Strokkur geyser Iceland sits right on top of the Mid Atlantic Ridge, a 10,000-mile long crack in the ocean floor caused by the separation of the North American and Eurasian tectonic plates. Along the mid-Atlantic ridge, the tectonic plates are moving away from each other at the rate of around 1.8cm per year. As they do this, they release pressure and expose lava between them. The lava bubbles to the surface and cools, forming new land. This is exactly how the island of Iceland formed some 20 million years ago.
Volcanic forces are still very active on Iceland.
On average, Iceland experiences a major volcanic event once every 5 years, the most active volcano being the picturesque Mount Hekla. Active vulcanism can also be seen in the abundant geo-thermal activity on the island. Iceland was created by vulvanism but it is glacial activity which shapes the island. Iceland was covered by ice, and this glacial activity was responsible for Iceland's fjords and valleys. The largest glacier, Vatnajokull, is 3,200 feet thick and 3,200 square miles in area.