The Norwegian Fjords are steep, ice-carved valleys that stretch from the land
out into the sea. Fjords are created not solely by glacier erosion, but
also by the high-pressure melt water that flows beneath the ice. Fjord
valleys can be carved hundreds to thousands of meters below sea level. The
Hardangerfjorden shown in this image is about 179 km long, and reaches its
maximum depth of more than 800 m about 100 km inland.
In the above image, based on elevation data collected by the
Shuttle Radar Topography Mission (SRTM), beige and yellow represent low elevations,
while red, brown and white represent progressively higher elevations. Shades of blue represent
water. The Hardangerfjord is left of center, and extends off the top of the
image. Sorfjorden is towards the right edge of the image.
The location of a fjord may be due to pre-glacial valleys, bedrock
characteristics, or fractures in the Earth's crust. Fjords typically have U-shaped cross-sectional profiles, with the valley floor being flat or only
slightly rounded. The fjord's longitudinal profile usually consists of a
series of basins separated by rock barriers or moraine sills (glacial
debris). Fjord entrances are usually quite shallow with shoals and small
islands. Usually the deep basins are situated some distance inland from the
mouth of the fjord. The shallow mouths are places where the glaciers that
once filled the valley either began to float, or else had room to spread
out. Inland, the glaciers were more confined, and so they carved more deeply
into the Earth.
About 10,000 years ago, at the end of the last major glaciation, the
Scandinavian land mass began slowly rising up as warmer temperatures freed
it from the enormous weight of glacial ice, a process called glacial
rebound. However, the land's increased buoyancy did not keep pace with the
rising sea level, and the lower parts of formerly glaciated valleys became
flooded. The glacial rebound of the Scandinavian land mass is still
occurring.
Image courtesy German Remote Sensing Data Center, based on data from
the SRTM.