Gallatin County

Grand Prismatic Spring

It's the largest of Yellowstone's many colourful hot springs. It's massive and stretches approximately 200 feet (61m) across. The high temperature of its water 160F (70C°) ensures that the spring is often cloaked in steam.

Deep beneath, the magma from the active volcano heats water that rises to the surface through fissures in the rocks. The hot spring pours almost 1900 litres of hot water each minute into the Firehole River.

The intense blue colour is due to sunlight being scattered by fine particles in the water. The spring often appears to have a blue haze hovering over it. This is caused by the steam reflecting the blue from the water.

And indeed, if the sun isn't shining, the blue is less intense.

The yellow, orange, and brown colours are caused by microorganisms.

Excelsior Geyser

In the 1880s Excelsior Geyser erupted in bursts 50 to 300 feet high. The thermal violence formed the jagged crater and apparently ruptured the geyser's underground system, causing eruptions to cease after 1890.

On September 14, 1985, Excelsior roared back to life with forty-seven hours of major eruptions. It is impossible to predict when this dormant but powerful geyser's next eruption will occur.

But best not standing too close when is happens 😬Les mer