Case Study: Ireland’s Incredible Journey
The land we now call Ireland did not always lie in the northern hemisphere and deep within the Eurasian Plate as it does today. Moving crustal plates carried Ireland across much of the world over hundreds of millions of years. The story of this journey is outlined below.
a u NW Ireland SW Ireland q
l About 850 mya (mya = million years ago). The place we now call northwest Ireland lay at the edge of the North American Plate and was situated just south of the Equator. The rest of Ireland was part of another landmass much further south. Plate movements caused the two parts of Ireland to drift towards each other (Figure 13a).
(a) 850 million years ago rotauqE
l About 400 mya, the two parts of Ireland collided and were welded together. Ireland was then about 20 degrees south of the Equator. The collision of plates that welded Ireland together caused faulting, folding and volcanic activity. The Caledonian mountains of Donegal and other parts of northwest Ireland were folded around this time.
(b) 350 million years ago
l By 380 mya, Ireland had drifted north towards the Equator. It had a hot desert climate and the sandstone of Munster was laid down.
l By 350 mya, Ireland lay just south of the Equator (Figure 13b) and beneath a warm tropical sea that teemed with fish and other sea creatures. The remains of these creatures formed the limestone that is now Ireland’s most common rock type.
E q (c) Today 10
13 How Ireland’s position in the world has changed
l About 250 mya, Ireland had moved to about 20 degrees north of the Equator and lay deep within a huge landmass. A collision of crustal plates caused the mountains of Munster to be folded.
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