued to commemorate certain events or were dated in some other way. Obviously a coin found on a site can only date from the earliest time that that particular coin became available. If it is in 'mint' condition, the layer of an excavation in which it was found may be of the same date as the coin. However, if the coin is well worn, it may well have been deposited (lost or buried) some time after it was produced. Thus, all the other things found with or around the coin can be roughly dated. ^top Context A vague term used by archaeologists to describe the position of a particular find or site in relation to other things. In fact, the context of a find or feature is of prime importance since it is only when its relationship to others is understood that some progress can be made in the investigation of a site. This is why objects removed by looting – 'treasure hunting' and raids by 'night hawks' (individuals with metal detectors who don't reveal what they have found or where they have found it) – are of less value to archaeology in terms of the information they can give than those objects that are carefully recorded as they are excavated. Out of the context in which they existed in the ground – including all the other earlier, later and contemporary features, objects and deposits – they can only be appreciated as single unrelated items. ^top Cropmarks These are light and dark marks visible – particularly in aerial photographs (see above) – in growing and ripening crops, which reflect differences in the subsoil beneath. As crops, especially cereals, come to maturity, any parts that are short of water (because they are growing over, say, hidden stone walls or packed stone layers) will tend to grow less and ripen first, while areas of crops over pits and ditches will tend to remain greener a bit longer and be taller than the rest. These differently growing plants can, together, sometimes become ghostly outlines of former houses, barns and other structures, as well as ponds, walls and wells. However, cropmarks can also be caused by the natural geology of the site, the weather at the time the crop was sown and/or is growing, and numerous other non-archaeological factors. ^top Dendrochronology Dendrochronology or 'tree-ring dating' makes use of the annual pattern of growth shown by most tree species in temperate regions. Each year trees such as oak put on a layer of new wood under the bark. The thickness of that layer – the tree-ring – will depend on various factors. The genetic make-up of the tree and the type of soil in which it is rooted both play a role, as do other environmental factors, but generally it is the climate that determines if the ring will be wide [conditions favourable for growth] or narrow [unfavourable conditions] ... Therefore, examination of the annual growth rings of a tree will reveal not only its age, but also the fluctuating climatic conditions during its lifetime. Trees of the same species growing at the same time in the same general area will show similar trends in tree-ring growth ... To make use of the information contained in tree-rings, long tree-ring chronologies have been constructed ... The Northern Ireland chronology, for example, goes back to 5452 BC, while a German sequence from the Rhine area extends back to 8480 BC ... [In England] there is now a continuous sequence that runs from the present back to AD 404, and another ... covering 434 BC-AD 315 ... No English tree-ring sequence has been found that spans the 4th century AD. [Adapted from Dendrochronology: Guidelines on producing and interpreting dendrochronological dates, English Heritage] ^top Earthworks Mounds, hollows, banks and ditches made of earth, clay and soil, often representing collapsed structures. ^top Environmental archaeology Using seeds, pollen, snails, beetles and other insects, bones and so on to reconstruct what the environment might have looked like in the past. Most specialists who deal with this sort of evidence come from the nearest related sciences – botany, zoology and ecology. A particularly interesting and exciting form of archaeology, it attempts to put the settlements and sites of past periods into context, enabling us to see what the countryside and towns were like for earlier people, by using information on the sorts of crops they grew (and weeds they endured) and the wild and domesticated animals they used for food. ^top Field survey and investigation All human activities leave some imprint on the land, writes Stewart Ainsworth. Some are obvious, such as castles and cathedrals, some – such as hedges, fields and earthworks – less so. The role of the archaeological investigator is to identify the clues and traces left by the obvious to help find and understand the less obvious. Evidence can come from many sources – maps, documents, aerial photographs – but mainly through looking at the ground itself and principally earthworks ('lumps and bumps'). These are the clues on the surface to what is below ground and tell us how landscapes evolved. By acquiring a wide knowledge of what archaeological monuments look like, the archaeological investigator can survey 'lumps and bumps', compare them to known sites and interpret them to reveal and understand the sites and landscapes built by and lived in by our ancestors. ^top Fieldwalking An area or a site is divided into a grid, and fieldwalkers then move slowly through their assigned parts of it, picking up everything of interest from the surface – for instance, pottery sherds, beads, bits of glass, pieces of bone. These finds will tell the archaeologist a number of things. Remains of various ages may indicate that the site was occupied at different times and, if the remains are from different cultures, by different types of societies. If the density of finds decreases or simply stops, this can be a clue to the location of the site's boundaries. The accuracy of fieldwalking can be affected by the state of the land. Ploughing can bring older finds to the surface. Erosion of steep terrains can lead to finds being buried much deeper than they should be or to them being washed away from their point of origin. And if a site has been occupied by a number of societies over time, it can be very difficult to discover evidence of the earlier ones among the greater number of finds from the later ones. ^top Geophysics A group of techniques that are used to find sites (and parts of sites) without excavation. They include magnetometry, resistivity and ground-penetrating radar, all of which are explained below. ^top Ground-penetrating radar Electromagnetic waves, writes John Gater of GBS Prospection, are transmitted into the ground and are reflected back to the surface when they 'hit' different layers of soil, tarmac, concrete or rock. The time taken to 'bounce' back gives an idea of the depth of the layers and provides a detailed picture of the buried deposits through a vertical slice of ground. 'Lumps and bumps' See Field survey and investigation ^top Magnetometry Archaeologists, writes John Gater, use instruments known as fluxgate gradiometers to measure minute anomalies in the Earth's magnetic field. These can result from the past activities of humans on an archaeological site and may indicate the position of buried pits, ditches, pottery kilns and areas of metalworking. ^top Maps Modern maps, whether on paper or drawn by computer programs, are essential in plotting out all the details of archaeological work so that a record can be kept and the interrelationships between features can be appreciated. Old maps – particularly those that show the countryside in detail and record field and placenames – are of immense help in the locating of sites and in explaining what many of the things found during excavation and field survey actually were. ^top Monastery Any religious establishment where the people in it follow a 'rule', such as that of St Benedict (the 'Benedictines'), and have taken vows. Abbeys, priories, nunneries and friaries are all sorts of monasteries. ^top Post hole Many early buildings and other structures were made of wood, and before the use of stone foundations, their main supports were usually posts set in the ground. To construct these, a hole was dug, the timber was set in, then the hole was filled with a packing of stone or earth. From these holes and the packing around them, archaeologists can recognise the sites of such posts and therefore of the building or other structure that they once supported, even when the posts themselves have rotted away or were removed. ^top Pottery Of all the things that archaeologists could study, pottery is, perhaps surprisingly, by far the most useful. This is because of the main properties of the fired clay from which it is made. Once fired, pottery is very resistant to destruction, and even after being buried for thousands of years or knocked about in the ploughsoil for generations, bits and pieces – known to archaeologists as 'sherds' – of these vessels can still be found. They were originally just thrown out of houses on to the surrounding land or dumped into a rubbish pit (midden) or taken along with the rest of the domestic debris out to the fields in the manure. Because of developing technology in manufacture and the types and degrees of decoration, styles of pottery have constantly changed. Thus even small individual sherds can be recognised and some idea of their date and context can be guessed at. Finding them may also indicate whether a site is present but hidden beneath the ground, and give some idea of its date. Priory See Abbey, Monastery ^top Radiocarbon dating This method of dating organic materials found by archaeologists – for example, bone, antler, peat, marine and freshwater shells, wood and charcoal – depends on the fact that plants take up carbon dioxide gas from the atmosphere and incorporate it into their tissues. Some of that carbon dioxide contains the radioactive isotope of carbon: carbon 14 (C14). When it dies, a plant ceases to take up C14 from the atmosphere and that already taken up decays at a known rate, allowing the time that has elapsed since the plant died to be measured. Animals and humans that eat the plant tissues take the C14 into their own bodies and so their remains can be similarly dated. After 120,000 years, so little C14 is left that it is difficult to get accurate results. ^top Resistivity survey By injecting small electrical currents into the ground and measuring its resistance to the current flow, writes John Gater, it is possible to gain an idea of where buried wall foundations, floors, paths and roads are surviving. While these deposits result in high resistance readings, waterlogged ditches and pits will produce low resistance anomalies. ^top Seismic refraction This is used widely in exploration geophysics, writes Sue Overton of GBS Prospection, but only has limited application in archaeology because of the relatively shallow depths involved. However, its strength lies in the fact that it does provide information about how deep an archaeological feature or deposit might be. The technique involves using a sledge hammer or a small explosive charge to emit a compressional energy wave into the ground. As this wave passes through the subsurface, there will be distinct changes in its velocity as it passes through different layers. At each interface, some energy will return to the surface. The time it takes for this energy to travel from the surface into the ground and back again is recorded by a line of sensors called geophones. This enables us to provide a vertical section through the earth. In this sense, the technique is similar to ground-penetrating radar (GPR; see above). However, while GPR is of limited use on 'wet' sites such as clay, seismic survey is best suited to such conditions. ^top Stratigraphy A 'section' cut through a site – like a layer cake with a slice removed – can give a detailed look at the history of that specific area. This can range from the geology at the bottom, up through the layers that result from construction and occupation, with recutting of ditches, replacement of walls and the like, to the abandonment of the site and, at the top, the formation of soil with turf. The objects associated with the layers of a section – especially pottery and coins – can give good evidence of the date of occupation of the site. However, the depth at which finds are unearthed may not determine their age. This becomes clear when a site's stratigraphy – the order and relative positions of different layers (strata) in the soil – is studied, since various features (for instance, graves, walls and ditches) can cut through older layers. ^top