New rising – tertiary (65–2.5 million years)

About 65 million years ago (in the late-Mesozoic period – early tertiary) there was probably nothing left of the high Caledonian mountain range. It had been eroded down, so the landscape in most of Norway was low-lying and flat, characterised by rolling plains with wide valleys and rounded hills.

During the early tertiary the area became tectonically active. The continents pulled apart, and a sea was created between Greenland and Scandinavia about 55 million years ago.

Rising of the land

The weight of an enormous ice cover had pushed the Scandinavian crust downwards, and when the ice melted and retreated, the great rising of Norway took place (throughout the tertiary 65–2.5 million years ago), with considerable displacement along the fault system parallel to the coastline.

The rising was uneven, and we got a high, mountainous area parallel to the west coast that gradually sloped off and became softer towards the low-lying areas in the East. The sloping of the land and the accentuated topography resulted in a strong increase in erosion by water, and the old drainage system was rejuvenated. The result was steep and deep river valleys. When the great inland ice appeared about 2.5 million years ago, the ice excavated deep and wide valleys.

Deep sediments

The fjords and the valleys extending up from the end of the fjord, were thus originally old river valleys from before the ice ages (usually V-shaped valleys) that the ice excavated and re-shaped into U-shaped valleys.

Today the fjords are generally narrow, steep and deep, usually with large basins and thresholds. The fjord basins contain sediment up to 300 metres thick, with a very slight slope of less than one metre per kilometre.

Erosion

Rising of the land after the ice has retreated leads to slow but visible changes along the coast of the fjords and causes development of delta, mainly be the end of the fjord (e.g. in Geiranger). In contrast to this there is the dramatic effect of erosion in deep crevices and gorges, rockslide and snow cover that create more obvious changes to the landscape.

These geological processes are partially controlled by precipitation (snow and rain) in the Atlantic climate in the west of Norway, and they make a more striking effort to shape the landscape. Still – most of the erosion that has taken place since the ice age has had a very local effect and compared to the ice ages rather small effect, so the landscape and fjords created by the glaciers are looking unusually good for their age.