Researchers in the UAE say they have uncovered mysteries from the nation's past using radar technology at an archaeological site.
The possible presence of undiscovered underground structures was detected at the Saruq Al Hadid site in Dubai. The details are already published online by a team from Khalifa University in Abu Dhabi.
The structures at the location, which is close to the border with Abu Dhabi at the edge of the Rub' Al Khali, also known as the Empty Quarter, could be walls or hearths, although excavations will be needed to confirm this.
Showcasing the power of high-tech methods to reveal the past, the work has also highlighted hundreds of other potential objects beneath the surface, possibly including swords, axe heads and even golden snakes.
"Our latest study integrates ground-penetrating radar, radiometric data, and findings from previous expeditions to refine the chronology and extent of occupation at this remarkable site," said Dr Diana Francis, an assistant professor and head of the Environment and Geophysical Sciences (Engeos) laboratory at Khalifa University in Abu Dhabi.
Saruq Al Hadid, whose name roughly translates as "Way of Iron", is one of the most significant archaeological sites in the UAE.
It was occupied from the Umm An Nar period, which began in around 2600 BCE, through to about 1000 BCE in the Iron Age, when copper and bronze were smelted. Smelting also occurred during the subsequent Islamic period.
Ground-penetrating radar involves sending out pulses of microwaves (a type of radio wave) and analysing how the signals are reflected by structures below the surface.
The magnetic surveying, using a device called a magnetometer, detects anomalies underground, such as areas like fireplaces enriched with minerals, as well as objects made from iron or even clay.
"They are very efficient methods and non-invasive methods to indicate where subsequent excavations should take place," Dr Francis said.
In the study, the researchers describe how the surveys helped to characterise an area of the site called SAR53, which measures 340 metres by 150 metres. Some excavations have previously taken place in this area.
Five main underground structures were detected, some stretching for tens of metres, although their precise identification would require detailed excavations.
The researchers think that the data could indicate the presence of walls and supporting pillars. Other objects, the researchers wrote, "could be very thin metallic elements, such as swords".
The ground-penetrating radar also identified hundreds of "anomalies" that could represent objects buried between 20cm and three metres below the surface.
"These anomalies could be metallic or golden objects, such as swords, axeheads, golden snakes, or non-metallic objects, likely could include archaeological pottery and large jars," the researchers wrote.
Golden snakes are among the archaeological objects previously excavated from Saruq Al Hadid, which has its own museum near Dubai Creek.
The magnetic data too highlighted anomalies, which the researchers said could include artefacts such as copper items and ingots (blocks of metal).
Dr Francis said that the study provided "an exceptional record" of the site's stratigraphy or the layers of remains.
These layers are thought to represent the Umm An Nar archaeological period, which ran from 2600 to 2000 BCE, the Wadi Suq period, from 2000 to 1600 BCE, the Iron Age, from 1000 to 800 BCE, and the post-Iron Age. The site was occupied across all these periods.
Now that the ground-penetrating radar and magnetic surveys have revealed the likely presence of underground structures and objects, Dr Francis said that more work was needed to gain a full understanding of what lies beneath the surface.
"To confirm the remote sensing results, we need to wait for the manual excavation where the extent and exact nature of these structures will be exposed and their relative importance assessed," she said.
Another study by the same team of researchers, released last month in Archaeological Prospection and analysing a different part of Saruq Al Hadid, also found several possible large structures and smaller objects, highlighting the extent to which the site has many riches yet to be unearthed.