GRANITE PEAK PUBLICATIONS: Accompanying travelers to the national park since 2002

Dynamic Earth: Yellowstone geology doesn’t stay the same

Yellowstone Treasures‘s geology writing strives to keep up—

If you were to contemplate nature’s many facets and how quickly things change over the seasons and the years, you might think that you can at least count on the rocks and the mountains to stay the same. Wrong! Geoscientists will tell you that even mountains have their own dynamics. But their rate of change is much slower than humans can easily grasp in their relatively short lifetimes. Nature shapes the land we live on over centuries and millennia, but the rate at which geoscientists learn about it using new methods, ideas, and equipment is constantly accelerating.

Wanting to keep track of all this activity as it pertains to Yellowstone Park for the updated fourth edition of my guidebook, I was delighted when my old friend Dr. Jo-Ann Sherwin offered to bring us up to date about Yellowstone’s geology. I’ve known Jo-Ann ever since she was an outstanding student, whose advisor during her Brown University PhD research was my first husband Bill Chapple. She was the first woman to earn a PhD in their geology department and has gone on to a long career in research and teaching. She also lives in Idaho Falls, convenient to the west side of Yellowstone.

Jo-Ann reviewed the entire book and made numerous suggestions. She also rewrote large portions of our geological history essay, “The Stories in Yellowstone’s Rocks.” Our goal is to make our explanations accurate but concise and as clear as possible without any technical writing. Here’s a short sample from our essay that draws upon recent research into the source and age of the water for the park’s thousands of geysers and hot springs (hydrothermal features):

What makes the different hydrothermal features do what they do? Basically, the great volume of groundwater is heated by very hot rocks quite near the surface at Yellowstone.
There is a very large amount of old groundwater, at least 60 but perhaps greater than 10,000 years old, just above the magma below Yellowstone. The source of this water may have been the glaciers that covered the area or rain and snow in the surrounding mountains, 12 to 45 miles (20 to 70 km) distant. Present-day rain and snowmelt seep down and mix with this old water, become warmed to the boiling point, boil into steam, expand greatly, and find a way to escape upward. Most of the features occur where faults are common, making it easy for the heated groundwater and steam to return to the surface.

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