Yellowstone National Park - paint pots

When hot water rises from within the earth and mingles with dissolved carbon dioxide, you get a weak solution of carbonic acid, and thus terraces. When hydrogen sulphide rises, it is used by some micro-organisms as an energy source. They help convert the smelly gas to sulphuric acid in a process that I like to think of as a reverse fart. The sulphuric acid breaks rock down into clay, forming mudpots, sometimes called paint pots when the slurry is particularly colourful. Gases escape through the wet clay and cause it to bubble and plop loudly, resuming its original fart-like nature.



These acidic hot springs have a limited supply of water. More water leads to less viscose “paint.”



In drier conditions the mudpots are thick and sluggish, bubbling slowly and belching clouds of gas - a bit like bucks night revellers after their 2am kebab.



The hottest surface vents are fumaroles. Their underground systems contain very little water, but reach far down into hot rock masses. When water does drain into the fumaroles’ plumbing, it converts instantly into steam and bursts out of the vent. The fumaroles above are actually shape shifters. When there's more water around, they're paint pots. When they dry out a bit, they turn into constant steam jets. I kept well clear of these vents. I’m still afraid of death by scalding.