Lihesten: From Deep Valleys to Majestic Landmark

Around 400 million years ago, Lihesten lay several kilometres further east, at the bottom of a deep valley, high up in the Caledonian mountain range. This ancient mountain range was formed as a result of the collision between the ancient American continent and the European continent. The Caledonian Mountains were at least as high as today’s Himalayas, and the valley—what we might call Lihest Valley—was likely situated 7,000 to 8,000 metres above sea level.

The mountains surrounding the valley were unstable, and rockslides from the steep slopes were common—something we can still recognise in today’s mountain landscapes, especially along the Norwegian west coast. Over time, all this landslide debris gradually accumulated at the valley floor. At the bottom of the valley, there were most likely rivers and lakes, where rushing water shaped the rocks, smoothing them into rounded stones. These stones were eventually buried under new rockfalls, going through the same grinding process once again.

A Stratigraphic Thickness of Over 14 Kilometres

As mentioned, the Caledonian mountain range was extraordinarily high, and over time, processes deep within the Earth’s mantle caused the range to collapse—most likely because the mountains became too tall and heavy. This is a geological process we can also observe in today’s Himalayas, where the Tibetan Plateau is slowly sinking by a few millimetres each year.

At that time, Hyllestad lay deep within the Earth’s crust, and the mineral composition of what we now call Hyllestad Schist indicates that it formed at a crustal depth of 60 to 80 kilometres. Although the word collapse might suggest something sudden, this was a process that unfolded over millions of years.

For Lihest Valley, this collapse meant that the entire valley gradually slid downwards along a major fault line known as the Nordfjord-Sogn Detachment Zone. This fault likely formed on the eastern side of the valley floor. Although the valley sank at a rate of only a few millimetres to centimetres per year, the rockslides from the surrounding mountains continued, along with the rivers and lakes, which descended gradually with the valley itself.

Eventually, Lihest Valley ended up where Hyllestad is today, and the Lihesten Conglomerate is now estimated to have a stratigraphic thickness of over 14 kilometres.

Today, Lihesten is no longer a valley, but a majestic mountain peak. If you look closely, you can spot a line sloping westwards beneath the conglomerate, separating the vegetated area from the bare rock. This line is part of the major fault zone along which Lihest Valley once slid.

There are also clear traces of the Nordfjord-Sogn Detachment Zone visible beneath Stigfjellet on Losna and beneath Kvamshesten, also known as Storehesten.

A Little Piece of America

The Lihesten Conglomerate actually rests on top of a remnant of the ancient American continent, so if you’re looking for a shortcut to America, this is about as close as you can get!

The Lihesten Conglomerate, originally deposited in a valley thousands of metres above sea level, now lies just a few hundred metres away from rocks formed 60 to 80 kilometres deep in the Earth’s crust.

The reason these very different rock units sit so closely together today is thanks to the Nordfjord-Sogn Detachment Zone, located directly beneath Lihesten.

Text by FjordKysten Regional and Geopark.