The American bison is Yellowstone's version of a Mack Truck. When push comes to shove, there is no contest: A 900-kilo bison wins.
Mist hangs in the air and early morning travel along the loop road through Yellowstone National Park grinds to a standstill. A hundred or so photogenic members of the park's Hayden Valley Herd have snarled traffic by languidly crossing the roadway, galloping across the dewy fields and plunging into the Yellowstone River.
This "bison jam" is a photographer's dream. But thoughts of getting anywhere quickly? Forget it.
"I love the grunting and roaring sounds they make," says Lisa Whitwell, an instructor with the Yellowstone Association Institute (the park's non-profit education partner that teaches visitors about wildlife, geology and conservation). "They're called 'the lions of Yellowstone' because of the noises."
Most visitors head for Yellowstone in the summer months, clogging roads with traffic jams of the human kind. But autumn is the ideal time to visit America's first national park -- the crowds have dissipated and the weather is still cooperating.
Rather a lot is made of Yellowstone's prolific wildlife -- bison, grizzly and black bears, elk, moose and wolves -- but it's humdrum H2O that has defined this landscape. Everyone who visits shoehorns in a stop at Old Faithful, the world's best-known geyser, guaranteeing a lineup of gawkers, cameras poised at the ready. It's as though this part of the planet invented geysers -- there are more than 300 in the park, a greater concentration than anywhere else in the world.
The kind of energy that powers Old Faithful bubbles deep below the Earth's surface, from magmatic heat that has propelled two million years of volcanic eruptions. Rainfall seeps deep underground, coming in contact with the scorching liquid magma, then rises to the surface as super-heated water. Along the way, the fiery water may run into roadblocks, increasing pressure until it finally breaks the surface, shooting skyward in a rip-roaring display of water and steam.
In contrast, water at the park's hot springs flows free and easy, slowly bubbling up to the surface, cooling and sinking back underground in a continuous cycle. When calcium carbonate is part of the chemistry, the water creates the unworldly colours and formations found at spots in the park like Mammoth Hot Springs. Mudpots are another park feature -- hot springs of acidic water that are essentially bubbling mud.
Yellowstone has all of these water formations -- more than 10,000 in total Half of the world's hydrothermal features including a still-active volcano are concentrated in a relatively small area.
Yet, none of this supercharged geothermal busy-ness seems to faze the herd of bison that have commandeered the roadway. I decide the best play is to tag along on their que sera, sera philosophy, set the parking brake, listen to the parade of grunts and roars, and just enjoy the ride.
NEED TO KNOW
-- In 1872, Yellowstone was established as the world's first national park. Today, it is also a Biosphere Reserve and World Heritage Site. See nps.gov/yell.
-- Near the park's north entrance, the 320 Guest Ranch has log cabins. See 320ranch.com.