How did glaciers help form fjords in Norway and other coastal regions?

Fjords are formed through the powerful erosive action of glaciers on coastal landscapes. During periods of glaciation, massive glaciers descended from coastal mountains, carving deep, U-shaped valleys into the bedrock.123

These glaciers were exceptionally heavy and thick, allowing them to erode the valley floors far below sea level before the ice began to float in the ocean. Because glaciers are more viscous and have a larger cross-section than rivers, they effectively smoothed and straightened the valleys, creating the steep, vertical walls characteristic of fjords.142

When the climate warmed and these glaciers melted, the rising sea level inundated these deep, glacially carved troughs, creating the long, narrow arms of the sea known as fjords. This process is particularly evident along the western coast of Norway, where the scouring action of glaciers during the Quaternary Period transformed existing V-shaped river valleys into the deep, drowned landscapes seen today.132