Yellowstone, Montana, Wyoming ... places that for us, Globe Trotters, have made us dream for years. And here we are !!
In the middle of the many fumaroles and geysers of the Norris Geyser Basin i>, we savor. The show is magic, splendid b>! We feel the Living Earth bubbling under our feet b>. Normal you will say: we are pile hair over an enormous magmatic chamber (at only 3 400 m under us, ie "the thickness of a sheet of cigarette paper compared to the dimensions of the Planet"). The Yellowstone National Park is located in the giant caldera (70 km in diameter!) Of the Supervolcan, the Yellowstone Volcano. B>
The last eruption dates back 640,000 years (a little bit of time!); It was - according to experts - apocalyptic. More than 1,000 km3 of debris, ashes and stones were thrown in all directions and more than 50 km above sea level. Today, the Yellowstone volcano is "just" asleep b>. The kettle continues to boil and scold, as shown by the many annual earthquakes, the 10,000 geysers, the many pools i> (hot springs) Detour of a path, mud pots, fumaroles ...
In short, it lives! And it is quite impressive to say that we are "in the heart of the volcano" while around us, they are hills and forests. It is better understood then that it was not until the 60s to realize that this place was the caldera of a gigantic volcano, not just a valley.
- But where do these pretty colors come from, pretty magical ??
- Color blue / turquoise: very hot water (more than 90 ° C). Li>
- White: water at 73 ° C (cyanobacteria) li>
- Yellow: water between 60 ° C and 70 ° C (mushrooms - 62 ° C) li>
- Green: water between 56 ° C and 60 ° C (algae) li>
- Red: water <56 ° C (protozoa) li> ul>
Faced with this superb show of color b>, one could forget that this beauty is caused by microscopic organisms invisible and thermophilic b> (= who love the hot). At high temperatures, these are mainly bacteria; At lower temperatures we will find algae and protozoa. The first biologist to recognize the relationship between colors and microorganisms was W.H.Weed in 1889