Global distribution of Fold mountains

lithosphere

• the lithosphere is broken up into rigid sections called plates.

• There are 7 major plates and several minor plates.

theory of continental drift

• according to the theory, plate tectonics move due to forceful convection currents in the earth’s mantle.

• resulting to fold mountains occurring.

Plates and Plate boundary

• plates meet at a plate boundary

• Fold mountains occur at convergent (destructive) plate boundaries.

• Because of the immense pressure of the collision causes the edge of plates to buckle upwards creating fold mountains.

three main fold mountain periods

• Caledonian Orogeny

• Armorican Orogeny

• Alpine Orogeny

Caledonian orogeny

• occurred 490 MYA

• E.g Bluestack and Wicklow mountains in Ireland.

• Took place when the American and Eurasian plates collided.

• resulting in SW-NE trend and is mainly located in the north western and Leinster regions in Ireland

• These are the oldest mountain period in Ireland

Armorican Orogeny

• took place in 250 MYA

• Causes a rise to the ridge and valley landscapes of Munster.

• Includes Macgillycuddy Reeks and the Galtees.

• Occurred when the African and Eurasian plates collided.

Alpine Orogeny

• took place 30 MYA and did not affect Ireland

• occurred when the Indian and African collided with the Eurasian plate

• Examples: Alps,Himalayas and Rocky mountains

• youngest fold mountains

• high peaks - denudation has not yet reduced their size