Deserts ‒ hot, dry and arid areas of land that cover more than one-fifth of Earth’s surface and can be found on every continent. One might think that this land can only provide the setting for fairy tales of genies and lamps, and does not provide much to the Earth’s ecosystem. While these dry lands have a moisture deficit, in that they lose more moisture through evaporation than they receive from annual precipitation, they offer much more than fantasy stories.
Though deserts seem to be barren and lifeless, they truly have a diverse and unique eco-system. The driest desert on Earth, the Atacama Desert in Chile, is home to a number of unique geological and geochemical features that separate it from the rest. This desert lies on the western border of South America and stretches across 1,000 kilometres of land, wedged between the coastal Cordillera de la Costa mountain range and the popular Andes Mountains, which separate Chile and Argentina.
While the outskirts of the Atacama is able to support communities of organisms that have also adapted to survive in harsh conditions, the desert’s hyperarid core is not able to support any form of plant and animal life. The desert’s inner core has been lacking moisture for roughly 15 million years due to the conditions that surround it. Many microbes have adapted to the extremely dry climate; in fact, these microbes found in the desert’s hyperarid core burst after absorbing too much rainwater.
The Atacama is home to some interesting geological features such as thick salt deposits called playas. Fan-shaped sediment deposits connect the desert plateau with the mountains that surround it, indicating that water once flowed from the Andes mountain range into the desert. Before the 1930s, the Atacama was also used to mine nitrate minerals that have a wide range of uses, from fertilisers to explosives.
The desert is also a delight to amateur astronomers who can experience 330 cloud-free nights each year.
An array of observatories, found along the Atacama Desert plateau track celestial bodies in our solar system and beyond.
A network of 66 telescopes, the Atacama Large Millimeter Array (ALMA), run by an international collaboration of scientific organisations from North America, Europe, Chile and East Asia, peers at faraway stars and their planets.
Though it may seem that dry lands such as the Atacama Desert have nothing to offer, this large area of land entices scientists’ curiosity and wets their appetite to learn more about the wonders of their geological, astronomical and ecological systems.
Danielle Martine Farrugia is a PhD student and science communicator at the Department of Physics, Faculty of Science, University of Malta. She is a Science Communication lecturer, hosts Radio Mocha Malta and runs Malta Café Scientifique.
Did you know?
• The driest part of the Atacama Desert on average receives less than a millimetre of rain each year.
• Date palm leaves are able to survive in the desert due to a unique wax mixture.
• Desert ants are able to learn many food odours and remember them for all their lives.
• Camels are able to go for weeks without water and can protect themselves from sand due to their nostrils and eyelashes.
• The desert tortoise is able to withstand temperatures in excess of 50°C and is able to survive without water for a year.
For more trivia, see: www.um.edu.mt/think
• A field trip to Namibia to study volcanic rocks led to an unexpected discovery. West Virginia University geologists Graham Andrews and Sarah Brown were exploring the desert country in southern Africa when they observed an unusual land formation. This was a flat desert that included hundreds of long, steep hills. This bumpy landscape was covered by a type of hill that is usually found in places that was once covered by glaciers, called drumlins. Indeed, drumlins are not a usual sight for desert landscapes. These drumlins featured large grooves indicating that the ice must have been moving at fast speeds to carve the grooves, showing that there wasn’t just ice, but an ice stream in the late Palaeozoic Age that occurred about 300 million years ago.
• Rain usually means that flora blooms; however this is not the case in the Atacama Desert. The hyper-arid core cannot tolerate water, and rain caused a massive extinction of most of the indigenous microbial species there. The soils were home to up to 16 different ancient microbe species. Unfortunately, after it rained the number of species went from 16 to two to four microbe species in the lagoons. This sudden change in precipitation can inform us about the biology of another planet ‒ Mars. One of the implications is about evidence of nitrate deposits. Large deposits of nitrates were found in the Atacama Desert that indicate long periods of extreme dryness. Nitrate deposits were also recently discovered by the rover Curiosity that roamed on Mars. Another implication goes back to the Viking spacecraft experiments conducted in the 1970s incubating Martian soil samples in aqueous solutions that need to be revisited based on this discovery.
For more soundbites listen to Radio Mocha on Radju Malta every Monday at 7pm on Radju Malta and Thursday at 4pm on Radju Malta 2 https://www.fb.com/RadioMochaMalta/