Introduction to Geology

Thank you for your interest in the earth’s history.  Before you start the hike we would like to give you some basic information:

Like everything on this planet, the earth itself is affected by the continual change of time and by the law of CAUSE and EFFECT. The earth has a history just like all living creatures, including ourselves.  What you are seeing at this moment, changes continuously. These changes are the result of continuously reacting forces from the core of the Earth, gravity, the impact of weather and water, as well as all living organisms including mankind.  However, geological processes are slow; and therefore most of them are not recognizable by human beings during one lifetime. It takes thousands or even millions of years for a discernible result to show. During the last 4.5 billion years more than a dozen mountain chains the size of the Himalayas has existed on earth!

The earth itself has been in existence for about 4.5 billion years. Life has existed for about 3.2 billion years and the evolution of man began about 5 million years ago.

The Earth’s crust consists of several plates of different sizes and shapes which, during the past 4 billion years, have grown together, disappeared into the inner parts of the earth and separated. The plates of the Earth’s crust look like a football with black and white hexagons or plates.  Movements of the plates – like ice on water – cause earth quakes, and volcanoes which result in the eruption of lava.

The rocks of the Earth’s crust can be divided into three groups:

Every type of magmatic-volcanic rock is the result of the cooling and solidifying process of molten rock in the inner parts of the crust (like granite) or the eruption of lava like basalt.

All the types of sedimentary rock are the result of erosion of magmatic-volcanic and metamorphic rocks or the result from the precipitation of salt, gypsum or carbonate from mostly marine waters. Precipitation of sedimentary rocks implies that the oldest rocks are in the lower part and the youngest rocks are at the top of a sedimentary sequence.

All forms of metamorphic rocks evolve from magmatic-volcanic and/or sedimentary rocks during the impact of high pressure and temperatures at a great depth – mainly during mountain building processes.

Plate tectonics comprise the causes and movements of the Earth’s crust plates, the collision of plates and mountain building processes.

Nappes are units of undisturbed rock sequences that were sheared off their original basement and transported several hundred kilometres. Such units can be folded and sheared and therefore they themselves may, again, partly consist of smaller nappes.

Gravity tectonics is mass movements that are caused by gravity, erosion and water. The velocity of such mass movements may differ and its kind of transportation may be creeping, flowing, slipping or freely falling, like a rock fall.

Before you set out on the trail I’d like to give you the answers to the following questions:

Question 1: What is the reason for the terrace in the mountain slope where the Bartholomaeberg church was built? 

Answer: This terrace is the result of the forces of the Ill-glacier 13,000 years ago.

Question 2: Why does the mountain top of the “Tschaggunser Mittagsspitze” at the other side of the valley have such a rugged shape whereas the lower and middle parts are lovely green slopes?

Answer: The “Tschaggunser Mittagsspitze” consists of sedimentary rocks in the upper part and weak metamorphic rocks in the middle and lower parts. Moreover, during the ice age, the Montafon valley was filled with ice up to the contact zone from the weak to the rugged slopes. However, the glacier ice did not work on the ice-free peaks.

Question 3: The Weißplatte, Sulzfluh, Drei Türme and Drusenfluh mountains in the south consist of rugged, white rock, whereas the slopes in front of them are green and flat. What is the reason for the different shape?

Answer: Those rocks consist of white “Sulzfluh-Limestone” that was part of a continent that disappeared into the Earth’s core several 100 kilometres to the south. They are overlain by the older Silvretta gneisses (with the green slopes), part of the

African continental plate that was sheared off and thrust over the Sulzfluh Limestone from south to north.