Archaeology is being revolutionised by remote-scanning techniques that use airborne lasers to detect otherwise invisible ground features. This 'light detection and ranging' technology, known as LIDAR, helps scientists record differences in altitude down to just a few centimetres. Trees and bushes are no obstacle - they can be calculated out later with a computer. The lasers can even make out structures up to 4 metres under water. What remains is a 3-dimensional image of the earth's surface, including geometric formations that betray structures hidden underground.
     Archaeologists in Germany have already discovered thousands of new sites. For decades, researchers have been studying the Glauberg, in the central state of Hesse, where people settled some 7,000 years ago. Over the millennia, the plateau was inhabited by Celts and Alemanni. In 1996, archaeologists made the sensational discovery of an almost perfectly preserved statue of a Celtic warrior, now known as the Celtic Prince of Glauberg.
     It was thought unlikely that the mound would yield any more big surprises... until an airplane flew over it multiple times, sending pulses of light to the ground and measuring their echoes. The researchers were fairly stunned. At first glance, they recognised around a dozen potential burial mounds that they hadn't known about before. "We went and took a closer look at five of them," says Axel Posluschny. "They were all burial mounds."
     Posluschny manages Archaeolandscapes Europe (ArcLand), a 5-year project which began in 2010 in which some 57 European universities and research centres are participating, to increase the archaeological use of modern remote-sensing technology such as LIDAR, ground-penetrating radar and other electric and magnetic techniques.
     The broad potential of remote-sensing technology has been highlighted in recent years.
     A team with the 'Discovery Programme' research project in Ireland scanned the already heavily researched Boyne Valley with lasers, finding a number of previously unknown small mounds, possible burial tombs, and Stone Age earthworks.
     In a obscure forest near Goppingen in southwest Germany, an entire system of fortifications have been found. "The wall was 3 to 4 metres high at some points," says Jorg Bofinger, from the Stuttgart-based office of historical preservation. "It was completely unknown."
     In a roughly 2,000-square-kilometre area of the southern Black Forest, some 3,000 archaeological sites were known. Says Bofinger: "after the LIDAR scan, we had more than 36,000 sites."

Edited from Spiegel Online International (27 July 2012)