Friday, January 16, 2015

The Magic of Yellowstone

Columns of steam rose from the valley behind a curtain of dark green trees as we pulled up to the trailhead. Five chatting friends tumbled out of the bright yellow Bombardier snowcoach into still morning air. With the satisfying “click” of boots locking into skis, and a few words about technique, we took off down the old road-turned-ski trail.

From the start I was distracted by tracks. The huge hind feet of snowshoe hares were like exclamation points dotted by their tiny front feet. “SNOW!!!” They seem to shout, and we joined in their enthusiasm. Pine martens had sewn dotted lines over the drifts in their typical stitch of paired tracks at an angle to their direction of travel. Red squirrel tracks visited each tree like a connect-the-dots coloring page. Across the sparkling Fire Hole River, an otter slide nicked the bank. All of these familiar friends made me feel at home.

Then, a large, messy trough of tracks entered from the woods, and started post-holing down the center of the groomed skate lane. Too round to be boots, too big to be deer, these tracks were from bison. I don’t see that back home! Here in Yellowstone National Park, though, bison are more common than deer in the winter, and the tracks of elk and wolves commonly pock the ski trails as well.

While the animal signs were fun to see, they weren’t our goal for the day. At the end of this trail sits the Lone Star Geyser. Named for its remote location – three miles from its nearest neighbor (Old Faithful itself) – this is one of the biggest geysers in the park. Its large cone, formed slowly by silica that precipitates out of the water, chronicles a very long life.

Since at least 1872, Lone Star Geyser has been erupting approximately every three hours. It begins with a heat source – shallow magma chambers left over from one of the largest volcanic eruptions known to have occurred in the world. Then water – rain and snow – seeps into cracks, fissures and cavities in the rock above the magma chamber. As the heated water begins to rise again, it may pool in an underground reservoir capped by a constriction. Minerals from the water precipitate onto the walls, making them pressure-tight. This narrow tube of resistant rock keeps the water from rising freely, as it does in the many hot springs in Yellowstone.

Water nearest the surface does cool down, but it can’t circulate in the tight quarters. Instead, it pressurizes the water below it like the lid on a pressure cooker. Higher pressure means that the water in the chamber can heat to above the normal boiling point. But it can’t heat indefinitely. The water nearest the magma eventually starts to steam, and the resulting bubbles burst through the geyser’s vent, carrying splashes of water with it. This reduces the pressure in the whole system. The superheated water flash boils into a column of steam, and erupts in a spectacular display of hydrogeology.
This is exactly what was happening as we skied the last of our 2.5-mile route up to the Lone Star Geyser. Steam billowed from the impressive cone, and water splashed onto the barren moonscape of bare mineral deposits and snow. A dull, frothy roar accompanied the spectacle. [View a video on the Cable Natural History Museum’s Facebook page!]

As we milled around the viewing area, taking photos, shooting video, and just being amazed, some tentative sunshine broke through the clouds. In the steam cloud, a rainbow appeared, and we couldn’t believe our luck. We skied back with soaring hearts and full memory cards.

The thick forests we skied through, with their plentiful wildlife and beauty, are all protected because of what we just witnessed. Yellowstone has the world’s largest and most diverse array of geysers, hot springs, mud pots and steam vents. It was these features that prompted the creation of the world’s first national park on March 1, 1872, and eventually led to the creation of the National Park Service in 1916. While the animals we saw on the trip weren’t the goal of the park, they have benefitted dramatically from its protection. Bison, wolves, cougars, and more would not be here in this healthy ecosystem if it weren’t for our fascination with the geysers.

In my mind, that makes the eerie views of steaming valleys even more magical. 

Great day to ski: The wide, flat road along the Fire Hole River makes a great place to ski and chat with friends! 
Photo by Emily Stone

The Lone Star Geyser only erupts every three hours, and the sun only came out one that day. We were very lucky to see a rainbow in the steam! Photo by Emily Stone. 
Snowshoe hares have increased in the park since the 1988 fires increased the regeneration of lodgepole pine. Photo by Emily Stone

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