This area consists of eclogites and tonalitic gneisses. The eclogites are crucial to understanding the Caledonian mountain-building event. They formed between 423 and 400 million years ago under extremely high pressure and temperature, corresponding to a depth in the Earth’s crust of 60–100 km. This shows that western Norway, during the mountain-building process, was pushed deep down beneath the massive stack of thrust sheets that had accumulated above it.
