The fold mountains of the Cape are among the most prominent features of folding. Image via AfricanSky.

The fold mountains of the Cape are among the most prominent features of folding. Image via AfricanSky.

Land-forms resulting from folding

Several landforms are formed during the folding process including:

  1. Anticlines
  2. Nappe fold
  3. Overthrust
  4. Overfold
  5. Recumbent
  6. Fold mountains

1. Anticline

A diagram showing a syncline and an anticline. Image via Pinstopin

A diagram showing a syncline and an anticline. Image via Pinstopin

  • An anticline is a fold that is arched upward to form a ridge or mountain.
  • It can be defined simply as a highland area/ridge that is formed due to compressional forces.
  • It is convex shaped.
  • They are formed out of rock units that are folded in the same pattern.
  • They are a result of a simple fold.
  • Each side of a fold is called a limb.
  • The topmost point is called a crest/axial line.
  • The axial line acts as a line of symmetry between the two limbs.
  • The shape of an anticline is like an inverted letter “U
Real life anticline in Lebanon. Image via MediaWiki.

Real life anticline in Lebanon. Image via MediaWiki.

2. Syncline

  • A syncline is a fold that arches downwards to form a fold.
  • Are usually made up of rocks units that are folded in the same pattern.
  • Are concave shaped.
  • Usually occur in conjunction with anticlines as shown on the diagram below.
  • An anticline is shaped like the letter “U
A diagram showing the formation of anticlines and synclines.

A diagram showing the formation of anticlines and synclines. Image by Radford University.

3 Over thrust

  • If compression forces continue to act on the rock layers a simple fold (from which anticlines and synclines are formed) progresses into an asymmetrical fold, then into an over fold and
  • Finally into an over thrust fold.
  • An over thrust is actually a fault.
  • Older rock is exposed as it covers younger rocks.

4. Over-fold

  • Occurs when one fold is pushed over the adjoining limb due to increasing compressional forces.
  • They are also known as overturned folds.
An overfold. Image by StudyBlue.

An overfold. Image by StudyBlue.

5. Recumbent

  • Occurs when the limbs are nearly parallel to each other and the axis of the fold is horizontal.
  • The axis of the fold is horizontal.
A recumbent fold. Image by StudyBlue.

A recumbent fold. Image by StudyBlue.

6. Fold Mountains.

  • Are formed as a result of folding in the upper layers of the earth’s crust
  • This is as a direct result of compression forces when tectonic plates move against each other from opposite directions i.e. forces acting against one another
  • Acting on rocks that are not brittle but are flexible.
  • These mountains are formed by orogenic forces.
  • When the two plates collide the crumple and fold in a shape not unlike that of a table cloth.
  • A lot of folded mountains are formed in narrow elongated seas called geosynclines.
  • Fold mountains typically have a short width but have a longer length which may span several thousand kilometers.
  • Examples of fold mountains include the Jura mountains, Himalayas, the Cape Range Mountains and the  Mt Everest in Nepal.
Two contintal plates moving against each other to form fold mountains. Image by ParkfieldPrimary.

Two contintal plates moving against each other to form fold mountains. Image by ParkfieldPrimary.

continental_oceanic_fold_mountains

Two continental plates moving towards each other resulting in a trench and fold mountains. Image from Localwiki

Here a diagram showing an oceanic plate and a continental plate moving towards one another leading to the formation of fold mountains.

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