The best example of a landform resulting from sea-floor spreading is the Mid- Atlantic Ridge. This submerged mountain chain stretches over 40,000 km from the North Pole to the South Pole. The crust is moving apart at a rate of about five cm per year. This works out at
about 25 km per million years. This may seem slow to us, but the Atlantic Ocean was created in 200 million years.
Sea-floor spreading in Iceland
Iceland has formed where the Mid-Atlantic Ridge appears above the sea. Iceland is getting wider due to the process of sea-floor spreading. One side of the country is on the North American plate, the other on the Eurasian plate.
Iceland has over 200 active and dormant volcanoes. There are also many long cracks, or fissures, which form as the crust is split. Magma erupts through these. Submarine eruptions are common in the south-west. Earthquakes are frequent but rarely dangerous.
The Eyjafjallajokull volcano erupted throughout 2010, disrupting transatlantic and European flights.
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NORTH
AMERICAN PLATE
EURASIAN PLATE
Krafla
Geotherma l
Reykjavik Katla Eyjafjallajokull Atlantic Ocean = active volcano Fig. 20 Map of Iceland