What are the types of disk rims

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The Alps are a mountain of folds. Like many other mountains, they were created when two plates collided, i.e. at a destructive plate boundary.

After the continent of Eurafrica broke up into the African and European plates about 160 million years ago, the two plates initially diverged from each other. Sea water penetrated between the plates and formed the so-called Pennine Ocean. During the Triassic and Jurassic periods, layers of mud were deposited in this area, which turned into limestone. In the middle of the ocean, new oceanic crust was constantly being formed on a mid-ocean ridge, pushing the plates further apart.

The movement was reversed in the Cretaceous about 130 million years ago. The African plate was now moving towards the European one. The oceanic crust of the Pennine Ocean disappeared in a deep sea trench off Africa (subduction). At the same time, the many hundreds of meters thick sedimentary rock banks from the Triassic and Jurassic were cut up and folded.

The continents collided about 50 million years ago. The continental crust was compressed and increased in thickness. The crust, which is now about twice as dense, underwent a process of isostatic equalization and began to rise about 30 million years ago. The mountain formation had begun.

So the uplifting of the Alps has two different causes: 1. Bulging due to colliding plates; 2. Isostatic compensation movement.

  • More than 200 million years ago, the ancient continent of Pangea was surrounded by the ancient ocean.
  • Currents in the lower part of the earth's mantle tug at the continental crust, the supercontinent breaks up.