PLATE TECTONICS
Souvenirs of Ireland’s tectonic travels
Describe briefly when and in what circumstances each of the items shown in the photographs was formed.
l Between 200 and 100 mya, Ireland continued to drift further northwards. Sea sediments that were rich in organic matter began to form the gas deposits that are now found off Counties Cork and Mayo.
l About 65 mya, the American and Eurasian plates began to split apart and move away from each other. The separating plates allowed sea water to rush in and form what we now know as the Atlantic Ocean. Separating plates also allowed magma to emerge through fissures in the earth’s crust and to form volcanic ridges and plateaux made of basalt. The Antrim Plateau and the Giant’s Causeway were formed at this time (see page 19).
Sandstone
Limestone
The Galtee Mountains in Tipperary
The Giant’s Causeway with part of the Antrim Plateau in the background
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