a Convergence of Wonders (the name derived from the influence of the Cascadia Subduction Zone, a convergent boundary). I had reached day 10 when we arrived and started exploring Yellowstone National Park, but was, uh, slightly distracted by another two week trip, a more personal trip. I'm home now, and I expect to wrap up this series now.
Fumaroles are steam vents. Sometimes fumaroles are short-lived features in the immediate aftermath of violent volcanic eruptions, but in places like Yellowstone (and Lassen Volcanic National Park in California) they are more permanent in nature. Sometimes they are transitional in nature, depending on the time of year and availability of groundwater. Some geysers erupt so rarely that they might as well be considered fumaroles that occasionally explode.
in the last post, Mammoth Hot Spring, was a mountain of calcium carbonate derived from the solution of limestone layers along the pathway of groundwater movement. Most of the hot springs in the park are within a rhyolite caldera, and most of the springs have much less voluminous deposits made mostly of silica. White Dome Geyser, below, is the highest silica dome in the park at twelve feet.
As we started south to leave the park, we made a short stop at Grant Village to have a look at Yellowstone Lake, a huge body of water (132 square miles) that is the largest freshwater lake above 7,000 feet in the country, and possibly the world. The lake lies within the Yellowstone Caldera, and recent activity has caused parts of the lake bottom to tilt. Some shorelines are rising and others are falling.
I also took a moment to say hi to Nina Fitzgerald, a ranger at Yellowstone. She is a fellow geoblogger, and has been writing a great series of posts about her experiences in the park system. You can catch her work at Watch For Rocks.