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Mike Horn

YEP 6 Exp Mongolia Day 13

Day 13 – Tirza, Nicolette, Leni

„Time to wake up! It’s 4am and we are going to climb some sand dunes today!” These were the dreaded words spoken to tempt us out of our warm sleeping bags and do one of the most physical challenges of this expedition to date.

Half an hour later all of us set off South towards the Hongoryl Els, which are the sand dunes of the Gobi. In our Scarpa hiking shoes, we quickly walked across the sand towards the dunes in darkness with only our Petzl headlamps and the moon to guide our way. When we finally reached the first sand dune, we took a moment to take in the great height and steep slopes of sand: “What? We’ll have to climb countless of these till we reach the highest sand dune?!”

So we started our climb up and up and up. When a dune has ripples due to the wind, it is more compacted and we slid less down. We also tried to walk on the ridges whenever possible, as the sand is more stable. Furthermore, on slopes with especially loose soil, it is easier to follow the tracks the people made in front of you. Mike also gave us the perfect suggestion to remove our shoes and walk in our socks. At the start it was strange to walk without shoes, but soon we got used to the feeling of soft sand between our toes. The advantage of walking in socks or barefoot is that you don’t get the uncomfortable feeling of having sand in one’s shoes.

While we were climbing up the many sand dunes, it was quite cool due to the constant wind blowing on our faces. So when we saw the sun rise, we were glad to see the light and feel the warmth of our beautiful sun’s rays on our skin. The sunrise was just magnificent. All of us took a seat on the sand dune and just marveled at the colours in the sky and the lighting up of the sand dunes.

When we finally arrived at the highest sand dune, we could see over the whole Hongoryl Els as well as the mountain ranges. A great feeling of insignificance but also majesty befell all of us. We realized that we were probably the first people to ever climb this sand dune. After sitting over an hour on the dune’s summit, listening to Mike’s stories of the Namib desert, the Amazonas and Antarctica, we ran slid down the dune. It was really fun to jump, slide and of course fall down the dunes… This was an experience and moment we will talk about for the rest of our lives: to see one of the most beautiful places on earth with the friends for life we made here over these last two weeks.

FACTS

The Khongoryn Els dunes lie north of the Baruunsaikhan Mountains 200 kilometres west of Dalanzadgad. Extending for roughly 185 kilometres they reach heights of 200 meters. The sound produced by the dunes rises to the name "singing sands".

Certain conditions have to come together to create singing sand: The sand grains have to be round between 0.1 and 0.5 mm in diameter, need to condain silica and have a certain humidity. The most common frequency emitted seems to be close to 450 Hz.There are various theories about the singing sand mechanism. It has been proposed that the sound frequency is controlled by the shear rate. Others have suggested that the frequency of vibration is related to the thickness of the dry surface layer of sand. The noise may be generated by friction between the grains or by the compression of air between them. Other sounds that can be emitted by sand have been described as "roaring" or "booming".

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