Folding & Faulting

Folding

When Earth’s crust bends, folds occur

Folding occurs under compression when forces act towards each other, such as when plates collide. 

Definitions

Compression

·Is a process of forcing something into smaller compass, reducing it in volume by pressing it together

Tension

·Is a pulling force, tending to stretch, to cause an extension of a body or to restore the shape of an extended elastic object 

A fold is a bend in the rock strata.

Folding: Is a type of earth movement resulting from the horizontal compression of rock layers by internal forces of the earth along plate boundaries. 

Parts of a fold :

layers of rocks of continental crust bent in upfolds called anticlines & downfolds called synclines.

2 sides of a fold are called the limbs.

Generally, anticlines form fold mountains  & synclines form valleys

There are 2 main fold mountains systems in the world:

Old and young fold mountains, based on their geological age.

A) The old Caledonian fold mountains (formed 400 million years ago)

B) The Circum-Pacific Region surrounding the pacific    ocean (formed within the last 100 million years)