Vandals have defaced an ancient rock formation in the Abu Dhabi desert in a “sad and shocking act of disrespect”. Volunteers attending a clean-up event at the Fossil Dunes site in Al Wathba discovered a carving and graffiti scrawled in spray paint on one of the stones. The site was created over a period of thousands of years, when sand swept by the wind mixed with calcium carbonate, causing it to harden and form natural sculptures that rise up from the sand. Its petrified fossil dunes, which look like works of art, are a popular visitor attraction on the outskirts of the city and can be reached by road. "I thought I was seeing things when I first saw it [the graffiti]," Abu Dhabi resident Hannah Androulaki-Khan, 24, from the UK, told <em>The National</em>. She was attending the clean-up, which was organised by Environment Agency Abu Dhabi . "It's not the big dune itself. It's one of the smaller ones next to it. My friend just went: 'Hannah, what on earth is that?' “There was graffiti on one of the dunes. It looked a bit faded as if someone had tried to rub it off. Then we walked round to the other side of the dune and there was much more graffiti but also a carving as well. They had actually carved their initials, saying 'D heart A' or something. “I couldn’t believe was I was seeing. It’s so incredibly disrespectful.” There was also rubbish littered around it, including rope, plastic zip ties, a broken lightbulb and bottles, she said. Ms Androulaki-Khan was so disgusted by what she saw she shared pictures on the Abu Dhabi Q&A Facebook page. The post attracted dozens of comments from people who were equally angry. Some said visitors often treat the site like a "playground", despite signs from the authorities warning people not to climb on the dunes. “It’s a shame that people can’t respect the different heritage sites available to the public. People crawl around on the fossil dunes all the time, adults as well as children,” wrote one member. “You can look at them, walk amongst them but don’t treat it like a playground. They have deteriorated a lot in the last few years. “Such a shame. The government is going to end up closing the site off because of behaviour like this,” she added. <em>Atlas Obscura</em>, which describes itself as the "definitive guidebook and friendly tour guide to the world's most wondrous places", compares Al Wathba to a setting out of a <em>Star Wars</em> film. “A few million years ago, when the area was covered by water, eroded sediments settled at the bottom of these bodies of water,” added the entry. “Over time, the fine-grained sand was covered by other layers of sediment. The layers became compacted and cemented together by different minerals, mostly salt crystals, into stable structures." “The formations got their shape from the interplay of wind strength and sediment supply.”