Village in Morocco is built on 4,500-year-old rock avalanche
For more than a century, geologists have been puzzled by the giant pile of boulders that sit underneath the village of Arroumd in the High Atlas of Morocco. However, according to a report in Live Science , new research has solved the mystery by revealing that the source of the boulders is an ancient rock avalanche that took place more than four millennia ago.
Previous theories have suggested that the geological features of Arroumd were caused by masses of rock and sediment being carried and deposited by glaciers. However, a new study published in the Geological Society of America Bulletin has suggested that this was not the case.
Scientists from the University of Manchester in England studied the rocks around the village of Arroumd, which sits below a cliff face 6,500 feet (2000 metres) high, and is the largest debris field known in North Africa. Their results revealed that the boulders had come tumbling down the cliff-face 4,500 years ago, when the northwest face of Mount Aksoual collapsed. The collapse was triggered by seismic activity, sitting as it does close to a major tectonic fault.
"The glacier would have melted before 11,700 years ago, the end of the last ice age," said geomorphologist Philip Hughes. "However, the cliff did not collapse until 4,500 years ago. The rock avalanche was therefore not triggered by glacier retreat." However, Hughes explained that glacial erosion probably did make the cliff-face prone to collapse, even if an earthquake was the final trigger.
Hughes described the village of Arroumd as “an amazing place” which was built using the rocks of the avalanche. However, he also joked about the ‘curse’ of the Arroumd landform. “Several incidents occurred at the site, including some accidents — minor, thankfully — and mystery ailments to those who went there." Hughes said. “This year we encountered severe whirlwinds when entering the valley, just days after the paper was published. We were unable to stand on our feet, which is rather unusual for this part of the world where climate is often hot and calm."
Featured image: The village of Arroumd. Photo credit: Phillip D. Hughes et al./GSA Bulletin