In the late 1980s, images from a space shuttle and Landsat satellites found a spiderweb of thin lines converging to a point in the middle of the Arabian Desert. Legend had it that Ubar -- an ancient city long lost to the blazing, windswept sand -- once provided refuge to travelers moving along the frankincense trade route that snaked through the vast wilderness.

Although people tried to find Ubar for centuries, the city remained as mysterious as Atlantis. But the lines seen in the Landsat images were too organized to have appeared naturally. They seemed to suggest the existence of a man-made structure, such as a cemetery or a city. In 1990, archaeologists arrived at the site and began digging. Eventually, their excavation uncovered the walls of what many now believe is the lost city of Ubar.

Without geoarchaeology, Ubar might have remained hidden forever. This more modern version of archaeology incorporates the tools, techniques and knowledge of various earth science disciplines, such as geology, geophysics, geography and sedimentology. In some circles, this combination of old- and new-school techniques is nothing more than the evolution of classic archaeology. Other circles have heralded this approach as a new scientific discipline -- geoarchaeology. Either way, as a unique field or a subdiscipline of archaeology, geoarchaeology has emerged as an exciting and interesting area of study.

Here's one major reason why: It reduces our reliance on chance discoveries about human history. For ages, serendipity has played a major role in how archaeologists came to know about a site of historical significance. For example, a construction or quarry project would turn up ancient soil and the material remains it held. Once the site was known, archaeologists showed up, shovel and trowel in hand, and started digging. They sifted the dirt and collected artifacts that provided clues of ancient human activity. They paid little attention to the soil deposits, which they scooped, scraped away and removed in buckets. Instead they focused intently on the artifacts and features of the site being explored.

Geoarchaeologists are just as interested in uncovering the story of past human activity, but their methods differ. The soil itself holds their interest as much as anything buried in it. They record changes in soil texture, color, density and smell. Sometimes they don't even dig at all, choosing instead to look at satellite images or data from seismic readings, which was what led them to Ubar.

Keep reading to find out what other tricks geoarchaeologists have up their dusty, khaki sleeves.