I was surprised to find that the road north was paved, surrounded as it was by a barren, gently undulating landscape of scrub and sand. A railway line ran parallel but was a poor travel option. Infrequent trains moved only slowly, on tracks rumoured to be laid without proper foundations. I was travelling with a local driver and a Turkmen guide towards the ancient city of Konye Urgench in search of inland saline soil deposits.
The bleak and unforgiving landscape was a stark contrast to the gleaming white metropolis of Ashgabat, the capital city of Turkmenistan, from which I had set out from earlier in the day. Ashgabat is a relatively young modern city with many public buildings and mosques clad in imported Italian marble but intertwined with relics of its former history under the Soviet Union. The streets are laid out as tree-lined boulevards with air-conditioned bus stops, chrome-plated traffic lights and small wooded parks containing statues of Lenin and Pushkin, a far cry from the emptiness of the Kara Kum or ‘Black Sands’ desert through which we now drove.
I was in Turkmenistan on a reconnaissance mission to locate sampling sites for inland saline deposits known as playa, or locally as tugai. The Kara Kum desert, which dominates most of the country, has average annual temperatures between-10°C and 40°C and little (if any) rainfall. Its arid conditions influence the evaporation of groundwater, a process that deposits distinctive layers of natural minerals within its soils. The mechanical properties of saline soils are not well known, but it’s clear that their physical effects can be disastrous for infrastructure placed on and within such soils – occasionally leading to the destabilisation of buildings. Moreover, the stability of these soils is highly sensitive to environmental change. My work, which aims to understand the link between saline soil structure and destabilisation, depends heavily on characterising extremely mineral-rich soil environments such as those found in the Kara Kum desert.
I spent most of the time at the crater’s edge, mesmerised by the hissing flames emitted from tiny fissures scattered around the crater’s base and occasional blasts of hot air as the wind changed direction
After a few hours we reached a settlement known as Erbent, an oasis first settled by nomadic Turkmen. Here, single-storey corrugated iron roofed houses sprout from the sand, most with a pile of gnarled wood for fuel, Russian motorbikes, fuel tanks, satellite dishes and power cables. The driver stopped to take on fuel before travelling off-road to Darvaza, sometimes dubbed ‘Hell’s Gates’.
In the strong afternoon sun, the Darvaza gas crater doesn’t look like much, just a blackened hole with yellow flames flickering around the base. But in the fading light, the crater begins to glow and a crimson aurora rises under the night sky. It’s thought that the crater was formed by a soviet gas exploration crew three decades ago when prospectors encountered a gas-filled cavern below the surface, which caused the surface to collapse. Locals set fire to the gas as a precaution and it has been burning continuously ever since. The remains of what looks like parts of the drilling operation are partly buried at the base of the crater.
We set up tents a distance from the crater to avoid any toxic gas vapour. The driver lit a fire and set up a barbecue of shashlik kebabs, which we ate with hard round bread made with cotton seed oil, washed down with the local vodka the driver had bought. But the night was cold (-5°C) in the thin tent and I spent most of the time at the crater’s edge, mesmerised by the hissing flames emitted from tiny fissures scattered around the crater’s base and occasional blasts of hot air as the wind changed direction. The next day I would leave this amazing sight behind and I wondered whether it would soon be extinguished. Turkmenistan, which has been declared to have the world’s second largest gas reserves, now has a growing group of international customers knocking on its door.
Robert, an engineering geologist in the University of Cambridge Department of Engineering and a member of Clare Hall, is a UK chartered geologist and chartered marine engineer, and has more than 10 years of international experience in marine and coastal geotechnics. He is studying for a PhD on the engineering properties of natural saline soils.