Dune June

Discover what sand dunes are, the diverse dune ecosystem, how they shape shift with the wind and dive deeper into the mysterious subaqueous underwater dunes.

Deserts are known across the world as hot, arid and sandy climates and a bunch of thorny green cacti. Did you know, though that perhaps the most marvellous and extraordinary parts of the desert are what at first glance looks like heaps of sand? No, they are not, in fact heaps of sand, they are sand dunes. You must be wondering what sand dunes are and how they form, right? Well, sand dunes are hills that are formed when the wind blows sand behind an obstacle. Over time, as more particles collect, the dunes grow taller and larger. A sand dune can also be formed underwater due to the currents, called subaqueous dunes. A sand dune has two sides, the windward side and the slip face. The windward side is the direction in which the wind is blowing, causing sand and sediment to be pushed upwards. This side is usually rougher and you might see ridges on the windward side as well. The slip face is the smoother side, opposite to the direction of the wind. Now, I think I might be getting a bit too scientific, but I have a bit more nerdy stuff for you. The types of dunes. There are 4 major types of dunes- Linear, Crescentic, Star, Dome and Parabolic. Linear dunes are very conventional, most of them are like absolutely straight, two-faced mountains. Crescentic dunes, well their name is self explanatory! They are crescent shaped dunes, where the wide side is the windward side, and the slip face is a small semicircle. Star shaped dunes form when the wind is coming from many different directions, resulting in at least 3 slip faces. Dome dunes are the rarest. They are circular and do not have a slip face.

Me along with sand dunes in Oman.

Sand dunes are not just heaps of worthless sand. Not only do they act as natural barriers against coastal erosion and flooding and protect inland areas from storm surges, but also provide unique habitats for diverse plant and animal species. Let’s talk more about the ecosystem of a sand dune. Although sand dunes are not the most fertile, some plants with shallow root systems still manage to survive. Many animals call sand dunes their homes too. Snakes, scorpions, sand fish etc. make dunes a surprisingly diverse ecosystem. You must be wondering how sand fish can live in deserts. Turns out, they are not actually fish, but lizards! When I went for a desert hike in Oman at around the age of 8, I was so fascinated by how so many species managed to thrive in such extreme conditions, something which I will talk more about later. In some deserts in Arizona, U.S.A., you may find many succulents and cacti. This is because they can survive for months without water! Such species have learnt how to adapt to the arid climate of sand dunes. When I went to Jaisalmer in India, I also saw Great Indian Bustards, a critically endangered species endemic to only that area. The vegetation was not very rich, just a few little shrubs and snaking trees which had managed to survive. Yet the bustard seemed to thrive! In Oman, our guide sorrowfully explained to us that people engage in leisure activities such as dune bashing, which completely destroys the ecosystem.

A snake that I saw while desert hiking in Oman.

One of the coolest things about sand dunes is that they are not stationary, they shape shift with the wind! Whichever direction the wind blows, the sand particles blow along with it, eventually setttling and creating new dunes. Sometimes, after many, many centuries, the dunes turn into hard rock cliffs. It’s almost like sand fossils! Lençóis Maranhenses national park in Brazil has a stunning series of constantly shapeshifting dunes with water in between them. Around the world, deserts and sandy beaches are covered with sand dunes, but did you know that sand dunes can form underwater too? As I mentioned earlier, underwater dunes or subaqueous dunes are dunes which form completely submerged underwater. You must be wondering how they shape shift with no gusts of wind to blow them. You might remember from one of the previous paragraphs that strong underwater currents, often caused by lunar pulls are the reason behind this phenomena. Subaqueous dunes also have a windward side and a slip face. Although subaqueous dunes may not be part of the stereotypical arid dune ecosystem, they are very much ‘real’ sand dunes. Although not as ecologically diverse, the are sometimes home to kelp or seagrass forests. Sometimes, they also harden over time to create solid shale or rock. An example of subaqueous dunes are found off the coast of the Bahamas Islands.

At first, I also thought that sand dunes were worthless heaps of sand, until I went to a secluded desert in Jaisalmer when I realised that they aren’t. Hopefully, through this post you learnt the same thing as I did, without having to travel miles and miles to a desert.