Periods of Folding

Another name for periods of folding

Orogeny

Periods of Folding

Geological intervals of large scale mountain building

How are periods of folding caused?

Caused by intense compressional forces at destructive plate boundaries

Layers of sedimentary rock folded into mountain ranges

How are periods of folding identified?

Identified using fossil evidence, radiometric dating and structural geology

3 Folding Periods

Caledonian - 400 MYA

Armorican - 250 MYA

Alpine - 35 MYA

Caledonian Folding Period

400 MYA

Laurentian Plate and Avalonian Plate

Wicklow Mountains, Appalachian Mountains

Type of Mountains at Caledonian

Rounded gently sloped mountains

→ Have been heavily eroded over time

Armorican Folding Period

250 MYA

African Plate and Eurasian Plate

Munster Ridge and Valley Province

Type of Mountains at Armorican

Ridges (Sandstone) and Valleys (Shale)

Clear anticline and syncline present

Alpine Folding Period

35 MYA

Indian and Eurasian Plates

The Alps and the Himalayas

Type of Mountains at Alpine

Tall, jagged peaks

Pyramidal

→ Didn’t have enough time to erode a lot and weather down