AlUla's surprising geodiversity

Iconic. Mesmerizing. Breathtaking. Just a few words to describe the incredible landscape of AlUla. And it truly is incredible. For over 40 million years, wind and rain have carved out beautiful natural formations. Formations that look like giant elephants, mushrooms, or even fish swimming through a sea of soft sand. You can stand beneath the towering, smooth, round sandstones, lost in their presence. Or you can stand high up, overlooking a landscape like nowhere else on Earth.

AlUla is well known, and celebrated for this spectacular landscape. Even now, driving through AlUla every day, I am still struck by the sheer beauty of the landscape around me.

What is more spectacular, and perhaps even more surprising, is that the landscape of AlUla is incredibly diverse. There are jagged mountains, large expanses of sandy plains, and even flat, dark plateaus raised high above us. This diversity is because of the rich geology. We call the different rock types in an area the geodiversity. 

The geodiversity of AlUla is something quite remarkable. Towards the south of AlUla, the rocks go back to almost a billion years ago: an astonishing age to conceive. Almost a billion years. This was a very long time ago when our beautiful planet was a very different place. The continents were very different, the oceans very different.

Those clues to the past can be found in the rocks.

In the south of AlUla are igneous and metamorphic rocks. These are hard, solid rocks, which crumble in blocks when they are broken down because of how they formed. Igneous rocks are literally born from fire: they form from the hot molten rock deep inside the Earth. As the magma cools, minerals begin to grow. Sometimes the magma can be exposed on the surface (like lava flows), and sometimes it cools under the surface. These rocks are rich in a variety of minerals, but they are very hard, so they take a long time to break down, especially in a dry, arid environment. Metamorphic rocks are rocks that were originally something else. They can be made from an igneous rock, a sedimentary rock, or even another metamorphic rock, which has been crushed and heated, causing the original crystals to re-melt.

As we move towards central and north AlUla, we see the more familiar sandstones. Dark red sandstones in central AlUla give beautiful hues to the landscape as the sun rises and sets. These are very solid rock, very tightly squeezed and compacted, and are evidence of enormous delta systems and rivers 540 million years ago. And to the north, the slightly softer, 500 million year old light-brown sandstone outcrops, rounded by thousands of years of gentle wind erosion.

High above AlUla, you will see a large, flat dark plateau. This has a very fiery past. Around 10 million years ago, a huge bubble of magma rose up from inside the Earth, and when it reached the surface, this super-hot liquid poured out from volcanoes. The remains of these volcanoes can still be seen on Harrat Uwayrid, the largest Nature Reserve in AlUla, surrounded by hundreds of kilometers of the dark basalt that seeped out from inside the Earth.

All of these different rock types in AlUla, this rich geodiversity, is more important than just getting geologists like me excited. Different rocks weather and break down differently, so they produce different landscapes. They also produce different soils because they have different minerals in them. These two things, landscapes and soils, are ecosystems for life. And this is one of the most remarkably beautiful things about the geodiversity in AlUla. Rather than a barren expanse of land, AlUla is rich and full of life. Plants, insects, reptiles, birds, and mammals (our planet’s biodiversity) are found all over this incredible area.

Here, we have five nature reserves. Five areas where plants and animals are protected. And each nature reserve is a very different environment because of the geology. Wadi Nakalah in the South is a mixture of sharp igneous and metamorphic mountains, and gravelly plains that is home to a range of species, all adapted to this type of landscape. Dozens of species of reptiles can be found, including the saw-scaled viper and Clifford’s Diadem snake. Arabian Gazelle and Nubian Ibex may be seen moving in the distance, elegantly, effortlessly, scaling the steepest of slopes. A huge number of birds can be see, including the enormous Steppe Eagle and the Imperial Eagle. All these species, and more, at home in a landscape that began almost a billion years ago.

Our largest Nature Reserve, and a UNESCO Man and Biosphere Reserve, Harrat Uwayrid is a completely different environment to the mountainous looking lands of Wadi Nakalah. Here basalt plateaus spread for hundreds of kilometers. It looks like nothing should be living here. But it is incredibly rich in life. Plants grow where you wouldn’t imagine they could. Insects flutter. Birds tweet. And foxes bark. This huge expanse of land, is home to a myriad of different species. It is another different environment, shaped by the geology, and where hundreds of different species have adapted to thrive.

My colleagues at The Royal Commission for AlUla are working to protect an restore these unique ecosystems, to ensure that the wildlife is thriving in not just protected areas, but across the whole AlUla region. From the smallest of insect, to the largest of birds, from the most beautiful flower to the most unassuming bush, all life plays an important role in the ecosystem. And a rich ecosystem not only provides boundless wellbeing for all, but a thriving, sustainable ecotourism sector enriching the lives of local communities.

And this beautiful geodiversity is not only important to animals and plants. It the reason that civilizations have settled here for thousands of years. People have used the landscape to build their cities. They have used the rocks as great fortresses, protecting their cities on one side, like we see at Dadan. Or used the softer, younger sandstones to carve the most beautiful structures into the rocks, such as those at Hegra. The geology has played a large part in the lives of our ancestors.

The landscape we see today was not always like this. The rocks, those sharp, unsurmountable igneous and metamorphic rocks, the beautiful natural formations, were buried below the ground for over hundreds of million years. Heat and pressure from the immense tectonic forces created massive cracks in the rocks. When these rocks were thrust up high above ground around 40 million years ago, these hairline cracks were finally exposed. Gentle the wind began to work. Grain by grain, these hairline cracks grew, destroying the rock that once was. Those hairline cracks got wider. Some became so wide you could stand between them. Others became so wide a whole city could be built between them.

Rocks. Dark rocks. Sharp rocks. Red rocks. Round rocks. They are so much more than just rocks. More than a silhouette on a landscape. They hold the secrets to the history of our beautiful planet. And these different rocks all around us, have created beautiful, rich, fragile environments that are different from one another, and are the only home for so many unique species in AlUla.

This incredibly rich geodiversity here in AlUla has led to a unique and rich biodiversity.