Great Mountain' Geyser, throwing up clouds of steam and boiling water, Yellowstone Park, U.S.A.

Great Mountain' Geyser, throwing up clouds of steam and boiling water, Yellowstone Park, U.S.A.

The 'Devil's Inkwell' bubbling and boiling over hidden fires, in famous Yellowstone Park, U.S.A.

The 'Devil's Inkwell' bubbling and boiling over hidden fires, in famous Yellowstone Park, U.S.A.

The 'Devil's Inkwell' bubbling and boiling over hidden fires, in famous Yellowstone Park, U.S.A.

Where the Earth’s great fires are still unquenched – Black Pearl Geyser, Yellowstone Park, U.S.A.

Glittering spray from "Constant" Geyser, and steam from "Black Growler," Yellowstone Park, U.S.A.

Glittering spray from 'Constant' Geyser, and steam from 'Black Growler,' Yellowstone Park, U.S.A.

Black Growler', whose steam kills trees, and whose roaring startles tourists, Yellowstone Park, U.S.A.

Black Growler', whose steam kills trees, and whose roaring startles tourists, Yellowstone Park, U.S.A.

Black Growler', whose steam kills trees, and whose roaring startles tourists, Yellowstone Park, U.S.A.

Wild Buffalo, One of America’s 'First Families,' at home on a sunny slope, Yellowstone Park, U.S.A.

Wild Buffalo, One of America’s 'First Families,' at home on a sunny slope, Yellowstone Park, U.S.A.

Wild Buffalo, One of America’s 'First Families,' at home on a sunny slope, Yellowstone Park, U.S.A.

Cleopatra Terrace and its mirror like pools - Mammoth Hot Springs, Yellowstone Park, U.S.A.

Cleopatra Terrace and its mirror like pools - Mammoth Hot Springs, Yellowstone Park, U.S.A.

Cleopatra Terrace and its mirror like pools - Mammoth Hot Springs, Yellowstone Park, U.S.A.

How an overflowing spring begins to build a terrace of 'geyserite' deposits, Yellowstone Park, U.S.A.

How an overflowing spring begins to build a terrace of 'geyserite' deposits, Yellowstone Park, U.S.A.

How an overflowing spring begins to build a terrace of 'geyserite' deposits, Yellowstone Park, U.S.A.

A Mountain of 'Petrified Water'- Pulpit Terrace and Mammoth Spring Hotel, Yellowstone Park, U.S.A.

A Mountain of 'Petrified Water'- Pulpit Terrace and Mammoth Spring Hotel, Yellowstone Park, U.S.A.