If there’s one thing you should know about Yellowstone National Park, it’s that it’s always changing – and that can mean the appearance of a brand-new hydrothermal feature, which is exactly what happened last summer.
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The feature in question was discovered on August 5, 2024, when a park scientist driving through the Roadside Springs thermal area noticed a plume of steam rising through the trees surrounding a nearby marsh.
When geologists were sent to investigate, they confirmed that this wasn’t old news – they had stumbled upon fresh activity. “[A] new hydrothermal feature popped up right in front of our eyes—literally!” wrote geologists Jefferson Hungerford and Kiernan Folz-Donahue in the Yellowstone Caldera Chronicles.
If it weren’t for the steam, this new feature might look rather unsuspecting. Sitting at the foot of what was once a lava flow, the vent looks a bit like someone just took a spade to the ground, save for a thin layer of grey, silicious clay covering it. This barely-there covering indicates the presence of a hydrothermal vent, but one that is very young.

A close-up of the newly formed vent, taken in August 2024.
Image credit: Jefferson Hungerford, Yellowstone National Park (Public Domain)
Of course, the pretty unmissable plume of steam that appeared made it clear that there was a new feature there. According to Hungerford and Folz-Donahue, this plume continued to be strong through the summer and into the fall, before gradually disappearing come the winter.
“The feature remains active, but there is some water in the vent, decreasing the amount of steam that is released,” the two geologists explained. “Whether or not the strong plume returns in the summer of 2025 remains to be seen.”
The new vent sits in an area known for being hydrothermally altered, and it’s thought that this latest activity could be connected to similar activity that was first observed nearby back in 2003.

This aerial view shows the location of the new hydrothermal feature, as well as those that became active in 2003.
Image credit: Jefferson Hungerford, Yellowstone National Park (Public Domain)
“Are the new feature and the activity that started in 2003 hydrologically connected? Probably,” wrote Hungerford and Folz-Donahue. “One could run a line along the axis of the older active area and it would intersect the new feature. This line also follows the trend of faults that run from Norris Geyser Basin northward to Mammoth Hot Springs and beyond.”
The new hydrothermal feature also wasn’t the only exciting geological activity to take place last summer. Back in July 2024, there was a surprise hydrothermal explosion in Biscuit Basin, which sent debris ranging from the size of a grapefruit to that weighing hundreds of pounds flying up and into the distance.
Luckily, no one was hurt, but it just goes to show that you can never quite know what to expect at the oldest national park in the US.
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