Petra (Jordanie) :Archaeologists use satellites to discover enormous monument

John-Michael Schneider |

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Petra new discovery 3 ngsversion 1465412587544 adapt 536 1The monumental platform in the ancient city of Petra, created as a layered composite image with architectural measurements shown. - I. LaBianca

Archaeologists have discovered a massive monumental structure at the ancient city of Petra in southern Jordan.

According to a study in the Bulletin of the American Schools of Oriental Research, even after two centuries of fieldwork at Petra, the monument was hiding in plain sight.

Thanks to high-resolution satellite imagery and pictures from aerial drones, archaeologists Sarah Parcak, a National Geographic fellow, and Christopher Tuttle, executive director of the Council of American Overseas Research Centers, were able to locate and identify a small 8.5-by-8.5-metre building resting on a much larger platform roughly the length of an Olympic swimming pool.

Screen shot 2016 06 09 at 10 44 58 amA composite image showing the layering of a drone image on top of satellite photos. The rectangular mound is the new site discovered by archaeologists Sarah Parcak and Christopher Tuttle. - I. LaBianca

Parcak and Tuttle have been strong advocates of “archaeology from space” and using aerial photography to help locate old structures that are difficult to detect with the naked eye.

Just because a previous survey claims it visited an area does not mean that everything was found, especially prior to the use of satellite data,” they noted. “One can easily miss small bumps and ridges on the ground that may connect when seen in aerial imagery.”

The ancient city of Petra was once occupied by the Nabatean people, a group of settlers in the Southern Levant from around 500 B.C. to 300 A.D., and most of the uncovered monuments were constructed during the latter half of the city’s existence.

One of those monuments, a sandstone-pillared temple called Al Khazneh, popularized by films like Indiana Jones and the Last Crusade, has become one of the most iconic structures at Petra. The 2,500-year-old city in present-day Jordan was labeled a UNESCO World Heritage Site in 1985 and attracts roughly half a million tourists every year.

Screen shot 2016 06 09 at 9 54 48 amArchaeologist Christopher Tuttle standing at the southwest corner of the interior, smaller platform, looking north. At ground level, it can be difficult to see the pattern of stones forming a rectangular monument at Petra. Q. Tweiss

Pottery samples from the newly discovered monument date back to the mid-second century B.C., possibly making it the first structure discovered from the city’s early years.

The large platform is unlike anything found there so far, and the open area combined with the position of the site relative to the city has prompted further questions from the researchers who are eager to excavate the structure.

This monumental platform has no parallels at Petra or in its hinterlands at present,” the researchers wrote. “The unique platform design and location raise a number of intriguing questions regarding its functions over time throughout the life of the ancient city.”

The study argues that the larger 56- by 49-metre platform was initially used for ceremonial purposes. The smaller building, aligned east-west on the platform, could also have been converted to a Christian chapel during the Byzantine Era because early Christians faced east while praying; or, during the city’s later Islamic period, it may have been used for more practical purposes like processing grain.

Satellite archaeology graphic 565x611A diagram showing the satellite imaging process used by archaeologist Sarah Parcak in a previous study. A similar process was used to locate the monument at Petra - Sarah Parcak and Gregory Mumford

Petra Archaeological Park encompasses about 264 square kilometres, but the city’s centre only covers about 6 square kilometres. Now that the researchers have shown how satellites can be used to locate archaeological structures from above, they are excited about possible future discoveries.

In 2011, relying on similar satellite techniques, Parcak and her team identified 17 potential buried pyramids and roughly a thousand tombs across Egypt.

Parcak and Tuttle concluded their recent study on an optimistic note:

Given the discoveries at Petra, satellite imagery analysis has much to offer other archaeological projects, especially at well-known sites with similar environmental conditions, where new and surprising discoveries continue to make headlines.”