When was the first not-icy desert formed?

Unearthing Earth’s Oldest Dry Spots: When Did Deserts First Appear?

Deserts. Just the word conjures images of stark beauty, resilience, and maybe a bit of scorching heat. But have you ever wondered when these arid landscapes first popped up on our planet? It’s a question that takes us on a fascinating journey through Earth’s deep history, a time of shifting continents and dramatic climate changes. Figuring out the exact moment the first desert formed is tricky, like trying to find the first grain of sand on a beach, but scientists have pieced together some pretty compelling clues.

Way Back When: Deserts of the Permian Period

Believe it or not, deserts might have been around for a very long time – potentially as far back as the Permian period, roughly 299 to 251 million years ago. Picture this: all the continents squished together into one giant landmass called Pangaea. Because it was so huge, the areas in the middle were super dry, basically creating a massive desert smack-dab in the center of the world.

The Cenozoic Era: When Modern Deserts Took Shape

Atacama: Could This Be Earth’s Most Ancient Desert?

Now, let’s talk contenders for the “oldest desert” crown. The Atacama Desert in Chile is a strong candidate. It’s been at least somewhat dry for around 150 million years. And get this: the heart of the Atacama has been bone-dry for about 15 million years! How does a place stay that arid for so long? Well, it’s a perfect storm of geography and weather. It’s sandwiched between two mountain ranges (creating a “rain shadow”), plus it’s right next to the cold Humboldt Current. Talk about a recipe for aridity!

The Namib Desert: Another Old-Timer in the Running

Don’t count out the Namib Desert along the coast of Namibia, though. It’s another ancient contender, thought to have started forming around 55 million years ago. The story of the Namib is tied to the opening of the Atlantic Ocean and the arrival of the cold Benguela Current. This current basically put a lid on moisture, turning the inland area into the desert we see today.

The Sahara: A Relative Newcomer

You might be surprised to learn that the Sahara Desert, that vast expanse of sand in Northern Africa, is actually a relative youngster in desert terms. It’s only been around for about 7 million years. The drying up of the ancient Tethys Sea and changes in the Earth’s tilt had a big impact on monsoon patterns, leading to the Sahara’s desertification. That said, there’s evidence suggesting it was at least sometimes dry for much longer, going back perhaps 5.3 to 2.6 million years.

Taklamakan Desert: A Desert Born from Mountains

Let’s hop over to Asia and talk about the Taklamakan Desert, the second-largest shifting sand desert on the planet. This place, nestled in the Tarim Basin, started turning into a desert around 7 million years ago. What caused it? The uplift of the Tibetan Plateau, which blocked moisture and created a “rain shadow” effect. Some studies even suggest the Taklamakan could be as old as 25 million years!

Tectonics and Climate: The Dynamic Duo of Desert Formation

So, what’s the secret sauce behind desert formation? It’s a combination of tectonic activity and climate shifts. When tectonic plates collide and create mountains, they can block moisture and create those rain shadow deserts I mentioned earlier. Ocean currents play a huge role, too, by influencing rainfall patterns. And let’s not forget about those long-term changes in Earth’s orbit (called Milankovitch cycles), which can have a ripple effect on climate and the size of deserts.

What Makes a Desert a Desert?

What exactly is a desert, anyway? Well, the classic definition is an area that gets less than 10 inches (250 mm) of rain per year. But it’s more than just a lack of rain. Deserts can be hot or cold, sandy or rocky. The key is that there’s not enough water to go around, which shapes the landscape and how plants and animals have adapted to survive.

The Big Picture

Figuring out the exact age of the first desert is a bit of a puzzle that scientists are still working on. We know that dry conditions existed way back in the Permian period, but the Atacama and Namib deserts seem to be the frontrunners for the title of “oldest.” The story of how deserts form is a reminder that our planet is constantly changing, shaped by forces deep within the Earth and the ever-shifting climate. It’s a story written in sand, stone, and the relentless march of geological time.