Natural Hazards – Fold Mountains

     Fold mountains occur near convergent or compressional plate boundaries. Examples of fold mountains include the Alps, Rockies, Andes and Himalayas.

Formation and characteristics

The formation of fold mountains

                                     The formation of fold mountains

 

The formation of fold mountains

  1. Where an area of sea separates two plates, sediments settle on the sea floor in depressions called geosynclines. These sediments gradually become compressed into sedimentary rock.
  2. When the two plates move towards each other again, the layers of sedimentary rock on the sea floor become crumpled and folded.
  3. Eventually the sedimentary rock appears above sea level as a range of fold mountains.

      Where the rocks are folded upwards, they are called anticlines. Where the rocks are folded downwards, they are called synclines. Severely folded and faulted rocks are called nappes.

Characteristics of the Alps

Matterhorn, Zermatt, Switzerland

    Matterhorn, Zermatt, Switzerland

Characteristics of the Alps

  • High mountain ranges, eg Mont Blanc, which is 4,810 m above sea level.
  • Glaciated valleys, eg the Rhone Valley.
  • Pyramidal peaks, eg the Matterhorn.
  • Ribbon lakes, eg Lake Como.
  • Fast-flowing rivers.
  • Contrasting microclimates on north facing (ubac) and south facing (adret) slopes.
  • Geologically young (30-40 million years old).

 

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