 urban archaeology is a sub discipline of archaeology specialising in the material past of towns and cities where long-term human habitation has often left a rich record of the past. humans produce waste: large concentrations of humans produce large concentrations of waste. kitchen waste, broken objects, and similar material all need to be disposed of. small numbers of people can dispose of their waste locally without encouraging vermin or endangering their health. once people began to live together in large numbers, around five thousand years ago, such methods began to become impractical. material would be brought into the these new settlements but would rarely be taken out again.  up until the nineteenth century when organised rubbish disposal became widespread in urban areas people invariably threw their waste from their windows or buried it in their gardens. if their houses fell down, a common enough occurrence when planning laws were non-existent, owners would pick out what they could reuse, stamp down the remains and rebuild on the old site. the effect of this is that even a moderately sized settlement of any antiquity is built on top of a heap of refuse and demolished buildings and is therefore raised up from its original height on a plateau of archaeology. this is most apparent in the tel sites of the near east where towns that have been occupied for thousands of years are raised up many metres above the surrounding landscape. in walled towns such as those in medieval europe the effect of the encircling defences was to hold in the waste so that it could not slip outwards, magnifying the effect. ==historic development== archaeological excavation within historic cities therefore often produces a thick stratigraphy dating back to the original foundation and telling the story of its history. the city of london for example, sits on a tel which preserves a layer of dark material attributed to the burning of the city by boudica in 60 ad. the dense stratigraphy of such cities posed problems for the archaeologists who first excavated them. earlier excavations were generally limited to rural areas, or towns which had been long abandoned. open area excavation was feasible as there was plenty of space and the archaeology could often be exposed just in plan. in working cities however, space for excavation is usually limited to the size of the open plot and one layer of archaeology needs to be excavated before the next one can be exposed. issues such as this had appeared before, at pompeii or at multiphase rural sites but the move towards the investigation of cities, which began in europe following the second world war when bomb damage left areas open for investigation, meant that there was a necessity in finding a new method of excavating. ==methods== the resulting solut
Archaeological_sub-disciplines