Geological History of Ireland

Early Continental Positions:

• 850 MYA: Ireland was split between two continents, Laurentia (North) and Avalonia (South), separated by the Iapetus Ocean.
• Laurentia: Part of today's North American plate.
• Avalonia: Part of today's Europe.

Closure of the Iapetus Ocean:

• 470 MYA: The Iapetus Ocean began to disappear due to the convergence/collision of Laurentia and Avalonia.
• Iapetus Suture: Marks the boundary of the plate collision, visible from Clogherhead to the Shannon Estuary.
• Marine Sedimentary Rocks: Found on Howth Head, Bray Head, and Sugarloaf Mountain.

Caledonian Orogeny:

• 490 - 390 MYA: Plate collisions led to mountain building.
• Result: Formation of the Bluestack and Wicklow Mountains.

Carboniferous Period:

• 400 MYA: Ireland moved closer to the equator and sank beneath a warm tropical sea.
• Sedimentary Rocks: Formation of sandstone and limestone.
• Example: The Burren in Co. Clare shows exposed limestone.

Armorican Orogeny:

• 250 MYA: Collision of the Eurasian and African plates.
• Result: Formation of mountains and valleys in Munster.