AlUla's Evolving landscape

Those that make it to the top of Jabal Abyad say it’s well worth the climb. At 2,093 metres high, the views from ‘White Mountain’, Saudi Arabia’s highest volcano, are truly epic. The panorama of the wildly beautiful Harrat Khaybar unfolds endlessly beneath, with a chequerboard of black and white volcanoes stretching to the horizon, like islands in an ocean of ancient lava flows. It’s a scene that speaks to the Arabian Peninsula’s ‘recent’ geological past - an extraordinary landscape forged by the force of nature around 20 million years ago.

Jabal Abyad is located in Khaybar, an ancient oasis a three-hour drive away from its sister city of AlUla. It is a well-named mountain: its gentle alabaster slopes give it the appearance of a snow-capped mountain in the middle of the desert. The distinctive colour comes from an age-old covering of silica-rich volcanic ash called comendite. It’s a stark contrast to the steep black basalt slopes of its near neighbour, Jabal Qidr, a textbook stratovolcano built up from generations of dark, fluid lava flows. And beneath both lie the expansive lava fields with their ashen volcanic vents, domes, cinder cones, and tuff cones creating a hauntingly beautiful ‘otherworldly’ moonscape.

The presence of tuff cones gives an important clue to the ever-changing geological story of this desert land: it was once underwater. Volcanic tuff cones form when rising magma meets water, explosively turning it to steam and creating plumes of fine ash that fall to form a distinctive, steep-sided cone. In this dry and desolate landscape, they might seem out of place. But while today AlUla is famously arid, its origins were very, very different.

The beautiful light-red sandstone that forms such a spectacular backdrop to AlUla was created 500 million years ago, at a time when the land was still lifeless. And a time when AlUla was not where it is today. Plate tectonics, those ever-moving ginormous pieces of the Earth’s crust, have shifted the continents to their current positions. And they are still moving today, slowly, about the rate at which your fingernails grow. Half a billion years ago, our planet looked very different. AlUla lay thousands of kilometres to the West. There were no beautiful mountains, no valleys, no sandstone outcrops. These were all things to come. 

AlUla lay on the edge of a super-continent, called Gondwana. Without forests, grasses, and soils, the erosion on this vast land was rampant, resulting in unfathomable quantities of sediment washed to the seas by rains and rivers. The iconic sandstones show evidence of this time. Massive braided rivers, over 100 kilometres wide, tumbled and rolled sediment, breaking it down, as it settled and was buried. Seas moved in and out, leaving their signs in the rocks we see today. All this sediment, thousands of tonnes of sand, was buried, where it was crushed and heated squeezing out the water and baking it into sandstone. Here it lay hidden, slowly drifting as plate tectonics moved and the world above carried on. Dinosaurs came and went. Mammals spread across the world. And sometime around 40 million years ago, as the Red Sea started to open, this hidden landscape was thrust upwards creating an enormous sandstone plateau. Erosion from the wind and rain has slowly created the landscape we see today.

Buried within the sandstone we see signs of this distant past, signs of a distant world. And sometimes, we even see signs that life was here all that time ago. A meandering trail of fossilised chevron-shaped grooves hints at some of the earliest life on Earth. These are the tracks of trilobites, extinct sea creatures that were among the first ‘inhabitants’ of AlUla more than 485 million years ago. Similar in appearance to woodlice, though more closely related to spiders, their enigmatic tracks are all that remain of a long-vanished world - no fossils have yet been found, but geologists are still searching.

They are helped in their quest by the relentless action of the elements. For AlUla is a landscape that is constantly changing, the sun, wind, and water continually remodelling the sandstone to create some of the most striking rock formations in the world - an unlimited source of entertainment for imaginative hikers, families, and visitors of all ages. Fish Rock, Face Rock, Mushroom Rock, and more all live up to their epithets: there is even something intensely alive about the Dancing Rocks, two sandstone towers carved into a single sculpture that seem to sway in unison.

Perhaps the most famous of all is Jabal AlFil—Elephant Rock. Towering 50 metres into the sky, there is no question of what it represents. So clear is the image that you’d be forgiven for thinking that some ancient civilisation had consciously carved the rock into the likeness of an elephant: indeed, the peoples of AlUla have proved themselves more than capable of such impressive feats. But the only artist at work here is nature itself. And, as time and the elements continue to abrade the landscape, so AlUla continues to evolve. From the wild volcanic harrat to the spectacular sandstone cliffs, AlUla is a story still being written in its rocks.