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.