Admire the unique cluster of salt domes in the world

The salt dome cluster in the Zagros range was formed millions of years ago and is unique in terms of diversity, shape, formation and development process.

Impressive salt structure in Iran. (Photo: Amusing Planet).

Millions of years ago, the Persian Gulf was a much larger body of water than it is today, with many areas of the Arabian Peninsula to the south and Iran to the west submerged. Then the water evaporated and the sea receded, leaving behind a huge amount of salt. The salt layer is covered by sediments washed down from the mountains by rainwater. Over time, the sediment layer thickens, becomes dense, and weighs down the salt layer below.

Under such a situation, salt begins to behave like a fluid (a moving substance, without a fixed shape) leading to an interesting phenomenon called salt tectonics . The weight of thousands of feet (1 foot is about 0.3 meter) of sediment and rock presses down on the salt layer, causing the salt to rise up through the rocks. When a weak spot is found in the overlying sediment, the salt will rise through it and form salt domes . Occasionally, a salt dome will rise to the surface and spread horizontally, becoming a salt glacier.

All these impressive salt structures can be seen in the southern, southwestern and central regions of Iran. But the most notable example lies in the Zagros Mountains that run parallel to the Iranian coast in the Persian Gulf. The Zagros Range formed when the Arabian Plate collided with the Eurasian Plate, creating many mountain ranges and faults, allowing salt domes to appear.

Salt domes (hilly areas) and salt glaciers (dark areas) in the Zagros Mountains, southern Iran. (Photo: Amusing Planet).

According to UNESCO, nowhere else in the world are there such accumulated salt domes. This site is being considered for World Heritage status. The Iranian salt dome cluster is unique in terms of diversity, shape, formation and development process.

In the southern part of the Zagros range alone there are more than 130 salt domes. In addition to salt domes, this place also has many salt caves, including the longest salt cave in the world with a length of more than 6.4km in Namakdan mountain, salt glaciers, salt valleys, karst sinkholes and salt springs.

The salt dome cluster in Iran may be at risk of being damaged by future oil exploration activities. The reason is that impermeable rocks in salt domes often trap petroleum beneath other layers of rock. Salt domes elsewhere, such as the US, Mexico, the North Sea, Germany and Romania, are a major source of oil and have been exploited for many years.