Sognefjord, on the western coast of Norway, is the longest and deepest fjord in the world.

It extends inland a distance of 200km (125 mi) from the Solund Islands on the edge of the North Sea. Its sheer cliffs extend almost vertically, to a height of 900m (3,000ft) in places. At one point, near the town of Vadheim almost a third of the way in from the sea, Sognefjord descends to a depth of 1,234m (4,078ft).

From the summit of its cliffs to the bed of its waters, Sognefjord is one and one third times as deep as the Grand Canyon.

Steep cliffs and snowcapped mountains rise from the water's edge; picturesque villages and farms nestle in every habitable area of land. Waterfalls cascade through forested slopes or over bare rock into the waveless waters of the fjord.

The dramatic scenery of Sognefjord can best be seen from the ferries that daily ply its waters. Beside the mouth of the fjord, bare rounded hills rise steeply from the sea. Covered only by the thinnest soil with limited fertility, these low hills can support only a small population. Farther inland, the sheer cliffs rise so steeply from beneath the water that large ferries can pass to within an arm's reach of them without running aground.

At the town of Balestrand on the north bank, the fjord of Fjaerlands branches off for 25km (15mi). Its waters are fed by the Jostedal Glacier, Europe's largest glacier and a remnant of the glaciers that created Sognefjord. After the ice age ended, the Jostedal Glacier is thought to have disappeared altogether. However, it returned during the "little ice age," between the 15th and 19th centuries, and attained an estimated thickness of 300m (1,000ft).

After bending northward between Balestrand and the ancient Viking town of Vik on the south bank, Sognefjord begins to branch into smaller, tributary fjords where the climate is warmer and wetter. These are rarely deeper than 300m (1,000ft), whereas the water in the main trunk of Sognefjord is seldom shallower than 800m (2,625ft).

At the point where Sogndalfjord branches off to the north and Aurlandsfjord to the south, an increasing amount of land is used for farming and fruit-growing purposes. The town of Liekanger alone has more than 60,000 fruit trees, mainly peaches, apricots and walnuts. In these branching fjords, and at the head of Sognefjord, the land has risen around 100m (330ft) since the end of the ice age. This elevation was caused by the inrushing sea, which brought vast amounts of sand and gravel to form delta fans and narrow terraces at the foot of the retreating glaciers.

Behind the town of Kaupanger on the north bank, Norway's highest continuous slope rises more than 915m (3,000ft). After this point, Sognefjord terminates in three branches: Lærdalfjord, opposite Kaupanger to the south; Årdalfjord to the east; and Lusterfjord to the north.

Lusterfjord, Sognefjord's longest branch, and one of its broad¬est, extends for 48km (30mi). At its tip is Sognesfell, a pass which leads to the Jotunheim, which means "home of the giants" in Norwegian. These mountains, which are geologically related to the ancient rocks of Scotland, contain the highest peak in Scandinavia - Glittertinden, which rises to 2,472m (8,110ft).

How Sognefjord was Formed

For much of the Earth's lifespan of approximately 4,600 million years, its climate has been hot and dry, its continents devoid of ice. However, geologists have detected seven ice eras, each lasting around 50 million years, in which cooler, wetter climates have predominated. The most recent of these ice eras began around 65 million years ago. It has been marked by six ice epochs when global temperatures were especially cold. Each epoch spans roughly 2.5 million years.

Within the epochs are periods, known as ice ages, of exceptional cold and these are coupled with extensive glaciation. The last ice age started around 125,000 years ago, peaked some 50,000 years ago and ended in about 8,000 BC. For most of this ice age, temperatures at the poles were far colder than they are today. Huge ice sheets covered much of northern Europe and North America. Flora and fauna from these regions retreated southward. The habitats on the threshold of the ice sheets were tundra and bleak scrubland, populated only by mammoths, hairy mastodons, woolly rhinoceroses and musk oxen.

In each successive ice age, Scandinavia was submerged under a gigantic ice sheet for thousands of years at a time. At Sognefjord, an ancient river system was covered by glaciers that moved down from the surrounding mountains. As glaciers appeared and reappeared, they gouged out more and more rock and earth from the side valleys as well as from the main river valley itself.

The glacier that created Sognefjord's present shape during the last ice age was thickest at the head of the fjord, around 210km (131mi) from the open sea; estimates put its thickness here at 3,000m (9,840ft). It as was at its thinnest - between 100m (330ft) and 300m (1,000ft) thick - About 50km (31mi) from the sea

About 10,000 years ago, the glacier receded forming a classic glaciated valley: U-shaped, flat-bottomed, its rock walls scratched with lines, and less deep at the seaward end where the glacier lost its power of erosion. The North Sea's waters then flooded in.