How Science Unlocks the Secrets of the Past

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How science unlocks the secrets of the part ARCHAEOLOGY was born in sixteenth-century Europe as an offshoot of the scholarly pleasures of the Renaissance. Many early archaeologists were collectors motivated by an aesthetic interest in Antiquity and a desire to reconstitute the background of events described by ancient writers.

Until the beginning of the twentieth century, generations of archaeologists set out to rediscover an excavate great sites, to record the evolution of styles and to retrace the interplay of cultural influences according to aesthetic criteria and typology--the study of objects by types.

Today's archaeologist usually lives in a world which is far from the preoccupations of scholarly collectors or prestige excavations. He or she is at the centre of a group of specialists from different scientific disciplines. Working with these specialists and profiting from methods used in the natural sciences, modern archaeologists attempt to decipher the messages stored in the material archives of human activity in the form of multifarious traces left on a wide variety of materials. Although they may not tread in the footsteps of Schliemann at Troy and Mycenae, or those of Lord Carnarvon in egypt, nor experience the excitement of idscovering tombs overflowing with precious objects and jewellery, they perform an equally valid humanist task as they use the latest scientific techniques to recapture aspects of the life, environment, landscape, economy or technology of the past.

To excavate is to destroy, and once destroyed the archaeological heritage--unlike nature--cannot grow again. These seemingly commonplace observations underlie the mission of the archaeologist, who must identify the slightest hint of past human activity, analyse every facet of the information it can yield by using every available method, and evaluate his or her interpretation through reasoning which may later be tested with the computer.

The following text, with accompanying boxes and illustrations, attempts to provide a highly simplified and selective account of some of the complex scientific techniques being used today by archaeologists in prospection, excavation, analysis, dating and preservation.

WHERE TO EXCAVATE. One problem a field archaeologist faces is that of knowing where to dig. Sometimes the study of old documents and literature is helpful: in other cases clues must be found from the air or on the ground. The use of aerial photography in archaeology (see page 18) goes back to the beginning of the century, when photos were taken from a balloon above Ostia, the port of Rome. Its systematic application has made it possible to study the layout of towns before beginning to excavate, to locate traces of Roman roads and villas and observe systems of land management. More recently teledetection from satellites has vastly expanded the scale of possibilities for aerial prospection.

On the ground, the use of electrical resistivity to detect buried walls and ditches is now widespread. In making a resistivity survey, an electrical current is passed through the ground to measure the resistance of the soil, which is affected by moisture. Metal detectors are being widely used by treasure hunters in some countries where, when used indiscriminately and irresponsibly, they have caused havoc to the archaeological heritage. Recently US and Swedish technicians have developed a radar-truck capable of recording structures buried to a depth of four metres in certain terrain such as peat.

EXCAVATION. When they come to excavate, the most important method used by modern archaeologists is to study the stratigraphy of a site, the arrangement of archaeological deposits in superimposed layers or strata. The earliest excavations at Rome in the sixteenth century and a at Pompei and Herculaneum in 1717 were above all a harvest of objects from the soil, and Schliemann himself admitted that he had dug through (and destroyed) many recent levels before reaching the "interesting" Trojan levels. …