Fjords are steep-walled, U-shaped, glacial-carved coastal valleys. Especially common along the rocky coasts of Norway, Iceland, Greenland, Canada, Alaska and Russia, they are also found in New Zealand and southernmost South America. Eroded by mountain glaciers as they flowed toward the sea, the cliff-lined channels now admit ocean waters; since sea levels were much lower during the Pleistocene, the floor of many fjords is hundreds if not thousands of feet below the water surface (and generally deepest inland). Furthermore, since the glacial tongues left terminal moraines beyond the rocky headlands, those underwater ridges now produce upwelling and strong currents near the mouth of many fjords.
Among the more famous fjords is Sognefjord, in southwestern Norway. More than 125 miles long and over 4200 feet deep, this scenic, branching channel is the longest fjord in Europe and is second only to Greenland's Scoresby Sund in depth; its majestic cliffs rise 3300 feet above the water line. Long a natural waterway for explorers, settlers, fishermen and traders, Sognefjord is now traversed by pleasure boats and cruise ships.
Of course, fjords also offer prime nesting habitat for seabirds such as puffins, murres and kittiwakes and hunting grounds for whales, dolphins and seals; cold water reefs have been found in some fjords (especially those of Norway and New Zealand) and most harbor rich fisheries for salmon and other marine species. How global warming is effecting the ecology of these spectacular waterways is the subject of intense study.
