Sydney - Shopping, letter-writing, sex, music composition: there's not much you can't do on the computer these days.

Even archaeology.

Without leaving his Melbourne office, Australian David Thomas has become a world expert on the historical sites of Afghanistan's Registan Valley.

The La Trobe University researcher has pinpointed 450 sites that may have been well known to the Ghurid people in the 12th century. He's got not only the coordinates for forts, camp sites, reservoirs, dams, villages and farms but pictures as well.

Google Earth, a free service available on any modern computer, provided all the information.

It's time-consuming: it took nine hours in front of a computer monitor to find likely significant sites in one 17-square-kilometre block. But, compared with dodging roadside bombs laid by the Taliban and the bullets of their adversaries, it's safe.

Afghanistan has been just about off-limits to western archaeologists since the 1979 Soviet invasion. Their local counterparts fare better and Thomas passes on likely locations of historical sites.

"The most valuable aspect of what we are doing is that we can pass on the information to the Institute of Archaeology in Afghanistan," he said. "Then it's a question of whether they can travel there and have the resources to investigate further."

Thomas said the satellite imagery available on Google Earth was accurate. He used football fields and other sites with fixed measurements to make sure his measurements for forts and other installations were correct. (dpa)