Yellowstone National Park is home to three different types of thermal activity, acid-sulfate springs, alkaline-chloride springs, and calcium-carbonate springs. Only a few places in the park are home to these calcium-carbonate, or travertine, springs, most notably at Mammoth Hot Springs.
These calcium-carbonate springs exist as thermal waters pass through and dissolve rocks that are carbonate-rich, being deposited tens to hundreds of millions of years ago when Yellowstone was still covered by a shallow sea. But a different calcium carbonate area in the park, Silver Gate, exists for a rather different reason.
If you’ve visited Mammoth Hot Springs there’s a good chance you’ve seen Silver Gate, informally known as “the Hoodoos”. The jumble of closely spaced white/gray boulders is only a few minutes outside Mammoth. Despite now having no thermal activity, Silver Gate was once made up of travertine hot springs that likely resembled the modern terraces of Mammoth Hot Springs.
So why does it look like the jumble that it looks like today? A view from the top makes the answer a whole lot more clear. Silver Gate is the remnants of a landslide, occurring at some point in the past 15,000 years after the most recent ice age.
