A Modern Hot Spring Setting

Yellowstone National Park in Wyoming, USA is famous throughout the world for its present day hot springs and geysers, with the ‘Old Faithful’ geyser being the most famous. The park covers more than 2 million acres and sits about 8,000 feet above sea level. It has the largest concentration of active geysers in the world today, with more than 10,000 geothermal features, such as geysers, hot springs and fumaroles. There are currently around 250 active geysers at Yellowstone, each of them named and displaying different heights and frequency of eruption.

Although the area is still classed as volcanically active, for now, there are no actively erupting volcanoes at Yellowstone – the last eruption was around 70,000 years ago. Despite this, the magma chambers beneath the volcanoes are still very hot. These lie about 5km below the surface and heat fluids which circulate through the rocks above. This in turn heats the groundwater. The temperature of the waters can reach around 250oC which is hot enough to dissolve quartz and other minerals. When this happens, the water becomes very rich in silica. When the water cools, the silica precipitates – or hardens – and forms sinter.

Today at Yellowstone, sinter deposits are being formed around the edges of the hot springs and geysers, just as it did at Rhynie around 400 to 412 million years ago. By looking at the Yellowstone hot spring system, we can picture how Rhynie may have looked when its own geysers were erupting.

In this photo, we can see white sinter being formed around the edge of Abyss hot spring pool at West Thumb Basin, Yellowstone.
Photo © Dr Lyall Anderson, National Museums of Scotland.

Click here to find out more about geothermal features.