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Yellowstone
Welcome to the world’s first national park – Yellowstone! The golden rocks, effervescent waters, teeming forests, meadows and streams of Yellowstone have been dually christened by the United Nations as a World Biosphere Reserve and a World Heritage Site. This is North America’s Serengeti, where 1,700 kinds of plants sustain 60 mammal and 311 bird species. Here, 150 lakes and 500 streams give birth to mighty rivers and thrive with 24 species of fish. The generally placid flow of these watercourses is spectacularly interrupted by nearly 300 waterfalls.
Like inverted waterfalls, Yellowstone’s 300 geysers erupt skyward, flying in the face of the old adage, and arguing instead, that what goes down must also come up! Less flashy, but equally intriguing, are the geysers’ cousins: hot springs, fumaroles, mud pots and travertine terraces. These geothermal features are variations on the physics of boiling water, are ten thousand in number, comprise half of the planet’s total population of geothermal features, and yet are concentrated in the 2.2 million acre square in the upper left corner of Wyoming’s map simply labeled: Yellowstone.
Here, tourism became a science. Here, the U.S. Army defeated extinction by protecting the last of the American bison. Here, big government and big business united to preserve something greater than the revenue it generated. Here, preservation became an ethic.
Yellowstone is the example touted to help justify the establishment and protection of 3,600 other national parks in 143 different countries. It’s an adventurer’s dream, meticulously planned. It’s the first and last word of the favorite vacation story. It’s where many first fall in love: with the outdoors, with geology, with wildlife, with history, and with photography. It’s also where you can fall in love with all those same things, for all the same reasons, plus many more. It’s the “every-park” for everyone. Welcome to Yellowstone!
Old Faithful Geyser
Named by the Washburn Expedition for its predictability, Old Faithful’s eruptions range from 45 to 90 minutes apart. The time between Old Faithful’s eruptions are slightly longer than when it was discovered, but the park rangers can still predict them with surprising accuracy. The most powerful eruptions can reach 185 feet, last for five minutes, and discharge 8,000 gallons of water. Old Faithful, though not the tallest or the most powerful, is still the world’s most famous geyser. 25,000 people a day see Old Faithful go off, with as many as 5,000 people per eruption.
Geysers are rare; they occur where Earth’s molten mantle is near the surface. Usually 20 to 25 miles of crustal rock overlays the mantle. In Yellowstone, the crust might be only three miles thin. Thin crustal rock also has to be fractured deeply enough that ground water can drain down to where the mantle keeps bedrock searing hot. Finally, a fracture needs a constriction point near the surface.
The beginning of the geyser’s eruption process is the moment the previous eruption ends. After all the water in a fracture has been blasted out, groundwater surges back down. The first water to arrive at the bottom instantly boils, but before it can escape as steam, cooler water pours in on top. The phenomenal burden of the growing water column increases the pressure and raises the boiling point, keeping most of the water in its liquid state. Slowly, tiny steam bubbles fight their way upwards against the crushing weight of the water.
At a constriction point, the bubbles merge and grow until at last they have enough power to lift the upper portion of the water column up and out, overflowing the geyser’s pool or spout. This pressure release allows all the superheated water below to instantly vaporize and the geyser erupts, taking any additional groundwater upward in the blast. When all of the superheated steam is expelled, the process begins again.