Many people do not know what a sabkha is. Even fewer, if they saw one, would find it beautiful and worth protecting.
But sabkhas, as the low-lying coastal salt flats along Abu Dhabi's western shores are called, were making the emirate famous long before any of its man-made attractions. Ask a geologist anywhere about the UAE's capital and they will immediately recall Abu Dhabi's sabkhas - which are the largest in the world.
Among the sabkhas' most ardent supporters is Prof Graham Evans, a professor emeritus at Imperial College, London.
Prof Evans has been studying Abu Dhabi's sabkhas since the early 1960s and visited again this month. He was accompanied by his associate Dr Tony Kirkham, who has been campaigning on behalf of the sabkhas since the mid-1990s.
Their goal: to raise concern among anyone who will listen. A surge in development means the sabkhas are quickly disappearing and with them Abu Dhabi's ownership of a piece of nature that could help unlock mysteries about ancient sea levels.
"We have seen what has been going on and we feel horrified," said Prof Evans. "For the past 10 years, we have been trying to persuade the Government and various agencies that this [seemingly] rather uninteresting salty plain is unique in the world and they should preserve it."
The sabkhas lie along the coastline west of Abu Dhabi city, stretching all the way to its western-most parts. They extend up to 15 kilometres inland.
Their harsh beauty will evade those observing them from the comfort of a car. A closer look is required to appreciate the large expanses of salty crusts, forming various shapes. In winter, the surface is flooded with rainwater. In drier months, as the water evaporates, the crust cracks into almost symmetrical polygon forms. In other areas, there are whitish wrinkles, created by tiny organisms.
Because of the high salinity and the hard crust, plants do not grow on the sabkhas. The salinity makes them inhospitable for animals too. Cynobacteria, however, are able to thrive. They form large patches on the sabkha surface.
When Prof Evans arrived in Abu Dhabi in 1962, he found unspoiled stretches of sabkha that yielded discoveries with world-wide significance. By 1996, when Dr Kirkham was living in Abu Dhabi, the original sabkhas studied by his former tutor and his colleagues had been spoiled by human activity.
Dr Kirkham identified three areas of exceptional significance and lobbied for them to be protected. They are along a 30km stretch of coastline in Al Dabbiya, approximately an hour's drive from Abu Dhabi city. The scientists think it is not too late to protect them today.
"There are roads and pipelines, but it is still reasonably well-preserved," Dr Kirkham said.
Civil work and oil and gas infrastructure projects, dredging and infilling are the main threats. The industrial area of Musaffah is a typical example.
Dr Thabit Zahran al Abdessalaam, the director of the biodiversity sector at the Environment Agency - Abu Dhabi, agreed that saving at least some of the sabkhas should be a priority.
"It is something we need to look into seriously, and at the present moment we are not," he said.
"It is an issue of awareness and we scientists are to blame," he said, explaining that a parallel can be drawn with the ways mangroves were regarded here in the past.
Not so long ago, mangroves were considered useless swamps and were destroyed. Now, their conservation profile is a lot higher and there are many efforts to protect or replant them.
Sabkhas are part of a living system which includes some of Abu Dhabi's off-shore islands, its shallow sea lagoons and coral reefs. A vivid description of the dynamics that formed the sabkhas is presented in the book The Emirates - A Natural History.
Sabkhas form close to seas as the salts produced by coral reefs are deposited on land. In the summer months, water evaporates and a hard crust of calcium carbonate gypsum and other salts forms just below the surface. This crust prevents plants from settling on the sabkhas and it also ensures they are flooded by rains. As the rainwater cannot seep into the ground, it slowly evaporates, forming the sabkhas' unique crust.
Prof Evans believes that explaining the processes forming Abu Dhabi's sabkhas can be done by a museum, which could turn them into a natural history attraction.
And the sabkhas still have a role in science. This month, Prof Evans and Dr Kirkham collected 20 samples from hills of ancient origin, dotted around the sabkha surface.
They are looking for funding to enable them to date the newly collected samples. The information, they said, will yield important details about past periods of sea level rise - and could provide a yardstick for global warming.
The first adventure: his arrival
The story of how Graham Evans arrived in Abu Dhabi is like something from an adventure book.
He was brought in by the British Royal Navy, one of the few transport options in the autumn of 1962.
He camped on Saadiyat Island with two research students, plus an Omani guard, a camel and a cat which "appeared from nowhere".
His wife was also there, as the couple were supposed to be on their honeymoon.
"There was just dates, fish and tinned food," said Prof Evans, remembering how his young bride had tears in her eyes once, when after a visit to the market, he appeared with an onion and a head of lettuce.
"The fort," he added, "was the biggest building in town."
His research team also got unwanted attention after the research students were lost at sea and spent the night in a boat during a storm.
Yet, the expedition was to yield a discovery which "caused an enormous stir in the geological world".
Exploring sites on Saadiyat and Musaffah, Prof Evans discovered that the mineral anhydrite was forming just below the sabkha surface.
"This mineral is common on the geological column as a cap rock in oil fields, in successions of carbonate rocks all over the world," Prof Evans said.
"It was always assumed it was formed in deep water."
But in Abu Dhabi it was formed in coastal flats, which were flooded by some water, but only occasionally.
"This is now in geological textbooks all over the world," Prof Evans said.
