USA - Yellowstone-11.jpg
Yellowstone National Park. WOW! This is an area known as "Sulpher Caldron". It is a pond of bubbling mud. Sulpher gases mix with water and create sulphuric acid (about as strong as battey acid!). This dissolves the soil/rocks into mud. It is quite thick and the bubbles become very large before breaking. Despite the high acidity, it is safely viewed from an area above the caldron.
Makeup DayRoad TripYellowstonewallpaper