Fjord: glacially carved coastal inlet with steep sides

Formation and characteristics

Fjords form where moving ice—most commonly glaciers—erode bedrock, carving deep, U-shaped valleys. When the ice melts and sea level rises or land subsides, seawater fills the valley, producing an inlet that is typically much deeper than the adjacent open sea and has steep walls. Many fjords have a shallow threshold or sill at their mouth, created by reduced erosion near the ocean, which can affect water circulation and create distinct layers of salt and fresh water.

Where fjords occur

Fjords are most abundant in regions that experienced extensive Pleistocene glaciation. Classic and well-known locations include Norway, which has some of the most famous fjords, as well as parts of Sweden, Denmark, Canada, Germany, and New Zealand. They are also common along the coasts of Chile, Scotland, Greenland, Iceland, Alaska and other formerly glaciated coastlines.

Examples and notable fjords

• Sognefjord and Geirangerfjord (Norway) — often cited for dramatic scenery.
• Milford Sound (New Zealand) — a steep-walled inlet formed by glacial action.
• British Columbia and Newfoundland in Canada — many complex fjord systems.

Human uses and ecological importance

Fjords frequently serve as sheltered harbors and have supported settlements, fisheries and transport routes for centuries. Their stratified waters and varied depths create rich marine habitats and unique ecosystems. In modern times they are important for tourism, scientific research into past climates and glacial processes, and as indicators of landscape change in response to ice retreat and sea-level shifts.

Distinctions and notable facts

Fjords differ from drowned river valleys (rias) in their U-shaped cross section and glacial origin. Many possess a shallow entrance sill that influences tidal flow and marine life, giving fjords characteristic circulation patterns. Though the basic process is straightforward—ice erosion followed by inundation—the resulting landforms are diverse in scale and shape, and they remain prominent features of many coastal regions shaped by past ice ages.