How were the Alps formed? A short guide to the Alps’ geology

It is difficult to visit the Alps without becoming curious as to how the majestic mountains were formed. The Alps rose up due to the collision of the African and European tectonic plates, but the present-day landscape with iconic jagged mountains such as the Matterhorn are the result of millions of years of glacial activity and erosion. Here is a short guide to the geology of the Alps from the big bang to the present day:

15bn years ago: The Big Bang

4.5bn years ago: The early earth was formed

250 million years ago: Pangea

  • The earth is very hot and dry with a lot of volcanic activity.
  • The world’s land mass is comprised of one supercontinent called Pangea.
  • At this stage the rocks which will later form Mont Blanc and the Matterhorn are lying dormant under sandy coastal dunes.

240 million years ago: First Dinosaurs begin to walk on earth

220 million years ago: Pangea splits into Laurasia and Gondwanaland

  • Convection currents in the earths mantle cause the continental crust of Pangea to split forming 2 continents – Laurasia and Gondwanaland – with an ocean called the Tethys sea between them.
  • Tectonic activity cause Laurasia and Gondwanaland to move further and further apart and the Tethys sea grows by 2cm per year.
  • The rocks that will form the future Mont Blanc are part of the Laurasian continent and the rocks that will form the Matterhorn are part of the Gondwanaland continent. The geology of the Alps is becoming more and more recognizable (at least for modern hikers).

160-120 million years ago: The Tethys sea continues to expand, and the Atlantic Ocean begins to form

130 million years ago: Continents continue to split apart

Convectional currents in the earth’s mantle cause the continents to begin to split apart. Most notably modern-day India detaches from the African plate and begins its long migration northwards. It will later collide with Asia and this collision will form the Himalaya.

60 million years ago: Mass extinction

  • A 10km wide asteroid hits the earth with a force that is 1 million times more powerful than a nuclear bomb. This leads to the extinction of all dinosaurs and ammonites.
  • At this stage the Alps is still under water, which is the reason why so much of the rock found in the Alps is formed of sedimentary limestone.

35 – 20 million years ago: Continents collide, and the Alps begin to form

  • The North part of the African plate collides with the European plate and is thrust over the European plate. This is the start of the formation of the Alps which grows by 1000m per million years.
  • The Matterhorn is an interesting example of this collision:
    • The base of the Matterhorn contains rocks which were formed under the Tethys sea. As the African plate moved into the Eurasian plate the denser oceanic crust was subducted under the lighter, continental crust.
    • The centre of the Matterhorn contains rocks from the Eurasian plate.
    • The top of the Matterhorn comprises of rocks from the African plate which was thrust up on top of the Eurasian plate when it collided together.

5 million years ago: Early humans are evolving in Africa

  • Favourable climatic conditions in the great rift valley of Africa leads to the evolution of our early ancestors.
  • The earliest footprints of our ancestors can be found preserved in volcanic ash in Tanzania and show an adult and child walking upright on two legs side by side – they are believed to date back to 3.5 million years ago.
  • The Arabian plate joins the Eurasian plate and early hominids can migrate to Asia and Europe.

2.4 million – 1.6 million years ago: The Quaternary Period

  • The Quaternary period is a geological time period characterised by progressive cooling.
  • There were cycles of 100,000 year glacials (cooler periods in which glaciers advance), interspersed with 15-20,000 year inter-glacials (warmer periods in which glaciers retreat).

100,000 years – 40,000 years ago: The last great ice age

  • The Alps, the Swiss Plateau and the Jura mountains were completely covered in Ice.
  • The Rhone Glacier reached all the way to where the modern-day city of Lyon stands.
  • 100,000 years ago – the first homo sapiens evolved.
  • 40,000 years ago – homo sapiens displaced Neanderthals at the end of the last great ice age.

18,000 years ago: Climate begins to warm up again

  • The sea level which was 120 metres lower than today, begins to rise.
  • The Rhone Glacier retreats to Geneva but is still immense; reaching 700m above the present-day cities of Lausanne and Evian.

10,000 years ago – Present day: Holocene Period

  • At lower altitudes the warming climate means allows pine and birch forests to give way to hazel, oak, ash and linden trees.
  • The absence of ice on mountain sides causes huge amounts of rock fall, forming the iconic steep sided faces of the Alps that we see today.

If you would like to find out more about the geology of the Alps, an excellent resource is the book ‘The Alps and our Planet, The African Matterhorn: A Geological Story’ by Michel Marthaler.

If you are interested in seeing the magnificent geology of the Alps firsthand, you may want to consider a trekking tour of the Alps.

Jennifer Stretton
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