Monday, February 3, 2014
This is Blood Falls in Antarctica.
Millions of years ago (no one is sure just how long), ice covered a lake in Antarctica. The water leached salt out of the ground below, and some evaporation also occurred. The lake became salty, three times saltier than seawater. With so much salt in it, the water could not freeze. More and more ice was deposited on top of the lake, until the lake was more than 1,200 feet below the ice.
The ice became part of the Taylor Glacier. As the glacier moves, it scrapes iron from the earth. This iron mixes with the water. In time, a crack formed in the glacier that allowed the lakewater to find a way to the surface. As the iron-rich water reaches the surface, it oxidizes -- and turns bright red with rust. This is what forms Blood Falls.
Blood Falls does not cascade into the ocean. About 3,000 miles due south of New Zealand is the Ross Sea, which bites deep into the interior of Antarctica. The western shore of the Ross Sea is bounded by the Beacon Supergroup, part of the Transantarctic Mountains. This geologic formation is so high that it prevents moisture from reaching the shorline. The valleys (each some 20 to 30 miles long) between the Beacon Supergroup and the shoreline are therefore incredibly dry -- some of the driest places on Earth! The air west of the supergroup is very, very cold. In fact, it is so cold, that it plunges at near-hypersonic speed (200 to 300 mph) toward the ground. It heats up with friction as it does so, and when it reaches the ground it causes moisture there to evaporate. These "katabatic" winds also help keep the Dry Valleys of the Ross Sea some of the most moisture-free spaces on Earth.
The Beacon Supergroup traps an enormous amount of ice behind it. This includes the Taylor Glacier, which is in the Taylor Valley. At the west end of the Taylor Valley is Lake Bonney, a salty lake with an ice cover. An unfrozen body of water lies beneath the ice cover. Blood Falls pouts into Lake Bonney from the western end of the Taylor Glacier.
What's even more fascinating???
Microbes were trapped in the water of the subglacial lake 1,200 feet below Taylor Glacier. At first, these microbes used oxygen to survive, but soon all the oxygen was used up. There were, however, sulfates in the exposed rock. These microbes adapted to break down the sulfates. This frees iron, oxygen, and some by-products, allowing the microbes to use the oxygen to survive. Amazingly, the iron then reacts with the by-products -- forming sulfates again. The recycled sulfates are then used by the microbes to form oxygen again!!! It's a complete self-enclosed ecosystem that doesn't rely at all on the Sun, and has astonished scientists.