The birth of the mountains

 

Mountains
 

The Swiss Alps are only the western par of an immense mountain system which runs across the European continent from Nice to Vienna. The deep valley of the Rhine and Rhône divide the Swiss Alps into two subsystem. The Northern Alps gradually flatten off, first into the Central Plateau, on the other side of which rise the Jura Mountains. The Southern Alps tower above the Po Basin of northern Italy, forming an almost insurmountable obstacle. The Northern Alps are cut through by the valley of the Reuss, which runs at right angles to the Rhine and Rhône, and, like them, has its source and headstreams in the St. Gothard Massif. St. Gothard is the of a real Alpine crossroads opening up to the four points of the compass. The Swiss Alps have about 50 peaks of over 13,000 ft, the greatest concentration of high mountains in the European system. Used to dealing in millions of years, the geologist looks upon the Alps with a certain degree of indulgence, for, geologically speaking, they are extremely young. They were formed during the Tertiary period, and the process was very simple. it was a logical step in the geological development of the earth Around its shores rose land masses whose rivers carried debris into the sea. This debris settled on the sea bed and, under the enormous pressure of the water, was gradually transformed into sedimentary rock: marl, sandstone, and limestone. But soon the earth’s crust, and with it the sedimentary rock layer, was folded by a tremendous thrust from the south. The folded rock rose higher and higher ,finally emerging above the water and forming islands. But the pressure continued, and the rock folded over towards the north, forming overlapping “pleats”, or overfolds. The Alps were now born, but they were to go through further startling changes. Erosion began to attack these extremely vulnerable masses of rock. The great rivers cut their way deep into the rocky layers and transported the sediment  into the sea.

This material covered a large area, the lightest elements drifting far beyond the coasts the soft Tertiary sandstone, or molasse, under which were layers of marl, sandstone, and conglomerate. But magma, the molten material beneath the earth’ crust, also played a part. It exerted immense pressure on the Alpine system, fracturing its limestone crust, and revealing the ancient crystalline substructures. Granite was the rock most frequently forced upwards from below. Sometimes it appear together with gneiss, the most common form of metamorphic rock. Tertiary limestone are the most common rock in the north. Heavily, eroded, and rich in fossiles, they sometimes enclose minerals, which give them surprising tints. They endow the surface of this region with its characteristic appearance. Thus the Alps were formed by horizontal continental thrusts and vertical magmatic outbreaks.  Erosive activity started as soon as the land masses emerged from the sea and has never ceased. Erosion is a sculptor of planetary stature, never ceasing to work on the granite to form all kinds of bizarre shapes, and on the limestone to carve out steep cliffs, or jagged ridges; transitional shapes of all kinds are to found where harder and softer rocks occur in the same area. Erosion has many agencies, apart from the simple action of wind and water. Rain seeping into small cracks and then freezing, for example, can split the rock. And thermal fluctuations leading to the expansion and contraction of rock can also ultimately have an erosive effect. The slow death of the mountains is often dramatically emphasized by violent landslides. The rubble is away by rivers and accumulation on the sea bed. And perhaps in many million year’s time a new cycle will begin.

 

 

 

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