A fiord is a long, narrow arm of the sea, characterized by deep waters and steep, often towering, cliffs on either side. While commonly spelled “fjord,” the spelling “fiord” is also recognized, particularly in New Zealand English.
How Fiords Are Formed and What Defines Them
Fiords are shaped by the power of glaciers over thousands of years. During past ice ages, large glaciers flowed through river valleys, eroding the bedrock. This process involves ice segregation, where water freezes in cracks and expands, and abrasion, as the glacier drags rocks and sediment along its base, effectively acting like sandpaper.
The downward and outward movement of these glaciers created characteristic U-shaped valleys. Unlike rivers, glaciers can erode below sea level, resulting in very deep valleys, often hundreds or even over a thousand meters below the surface. For example, Norway’s Sognefjord plunges to depths of 1,308 meters, and Skelton Inlet in Antarctica is the deepest at 1,933 meters.
As the climate warmed and glaciers retreated, these valleys became inundated by seawater. The sea filled the depressions, forming the narrow, steep-sided inlets seen today. A common feature of fiords is a shallower “threshold” or sill at their mouth, formed by glacial deposits or where the glacier’s erosive power diminished as it reached the open sea.
Where Fiords Are Found Around the World
Fiords are found in coastal regions that experienced extensive glaciation. These areas are located in the higher latitudes of both the Northern and Southern Hemispheres, where ice sheets once covered the land. Their presence serves as a record of past glacial activity.
Norway is a well-known fiord region, with over 1,700 named fiords along its extensive coastline. The Sognefjord in Norway is the longest in the country, stretching 204 kilometers inland, and ranks as the world’s second-longest fiord. Other regions with numerous fiords include New Zealand, particularly its Fiordland National Park on the South Island, known for Milford Sound and Doubtful Sound.
Fiords are also found along the coast of Alaska, such as Glacier Bay and Misty Fjords. Canada’s British Columbia, Greenland, Iceland, and Chile’s Patagonia region also feature fiord landscapes. Greenland is home to Scoresby Sund, considered the largest fiord system globally, extending approximately 350 kilometers.