Dimmuborgir, Dettifoss and Hverarönd

The next highlight of the Iceland trip was our entry into the surreal world of Dimmuborgir, known as the lava rock labyrinth.

We explored the impressive surroundings on a walk.

The bizarre columns and ridges at Dimmuborgir are the remains of steam vents that formed when lava pooled over marshland. As it flowed over the wet ground, the water within it began to boil, and steam rose to the surface through vents up to several meters in diameter. After the crust of the lava sheet solidified, molten lava continued to flow beneath. Eventually, the crust collapsed, but the vents and parts of the cooled-down lava sheet remained.

Watch out, but we already knew about the faults.

Then we stopped at Dettifoss (Icelandic detta "fall"; foss "waterfall"). The "double fall" underlines that it is the second most powerful waterfall in Europe after the Rhine Falls.

Here, the Jökulsá á Fjöllum River plunges into the Jökulsárgljúfur Gorge.

Spanning about 100 meters wide, the waters plunge 44 meters into the depths, generating about 85 megawatts of electrical power.

The gray-brown waters continue to flow about 30 kilometers into the Arctic Ocean.

 

Many bridges on Ring Road 1, Iceland's main highway, are single-lane. The old bridge is now used by pedestrians to cross the Jökulsá á Fjöllum River, while downstream - in the background - a new two-lane bridge carries vehicular traffic. Note: Iceland has no railroads.

On our way to Hverarönd, a field of volcanic activity with hot springs, we had to cross the Námaskarð Pass (Icelandic náma, "mine"; skarð, "pass") and saw water vapor from a geothermal power plant in the distance.

Hverarönd is characterized by a variety of hot springs, boiling mud pools and mud pots, and solfataras. Sulfur used to be mined here ( náma),

Solfataras are fumaroles with temperatures ranging from 100 °C to 250 °C. These post-volcanic exhalations consist of hydrogen sulfide (H₂S), carbon dioxide (CO₂), and water vapor. The hydrogen sulfide produces the distinctive smell of rotten eggs. 

 
Upon contact with atmospheric oxygen, hydrogen sulfide oxidizes to form elemental sulfur and sulfur dioxide, which dissolves in water to form sulfurous acid (H₂SO₃). 

 
This acid corrodes the rock and soil and, together with the hot water vapor, causes the mineral components to decompose. This often results in the formation of mud pots, from which the gases escape with the formation of bubbles.

The sulfur-laden soil stifles all plant life.

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