Why is Norway’s coastline so deeply indented?

Norway’s coastline is deeply indented primarily due to the powerful erosive forces of glaciation during the Ice Age of the Quaternary Period.1

Before the glaciers arrived, rivers flowing westward followed fracture lines in the Earth's crust, carving out deep gorges and canyons. During repeated glacial periods, these V-shaped valleys were scoured and widened by massive glaciers, transforming them into the characteristic U-shaped, steep-walled fjords that define the western coast today. As the ice retreated, these deep troughs were partially drowned by the ocean, creating the country's signature jagged, indented shoreline.12

While some researchers suggest that tectonic activity may have also played a role in shaping the initial valleys, the dramatic, deep-cut appearance of the coast is widely attributed to the intense scouring action of these ancient glaciers.12