Geoscientists have been arguing for over a hundred years how the Norwegian mountains came to be. I find this fascinating since the mountains dictate where we live, how we live and how we move around, and are the basis for natural resources.
Photo: Geir A. Granviken
Both sides of the argument stem from the same story. We travel back in time, 420 million years, when Norway was part of a large mountain chain formed by a collision with the landmasses of Greenland. Plate tectonics do that sometimes; they make landmasses collide and then later split. Norway and Greenland also drifted slowly apart and created the Atlantic Ocean in between. The question is what happened onshore Norway after the break-up and until today.
Here is where geoscientists have split opinions. Some claim that the large mountains were completely leveled out before later tectonic fault events created the topographically high west coast. Others believe that this 420 million year old mountain chain never flattened, it only diminished through erosion. For both theories, isostatic uplift is a key element for our understanding.
Imagine a cube of ice floating in a glass of water; only a small part of the cube stays over the surface, the rest below. If the cube should melt, the portions of ice floating above and below the water surface will stay the same. This is isostatic uplift. We can think of the Earth’s crust the same way as it floats on the warm mantle below; high mountains have proportionally deep roots. When mountains erode, they get lighter and rise through isostatic uplift. Therefore, for mountains to become smaller, the erosion needs to exceed the isostatic uplift. We know the Norwegian mountains did become lower through this process. But did they slowly erode to what we see today, or did they completely erode away only to rise again?
Over the next years, I will use different methods to study the erosion and isostatic uplift of the Norwegian mountains. My research aims to fit more pieces to the puzzle to understand the story of the mountains that influence our lives so much.
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Åse Hestnes
Latest posts by Åse Hestnes (see all)
- The rise of the Norwegian mountains - April 29, 2019